natraj jsp

8/17/2019 Natraj Jsp

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“JSP” Web application is collection of web resource program generating web page.

Based on content that is generated there are two types of web resource prog.

a) Static web resource prog

Generates the static web pages.

b) Dynamic web resource prog.

Generate the dynamic web pages.

Based on the place of execution there are two types of web resource prog

a) Client side web resource prog (eg:- html, java script)

These programs go to browser window for execution.b) Server side web resource prog (eg: servlet , jsp prog)

These program execute by residing in the server

Note: - Decide whether web resource program is client side or server side based

on the place where it executes, not based on the place where it resides.

Client side web Technology:-

(useful to develop client side web resource program/components)


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Html

javaScript

Ajax

Jquery Angular JS

And etc……..

Server side web Technologies:-

(Useful to develop server side web resource prog/components)

Servlet (SunMicro system)

Jsp (SunMicro system)

SSJS(Server side java script) (from Netscape)

PHP (from Apache)

Asp

Aps.net (from Microsoft)

Aps.net MVC

Q:-Why SunMicro system has given JSP even they already got aserver side technology called servlet ?

o In the initial day of servlet the Microsoft ASP programmer have not liked

servlet even though it is having more features than ASP, because ASP

supports tags based programming whereas to work with servlet strong java

knowledge is required.

To overcome above problem SunMicro system has given a

tag based technology called JSP having all the features of

servlet to attract asp programmers.

Limitations of servlet :-o Strong java knowledge is required not suitable for non-java


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programmer placing html code in servlet is quiet complex and

error prone process.

o In servlet programming the java code business logic (html code)

and presentation logic will be mixed up.

o Configuration of servlet prog in web.xml is mandatory.

o Exception handling should be taken care by programmer.

o The modification done in servlet program will be reflected only

after recompilation of servlet program and reloading the web

application.

o No implicit obj support.

o Learning and applying the servlet is complex.

Note: - The object that is created by underlying environment…. And no

code is required to access the obj is called implicit obj…..

Note: - In servlet programming request, response, servletConfig etc.. are

container created built-in objs but not the implicit obj because we need to

write additional code to access those objs.

this, super are the implicit objs/reference variables of java application.

length, class are the implicit obj properties/member variables of java application.

Class c=Test.class;

Here “class” (the implicit member variable) creates and returns

object of java.lang.Class holding “Test” class data of the object.

In java :-

“class” is a oops terminology.

“class” is a keyword.

“ java.lang.Class” is a pre-defined class.

“class” is a built in property.

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Feature of jsp:-

Allows tags based programming.

Strong java knower is not required, so it is suitable for both java andnon-java programmers.

Gives 9 implicit objects.

Allows to separate presentation logic (html) from business logic(java code).

The modification done in jsp will be reflected without any

recompilation and reloading web application.

Configuration of jsp in web.xml file is optional. Use built in tag and also allows working with third party tag or custom

tag.

Easy to learn and use.

Exception handling is optional.

Allow to work with all the feature of Servlet.

Every “.jsp” file is called as jsp prog/jsp comp/jsp page/jsp file.

Jsp page runs based on page compilation principle i.e. every jsp page

will be converted into an equivalent servlet prog.

To execute jsp page jsp container is required. This Container supplies to jsp

page compiler to translate jsp page into equivalent servlet prog and this

servlet prog executes with the support of jsp container + servlet container.

Every server supplies 1 built-in jsp page compiler as part of its jsp container.

What is difference between servlet and jsp?

Servlet Jsp Strong java knowledge is required so suitable

for java programmers.

Strong java knowledge is not required so

suitable for both java and non-java


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Template text = ordinary text + html

Jsp page generate dynamic web page the fixed content of dynamic web page

will be generated through template text and the dynamic values will be

generated through java code of scriptlet .


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Place jspApp folder in \web apps for deployment.

Request url: http://localhost:3030/jspApp/Abc.jsp>

20-Jul-15

Q: - How many object can be there in jsp?

o

Two types of object in jsp.

1. Explicit object

It is created by programmer manually.

Eg:

2. Implicit object

Created in JES automatically.

Jsp gives 9 implicit objects.

1. out

2. request

3. response

4. exception

5. application (ServletContext object.)

6.

config7. session

8. page

9. pageContext

What is the difference between html and jsp?

http://localhost:3030/jspApp/Abc.jsphttp://localhost:3030/jspApp/Abc.jsphttp://localhost:3030/jspApp/Abc.jsp


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Html Jsp

It is client side web technology. It is server side web technology.

These programs generate static web page. These programs generate dynamic web

pages.To execute html, interpreter is needed. To execute jsp code, we need jsp

container/jsp engine.

Does not allow to place java code. Allows to place java code.

Html code is not a strictly typed code. Jsp code is strictly typed code.

Tags and attribute are not case sensitive. Tag and attributes are case sensitive.

Servlet prog/component life cycle methods are :

1. init(ServletConfig)

2. service(ServletRequest, ServletResponse)

3. destroy()

o init(), service(HttpServletRequest ,HttpServletResponse), doxxx(-) are not life

cycle methods. They are convenience methods given to programmer.

o Every jsp prog/page internally gets an jsp equivalent servlet prog/component

for execution , so there will not be any separate life cycle methods for jsp sothe servlet life cycle methods itself acts jsp life cycle methods. But different

convenience methods are given for jsp.

They are:-

jspinit()/_jspInit() will be called from init(-) life cycle

method .

_jspService(-,-) will be called from service(-,-) life cycle

method.

jspDestroy()/_jspDestroy() will be called from destroy()

life cycle method.

In tomcat server Jsp Equivalent Servlet(JES) class source file and class file for

ABC.jsp is -


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o ABC_jsp.java , ABC_jsp.class and the location is

\localhost\jspApp\org\apaceh\jsp

Here jspApp is projce name

org\apache\jsp is package name

Every JES class is

a. HttpServlet class based servlet prog

b.

Contains only _jspService(-,-), _jspInit(), _jspDestroy() methods

and does not contains jspInit(), jspDestroy() methods.

c. Extends from jsp Container supplied class which extends from HttpServlet. This

supplied calls jspInit()/_jspInit(), _jspService(-,-) , jspDestroy()/_jspDestroy()

methods from servlet life cycle methods in tomcat server this class name is

“HttpJspBase”.


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d. Template text code, scriptlet code placed in jsp automatically goes to

_jspService(_,_) methods to create and use implicit objects and etc…..

Q: - When JES class obj is created by container?

o Calls init(ServletConfig obj) on JES class object.

Since not found, init(ServletConfig) of super class (HttpJspBase)

executeds and that methods internally calls jspInit(), _jspInit()

methods.

When request processing event occurs.

Calls service(ServletRequest ,ServletResponse) on JES class obj. Since not found same service(-,-) of GenericServlet executes

This calls service(HttpServletRequest, HttpServletResponse) of HttpJspBase class.

Service(-,-) of HttpJspBase class internally calls _jspService(-,-) methods.

When Destruct event is raised:

Calls destroy () on JES class obj.

Since not found destroy () of super class HttpJspBase executes.

This destroy () internally calls jspDestroy ()/_jspDestroy () method.

“_” (Underscore) symbol in methods name indicate that they are generated

methods in JES class i.e. we cannot place same methods in JES class through jsp

page/program.

jspInit()/_jspInit(),_jspService(-,-),jspDestroy()/_jspDestroy() methods are

convince methods given by jsp api i.e. these are not life cycle methods of jsp

because they are not called by a container directly and they are called through

servlet lifecycle method internally.

When life cycle life event is occurred is called life cycle method. The method that

is called through life cycle method is not called life cycle method.


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21-Jul-15

In weblogic server JES class for ABC.jsp will be generated as _ _ABC.class and also

destroyed the .java file or JES class once the .class file is created.

Two phases of jsp execution

A. Translation phase

In this phase the jsp page/program will be converted into an equivalent servlet

source file and compiled file.

B. Request processing phase/ Execution phase.

In this phase JES class will instantiated and _jspService(-,-) method executes to

process the request and to send the response to browser.

The request given to jsp program/page directly participates in “request

processing phase” if the source code of jsp page/program is not modified whencompared to previous request and .class file of JES class is available otherwise

request given to jsp page participates in both translation phase and request

processing phase.


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Jsp container internally remembers the source code of jsp program/page for

every request until next request comes to that jsp page/program and uses the

comparison tools like Araxis or WDiff to compare both source codes.

Note: if the .java file JES class is deleted then the request given to jsp file will notparticipate in translation phase.

Note:- the modification done in the source code of JES class does not reflect to

the output.

WEB-INF and its sub folders are called private area of web application i.e. only

underlying serve/container can use the content of that web application.

If any web resource is placed inside WEB-INF then configuration of web.xml is

mandatory otherwise optional.

In some special cases we prefer to place jsp program or page in side WEB-INF

for the following benefits:-

i. To hind technology of the web site from the visitors.

ii. To avoid ugly messages displayed by jsp when we give

direct request to jsp when it is having logic to read and

display request attribute value given by servlet.

To overcome above problems place jsp program inside WEB-INF folder,

configure in web.xml file and Access jsp prog either through servlet/servlet filter.

o Example

A

/WEB-INF/pages/ABC.jsp


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A

/test

Request url

o http://localhost:3030/jspApp1/ABC.jsp (wrong)

o http://localhost:3030/jspApp1/test (correct)

22-jul-15

When jsp page outside WEB-INF, configuration file is optional

When jsp pages are placed inside WEB-INF folder its configuration in web.xml

file is mandatory.

Jsp Tags/Elements

1. SCRIPTING TAGS:-

a. Scriptlet ()

b.

Declaration ()

c. Expression ()

Note:- These tags are given to place java, in jsp. The java code placed in jsp is called script code.

2. JSP COMMENTS ()3. DIRECTIVE TAGS/ELEMENTS

a. page directive ()

b. include directive ()

c.

taglib directive ( )

4. STANDARD ACTION TAGS.

http://localhost:3030/jspApp1/ABC.jsphttp://localhost:3030/jspApp1/ABC.jsphttp://localhost:3030/jspApp1/testhttp://localhost:3030/jspApp1/testhttp://localhost:3030/jspApp1/testhttp://localhost:3030/jspApp1/ABC.jsp


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1. Scripting Tags:-

1. (a) Scriptlet:-

Standard syntax:-

Xml syntax:

...................

...................(java code)

Code placed in scriptlet goes to _jspService () method of JES class.

Variables declared in scriptlet becomes local variables to _jspService (-,-) method of jsp.

In jsp

in JES class

public class ABC_jsp extends …..

{

public void _jspService(-,-)

{

int a=20;}}

We can use scriptlet for placing request processing logic, because its code

goes to _jspService(-,-) method of JES class.

in jsp


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out.println(“sum=”+c);

%>

int b=30;

int c=a+b;

out.println(“sum=”+c);

}}

Using xml syntax:-

Welcome to jsp

Out.println(“system date “+ new java.util.Date());

While working with less than symbol “

int b=30;

if(a


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the body as ordinary text (java code), so “

But greater than symbol does not have such problem:

int a=20;

int b=30;

if(a>b).

out.println(a +” is less than”+ b);

elseout.println(b +” is less than”+ a);

N OTE : - less than symbol is not there with standard syntax and greater than symbol not goes this

problem in any syntax.

Implicit object are local variable to _jspService(-,-) method in JES class, and the code

placed in scriptlet also goes to _jspService(-,-) of JES class so we can use implicit objs in

scriptlet.

// here out and request is implicit object.

java does not support nested method support so we cannot place method definition in

scriptlet, because it becomes nested method definition of _jspService(-,-) method.

Jsp code

// it will gives error because it will become

nested method in _jspService(-,-) method.

In JES class

public void _jspService(-,-) throws

Se,IOE

{

public int sum(int x,int y)

return x+y;

}

}


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Note: - we cannot place interface definition in a method definition that mean we cannot place

interface definition in scriptlet.

But we can place class definition in the above context.

java support nested class definition, nested interface definition.

We can place interface definition inside the class and class definitioninside the interface.

1.

(b) Declaration Tag:-

The code placed in eclaration tag goes outside to _ jspService method of JES class.

So we can use this tag for global variables declaration, method definition,

class/interface definition (nested), jspInit(), jspDestroy() method

definitions and etc……

Standard syntax:-

Xml syntax:-

……. …….

Variable declared in Declaration tag will come as global variable of JES class.

In JES

In JES class

public class ABC_jsp extends ……

{

int a=10;

}

Q: - How can we differentiate declaration tag variable from scriptlet tag variable

being from scriptlet when both have got same name.


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23-Jul-15

Ans:- Use either implicit object “page” or “this” as shown below:-

We can place user defined method in declaration tag.

JSP program

{

if (x


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Implicit object of jsp cannot be used in declaration tag because implicit object

are the local variable of _jspService(-,-) method and declaration tag code not goes to

_jspService(-,-) in JES class.

By default JES class gives _jspInit (), _jspDestroy () and _jspService () method,

but we can use declaration tag support to place jspInit() and jspDestroy()

method as shown below.


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1) Complete translation phase on jsp program.

2)

Create JES class objects using 0-params constructor.

3) jspInit() methods executes.

So the first request given to jsp directly participates in request processing.

a

/ABC.jsp

1

a/abc

Note: - we need to request to jsp by using its url pattern.

Note: - jsp configuration in web.xml benefits will come only when jsp is requested through

URL pattern.

Q: - can we placed _jspInit (), _jspDestoy (), _jspService () method indeclaration tags of jsp?

Ans:- not Possible, because they become duplicate method of JES class and java does not

support duplicates.

We can place class, method, and interface definition in declaration tag, they will

become nested class or nested interface of JES.

Jsp:

JES class

public class ABC_jsp extends HttpJspBase

{

class Test{}

interface xyz{}

}


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In one jsp program we can place multiple tags in any order having only xml syntax and

mix of both.

In one declaration tag we can declare multiple global variables and we can place

multiple method definitions.

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1. (c) expression:-

Anything that returns values after the evaluation is called expression.

Arithmetic, logical, methods call comes under expression.

Expression tag evaluates the given expression and displays the generated results on

browser as the webpage content.

Standard syntax:-

Xml syntax:-

…………

We can use expression tag to display variable values.

Bad practice because we are mixing up html code and java code…

value =

Here will display variable “a” value.


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Jsp program

value :
---display

the variable “a” value.

JES class

public class ABC_jsp extends –

{

public void _JspService(-,-)

{

int a=10;

out.print(“ value:);

out.print(a);

out.pritn(
);

out.println(“result);

out.println(a*a);

}

}

The code placed in expression tag goes to _jspService(-,-) of JES class and

becomes the argument value of out.print() method. If we use expression tag effectively there is no need of working with out.println()

method jsp.

All implicit object of jsp are visible in Expression tags.

in jsp class:

Browser

Name:

In JEs class:

out.println(“Browser”);

out.println(request.getHeader(“user-

agent”));

We can use expression tag to call both pre-defined and user-defined methods but those

methods must return value.

Sum of: is

Length of is


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Date and Time:

Date and Time new java.util.Date()

Even cannot solve the “

not be solved by using CDATA

One expression tag can evaluate only one expression at a time.

If we want to evaluate more than one expression we can use String

concatenation support.

//wrong

//wong

// correct

Note:- We cannot place class definition, method definition, and interface definition in expression tags.

Procedure to jsp page based web application in Eclipse IDE?

Step-1) configure tomcat 8 with eclipse ide.

Step-2) window serverrun time environmentaddapache tomcat

8nextlocation of tomcat serverfinishok.

Step-3) create dynamic web project.

filenewdynamic web project

step-4) add first jsp to web content folder of the project.


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//get system data

java.util.Calendar c1=java.util.Calendar.getInstance();

//get current hour of the day(24 hrs formate)

int h=c1.get(java.util.Calendar.HOUR_OF_DAY);

//generate wish messageif(h


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Compiler or interpreter recognizes the comments and places white space

character in the place of commented code due to this commented code

does not participate in execution.

Jsp supports three type of comments

1.

Jsp comments ( )//hidden comments

2. Html comment() //output comments

3. java comments(// or /* */) //scripting comments.

Jsp comments are useful to comment jsp code/tags of jsp program.

These tags will be recognized by jsp page compiler.

Html comments are useful to comment html code/ tags of jsp prog.

These tags will be recognized by html interpreter.

java comments are useful to comment java code of jsp program.

Theses comment is recognized by java compiler (javac).

Comment Visibility

.jsp In JES

source

In JES

compiled

Code that

goes to

browser

Jsp comment

Yes No No No

Html comment Yes Yes Yes Yes

java comments Yes no No No

jsp comments not visible in any phase of jsp execution so they are called as “hidden

comments”

Html comments go to the output code that goes to browser so they are called “output

comments”


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Technically speaking in jsp implicit object are not there but implicit reference

variable are there pointing to various object of web application.

“config” is the implicit reference variable pointing to ServletConfig

object.

“application” is reference variable pointing to ServletContext object.

Since these implicit reference variable are local variable of _jspService(-

,-) method. We cannot use them in declaration tag code. But we can

create other reference variable accessing same object in declaration tag

by using servlet API support.

Example :-

o We can access ServletContext, ServletConfig obj in jspInit() or

other methods declaration tags as shown below.

user

scott

a

one.jsp

p1

val1


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A

/test1

30-Jul-15

page scope means item is specific to current jsp page/program.

request scope means item is visible through request and it is specific to each request.

Session scope means item is specific to each browser but it is visible in all web resources

programs.

application scope means item is visible in all web resource programs of web applicant

irrespective of any condition.

Implicit object Reference object Scope

Out javax.servlet.jsp.JspWriter (AC) Page

pageContext javax.servlet.jsp.tagext.PageContext(Ac) Page

Config javax.serlvet.servletConfig (I) Page

application javax.serlvet.ServletContext (I) Application

Request javax.servlet.HttpServletReqeuest (I) Request

Response javax.servlet.HttpServletResponse (I) Response

Exception java.lang.Throwable (C) Page

session javax.serlvet.HttpSession (i) Session

page java.lang.Object ( C) Page

The above implicit objects are not objects technically, they are reference variablespointing to various implementations class object or sub-class object that are given

above.

To know the class name of any implicit object, use getClass() method as shown

below.

Response object class name

Request object classname

JspWriter object of class name

“out” is the object of class given by jsp container extending from JspWriter (AC)

class, that class name in Tomcat is org.apache.jasper.runtime.JspWriterImpl, thisclass is actually extends from JspWriter.

JspWriter out=new JspWriterImpl();

Html to jsp to DB s/w communication


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For html to jsp communication we need to use jsp file or url pattern as href value of

tag or action attribute values of tag.

For jsp to DB s/w communication place jdbc code in jsp page/program.

In this we can get jdbc properties from web.xml file either as context

param values or as init() parameter values.


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Imp points;-

Above application involve in all the three life cycle convenience method.

We need to differentiate logic for submit, hyper-link related request generation.

Gather jdbc properties as init() parameter values from web.xml file to achieve the

flexibility of modification, for this access ServletConfig object through servlet api code

in jspInit().

For above diagram based application source code refer application-4 of page no 264 to

267.

The code placed in jsp which goes to _jspService()method in that case exception is

option but form remaining situation exception handling is mandatory.

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Placing jdbc property in web.xml file gives flexibility of modification that means we can

change username, password and etc…. details based on the change done by database

administrator.

Directive tags:-

These tags are given to provide instructions or guidelines to jsp page compiler to

generate the code in JES class.

There are 3 directive tags:-

a.

Page directive () It provides Global info to jsp page.

b. Include directive ()

It is use to include the content of destination file

c. Taglib Directive (


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session=”true”

Default is ”true”

import =”java.util.*”

No any default value.

extends=”super class name of JES”

No any default value.

buffer=”10kb”

Default is 8kb.

autoFlush=”true”

Default is true.

errorFlush=”true”

Default is true

isErroPage=”true”

Default true

isELIgnored=”false”

Default false language=”java”

Default java.

isThreadSafe=”true”

default true.

language :-

Allows to specify the language that can be used to write script code in jsp.

“java” is default or only language that can be specified there.

This attribute effect will not appear in JES class. Example

(valid)

(invalid)


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setContent :-

Allow to specify the response contentType.

res.setContentType(-) default value is “text/html” , if we have multiple values as the

“, “ separated list then final values will be applied. Eg:-

session :-

It specifies whether the implicit object session should be created or not.

Create implicit object session

Does not create implicit object session default values: true.

o Note:- We need “session” obj only when session tracking is enable otherwise not

required.

01-Aug-15

info: Given to place short description about jsp page. This helps to know about

jsp page by seeing the header section of jsp pages.

In JES class getServletInfo() method will be overridden having this short

description.

ABC.jsp

……. ………

IN JES class

public String getServetInfo()

{

return “jep page that gives emp Report”; }


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extends

Allows to specify the class that should be taken as the super class of the

JES class, but this class must extends from HttpServlet (class) and must

implements HttpJspPage (Interface), otherwise exception will be raised.

This is not an important attribute to use because every jsp container

generates proper JES class extends from the jsp container supplied super

class, So there is no need of specifying user defined class as the super

class.

Jsp

In JES class

public class ABC_jsp extends Test{

………

……… }

import:-

Given to specify the packages that should be imported in JES class. We

can specify multiple values as the “,” list of values.

By default JES class import javax.servlet, javax.servlet.http,

javax.servlet.jsp packages.

Example:

isThreadSafe:-

The jsp page that allows multiple simultaneous requests, represent

multiple threads is not thread safe jsp.

The jsp page that allows one request/thread at a time is called thread

safe jsp.

“isThreadSafe” attribute allows us to specify whether our jsp page is

thread safe page or not.


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“isThreadSafe=”true” “ makes jsp page allowing multiple simultaneous

requests, So jsp page is not thread safe.

“isThreadSafe=’false’” makes jsp page to allows one thread/one request at

a time on to the jsp page.

For this JES class implements javax.servet.SingleThreadModel(Interface).

Any class that implements javax.servet.SingleThreadModel(interface) is

thread safe because we can start 1 thread at a time on that class object.

By default jsp page is not thread safe because the default value of

“isThreadSafe” attribute is “true”.

Example:-

//jsp is thread safe.

//jsp is not thread safe.

Buffer is temporary memory that holds data for temp period.

Servlet program uses pw.println() to writer output. (PrintWriter), this PrintWriter directly give output to the response object without taking buffer support .

In jsp programming “out ” object type is JspWriter and this uses buffer support

while writing the output of jsp program to response object.

To specify the buffer size of jsp program we can use buffer attribute, this attribute

default value is 8 KB and we can specify any other value or “ none” .

//enable buffer.

//disables the buffer

What is the difference between PrintWriter and jpsWriter?

PrintWriter JspWriter

Class of jdk api. Class of jsp api

Does not support buffering Supports buffering


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Useful in servlet programming. Useful in jsp programming as the type of “out”

object.

Note: - When buffering is disable in jsp (buffer=”none”) the jsp writer internally uses

PrintWriter object to write the content.

autoflush

Flushing buffer means sending the content of buffer to its destination. In

case of jsp the destination is response object.

Jsp page automatically flushes the buffer in the following situation.

When buffer is filled up when jsp page is complete its execution,

Auto flush attribute is given to specify whether autoFlushing

should be enabled or disabled on the buffer.

autoFlush=”ture”

enable auto flushing (default value) autoFlush=”false”

disable autoFlushing.

This attribute should be used in combination with “buffer” attribute.

Example:-


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Gives exception indicating bad combo.

Does not gives exception, but not a good practice.


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isELIgnored:-

Writing java code in jsp is not industry standard but performing arithmetic and logical

operation in jsp without java code is not possible. To overcome this problem we can use EL

(Expression language).

${}

isELIgnored specified whether EL in jsp should be recognized or ignored.

Sum is :${1+2} ouput is Sum is :$(1+2) Sum is :${1+2} ouput is Sum is :3

errorPage:-

The page that executes only when exception is raised in other jsp pages is

called error page. This is useful to display non-technical guiding

messages on the browser when exception is raised.

“errorpage” attribute can be used to specify that error page in any jsp

page.

Example:

%@page errorPage=”err.jsp” %

isErrorPage:-

Makes page compiler, jsp container to take the current jsp page as error

page. This page gets one extra implicit object called “exception” to display

exception related details.

Example:

Err.jsp

Note:- This implicit object “exception “ is visible only in error page.

mailto:%25@page%20errorPage=mailto:%25@page%20errorPage=mailto:%25@page%20errorPage=


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Exception handling in jsp Or error page configuration in jsp: -

Note: Even though JES takes care of exception handling it display technical, ugly message onbrowser window when exception raised.

There are two ways to perform erropage configuration in jsp.

Local Error page configuration:-

It is specific to one jsp program/page. Use “erroPage,isErrorPage”

attribute of for this.

Global error configuration:-

Common for all jsp program/pages of web application use tag of web.xml file.


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Main.jsp

Value :

err.jsp

internal Problem . Try again !!!!

Message :

request url: localhost:3030/JspApp3/Main.jsp

We can take html page as error page but it is not recommended to use because it does

not allow using the implicit object “exception”.

The above errorPage configuration cannot be uses for servlet programming for that weneed to go for rd.forward() based error servlet configuration.

Displaying non-technical guiding messages when IRCTC website gets technical

problem in the middle of utilization. Like network failure and database crashed.

04-aug-15

Global Error Page Configuration:-

This global error page will respond for all the exceptions that are raised in multiple jsp pages of a

jsp page of a web application. Use tag web.xml file.

JspApp4

|----------------------->WEB-INF

|------->Main1.jsp |------->web.xml

|------->Main2.jsp

|------->error.jsp

java.lang.Exception

/err.jsp

//error page configuration for any exception

raised in jsp pages


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Internal problem. Try again

from Main1.jsp

Value=

From Main2

current month is:

Resource url: http://localhost:3030/jspApp4/Main1.jsp

Note: we can place multiple tags in web.xml file to configure multiple error

pages for multiple exception raised in the multiple jsp page of jsp application.

If we configure local and global error page for certain main jsp program then local

error page will be executed when an exception is raised in jsp page.

Observation about page directive tag:-

1. Page directive tag name and attribute name are case sensitive.

2.

In valid attributes are not allowed.

3. Except import, contentType attributes, no other attribute is allowed to have

multiple values as the “,” separated list of values.

4.

Except import attribute no other attribute can be repeated for multiple times with

diff values either in same page directive or in different page directive tags.

http://localhost:3030/jspApp4/Main1.jsphttp://localhost:3030/jspApp4/Main1.jsphttp://localhost:3030/jspApp4/Main1.jsphttp://localhost:3030/jspApp4/Main1.jsp


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Directive include:-

Xml Syntax:

Includes the content/code of Destination file to the code of source jsp page’s in JES class

at translation phase. Separate execution does not take place for Destination

page/file/program.

mailto:%25@include%20file=mailto:%25@include%20file=


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No JES class will be generated for B.jsp but B.jsp code will be included to the JES class of A.jsp.

Note: this tag does not use rd.include() internally.

From the beginning of A.jsp

end of jsp

from b.jsp

Note:- in the above example in the JES class of a.jsp contains the code of A.jsp and B.jsp.

Action tag:-

These tags are given to use servlet api functionalities dynamically

at run time or request processing phase to complete the

requirement.

There are two type of Action tag

a. Standard Action tag.

Given by jsp technologies directly.


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Eg. and etc……..

b. Custom action tag.

Developed by programmer or third party vendors.

Note: - Action tags contain only xml syntax to use.

Action include:-

Syntax:-

Uses rd.include(-,-) internally use to include the output of Dest file/page/program to the

output of source jsp page dynamically at runtime/request processing phase.

05-Aug-15

page=”Destination page”

flush=”true/flush” => specified whether the buffer of source jsp page should be

flushed or not before including the output of destination program /file.


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here source and destination jsp pages executes separately by generating two different

JES classes but Destination jsp page output will be included to the output of source jsp

page by rd.inclde(-,-) internally .

JapApp6

|----->A.jsp

|----->B.jsp

From the begnig A.jsp

End of

From B.jsp

What is the difference between

Directive Action


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Perform code inclusion Perform output inclusion.

Performs inclusion at translation phase so

it is called static binding or compiles time

binding.

Performs output binding/inclusion at run

time so it is called dynamic binding

runtime binding.

Does not use rd.include() internally. Uses rd.include() internally.

This tag contains both standard, xml

syntax.

Only xml syntax.

Does not allow servlet program as the

destination program.

Allows

Does not allow specifying destination page

through expression.

(error)

Allows to specifies

Not a error

It does not generate separate JES class if

destination program is jsp program.

Generates Separates JES class.

Useful when destination program is static

web resource program.

Eg:- html page.

Useful when dest prog is Dynamic web

resource program.

Eg: servlet prog, jsp prog


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Page2.jsp is same as page1.jsp but replace home.jsp with weather.jsp.

Page3.jsp is same as page1.jsp but replace Home.jsp with sports.jsp.

http://localhost:3030/jspApp7

jsp chaining/request dispatching/communication.

Taking request from client and processing that request by using multiple

jsp’s in a communication is called jsp chaining request/

dispatching/communication.

http://localhost:3030/jspApp7http://localhost:3030/jspApp7http://localhost:3030/jspApp7


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For this we can use / tag.

In this changing source jsp page and the destination jsp use same

request, response obj so the request data coming to source jsp is visible

and accessible to destination jsp.

====> perform forwarding request operation

==> perform including response operation .

o Perform forwarding request operation by using rd.forward(-,-) internally. It

discard the output of source jsp page and send only the output of

destination page to browser through source jsp page as final response. It is

recommend to place in source jsp page as a conditional

statement to execute.

Syntax:-

o Note: there is no directive forward tag.

A.jsp

from the start of A.jsp

From end of A.jsp

B.jsp

form B.jsp

Date and time:

In servlet programming the statement placed after rd.forward() in source servlet

program will be executed but there html output will be discarded.


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In jsp programming statement placed after tag will be not be executed

because in the JES class of source jsp “return” statement will generated followed by

rd.fordward().

In the above application separate JES class for A.jsp and separate JES for B.jsp will

generated. But rd.forward() will be utilized internally to forward the request.


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Q: - Why there is no directive forward tag?

Directive tag performs code inclusion at translation phase due to this the output

discarding become not possible so there is no directive forward tag;.

Can be used as the sub tag of /

07-Aug-15

Some points are left :-

A.jsp

//val1 is param

values //val2 is

paramvalue

B.jsp

Additional req param values:


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Bill.jsp uses tag to forward the control to discount.jsp and it also uses

jsp:param tag to pass bill amount to Discount.jsp

Refer page: 273-4 for exercise

Send redirect:-

There is no tag in jsp to perform send re

direction. So we need to write response.sendRedirect() method in source jsp page as

shown below……..

Test.jsp

If source jsp page uses sendRedirection to communicate with destination then it talks

with its destination by having one network round trip with browser. So this concept is

useful when destination are remote internet website and un-known technology

websites.

http://www.google.co.in/http://www.google.co.in/http://www.google.co.in/http://www.google.co.in/


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“application” attribute scope is application scope i.e they are visible with in the

application.

“request” attribute created in A.jsp is accessible in B.jsp, C.jsp programs.

“session” attribute created in A.jsp by getting request from browser b1 is

accessible in other jsp only when they request from same browser b1.

“application” attribute crated in A.jsp is accessible in all jsp’s irrespective any

conditions.

Instead of using “request”, “session”, “application” objs separately to crate request scope,

session scope, application scope attribute respectively we can use single

“ pageContext ” obj to crate all the scopes of attributes (4 scopes: page, request,

session, application)

To create “pageContext” attribute use setAttribute(-,-) method.o pageContext.setAttribute(“attr1”,”val1”);//here attr1 is attribure name and val1 is value.

creates attr1 as page scope attribute.

o

pageContext.setAttribute(“attr2”,”val2”,pageContext.SESSION_SCOPE);

// pageContext.SESSION_SCOPE to set scope.

creates attr2 as session scope attribute.

To modify “pageContext” attribute value use setAttribute() methodo

same setAttribute(…) method.


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To read “pageContext” attribute values use getAttribute(-) method.

String s1=(String)pageContext.getAttribute(“attr1”);

//get attr1 values from page scope

String s2=(String)pageContext.getAttribute(“attr2”,pageContext.SESSION_SCOPE);

//get attr2 vales from session scope

To remove “pageContext” attribute use removeAttribute(-) method.

pageContext.removeAttribute(“attr1”);

pageContext.removeAttribute(“attr2”),pageContext.SESSION_SCOPE);

To find attribute use findAttribute(-) method.

String s1= pageContext.findAttribute(“attr1”);

searches and gets given attribute in multiple scope.

What is the difference between “getAttribute” and “findAttribute” method?

“getAttribute” search for the given attribute only in

the specified scope.

“findAttribute” searches for the given attribute in

multiple scope in an order (“page”=>

“request”=>”session”=>”application” scope.

Example application:-

Give first request to A.jsp and other request and other jsp pages from same or different browser

windows to absorb scopes of the attribute.

Instead of using “pageContext” object to crate “ page” attribute scope it is recommendedto use instance variable that is specific to each jsp page.

Q: - How can we pass data between various web resource programs of the web

application?

If source jsp page and destination program reside in the same web application


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1. If source jsp and destination program uses same request object .

a)

“request” attributes

b) “pageContext” request scope attribute.

c) As additional request param values using tag.

2. If source jsp and destination program gets request from same browser .

a)

“session” attributes

b) “pageContext” session scope attributes.

3. If above two conditions are not satisfied

a)

“application” attributes.

b) “pageContext” application scope attributes

If source jsp page and destination program reside in two different webapplication

Append query string to url of res.sendRedirect(-) method.

res.sendRedirect(http://www.google.co.on/search?p1=val1&p2=val2);

Session tracking in jsp:-

Same as servlet but we can use implicit object “session” for session tracking.

10-Aug-15

This tag are given to display applets on browser.

This tag allow one tag to display error message when browser does

not support applets.

Applets are outdate because of their performance so there is no much important of this

tag moreover current browser need plugin to display applets.

JspApp11

|------->webcontent

|------->plugin.jsp

|------->TestApp.jsva/.class

(applet)

http://www.google.co.on/search?p1=val1&p2=val2http://www.google.co.on/search?p1=val1&p2=val2http://www.google.co.on/search?p1=val1&p2=val2http://www.google.co.on/search?p1=val1&p2=val2


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If applets are used to display/design animation/logos then is useful. This

tag attributes are:-

type->”applet/bean”

code->Applet class name

codebase-> folder where the applet class is available.

width->

For example application -06 of page 269

Note: - after the arrival of adobe, flex, flush and javaFx the industry is not using applets to

design logo.

tag internally uses or tag and tag

internally uses tag.

o (for more info search in workspace “pluging’ and analysis code)

To pass additional data as params from “ plugin.jsp” to Applets we can use

, tag.

Pluging.jsp

TestApp.java

public class TestApp extends Applet

{

Pubic void paint(Graphics g)

{


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String name= getParameter (“orgName”);

//super class method can directly called in sub class directly getParameter() is paint class

method.

g.drawString(name,200,200);

}}

Java bean is a java class that is developed with some standards.

Setter methods/setxxx(-,-) methods are usefule to write data to bean property.

Getter methods/getxx(-,-) are useful to read data from bean property.

The javaBean whose object holds input value given by end user nothing but form data is

“VO” class.

The java bean whose obj holds data to transfer from one resource to another resource is

called DTO class. This class implemetns Serilizable(interface).

The java bean whose object holds data as required for the persistence operations is

called BO class.

Java bean is always useful as heloper class to transfer data from one layer red to another

layer.

For servlet to javaBEan communication we need to create java bean class obj is serletand cll various setXXX(0,0) and getxxx(-,-) methods.

For jsp to jsvaBean communication we can use

o , , , tags …..

Example java Bea

------

Public class StudentBean

{

Private int sno;

Private String name;

Private String address;

{

//getter and setter

}}


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Useful to create /locate bean class object.

o

Attributes

“id ””become reference variable name of bean class object”.

“class” ”fully qualified bean class name”.

“scope””page/request/session/application”

Default scope is page.

“beanName” ”Allows to specify the extra logical name”.

“type” “allows to specify the super class name as reference type”.

Example:-o

Create “StudentBean” class object referred by “st” and keeps in session

scope having the attribute name “st”.

If(pageContext.getAttribte(“st’,pageContext.SESSION_SCOPE)==null)

StudentBean st=new StudentBean();

pageContext.setAttribute(“st”,st,pageContext.SESSION_SCOPE);

}

else

{

St=pageContext.getAttribute(“st”,pageContext.SESSION_SCOPE);

}

Example:-

com.nt.Person” is refrence type and com.nt.studentBean is object type. Note:- StudentBean must be the sub class of Person.

Note: if “type” attribute is not specified then the “class” attribute values acts as refrence type

and object type.


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11-Aug-15

calls setxxx() of java bean class to set given values to bean properties.

o

Attributes:-name=” “ Bean id(id attribute values of tag)

property=” “bean property name or xxx or setxxx(-) method.

Value=” “value of bean property.

Param=””->request param name whose values should become request .

. param value.

Note:- use either value or param attributes at a time.

Eg1:- java resources|---------src

|---------com.nt

|---------studentBean.java

|---------webcontent

|---------setValues.jsp

|---------getValues.jsp


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|---------WEB-INF

|---------web.xml

For above code based example application refer application-7 of page no 270.

Loacalhost:3030/jspapp12/setvalue.jsp

Getvalue.jsp

JavaBeans of web application need not be configured in web.xml file.

There are three type of bean properties:-

1. Simple Bean properties

o Allow to set one values at a time.

Eg:

private String name;

public void SetName(String name){

This.name=name;

}

Public string getName()

{

Return name;

}

2. Boolean bean properties.

Allows to set 1 boolean value at a time

Eg:-

private boolean married;

public void setMarrired(boolean married)

{

This.married=married;

}

Public boolean isMarried()

{

Return married;

}

3. Indexed properties

Allows to set multiple values to each property.Eg:-

Private string color[];

Public void setColors(String [] colors)

{

This.colors=colors;

}

Public String[] getColors()


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{

Return colors;

}

The above tag useBean setProperties and getpropteries are useful when jsp want to send

multiple values of form page to service class or DAO class in the form of Bo or DTO class or Vo

class object.

DAO uses Bo class object.

Service class can use either BO class or DTO class object.

Gudces

12-aug-15

Java web application contains

Request data gathering

Reading request parameter, header, miscellaneous details)

Form validation logic.

Checks format, pattern of from data(main logic that generate

result)

B.logic/service logic/request processing logic

The logic that gives user interterface.

Presentations logic

Logic that performs database operation example jdbc code.

Session management logic

Cookies, hidden form fields and etc…)

Middleware services.

Additional services like security, logging, pooling and etc..)

Model-1 Model-2Here we use either only servlets or only jsp todevelop java application, i.e if servlets are usedin web application the jsp will not be used any

vice versa.Model-1 architecture is mainly using jsp


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application.Here every main web resource pro likeservlet/jsp program contains all the logic of

web application development.

Model-1 architecture:-

Working with only jsp or servlet comes under model architecture.

The application that we have developed so far using only servlet or jsp comes under

model one architecture.

Disadvantage of model-1 architecture:-

Since every web resource program contains multiple logic we can say there is cleanseparation between logics.

The modification done in one logic will disturb the other logics.

Parallel development is not possible, so the productivity is very poor .

Enhancement and maintained of the project becomes very complicated.

Certain middle ware services must be developed by the programmer manually.

This improves burden on the programmer.

Advantages:-

Knowledge on only servlets or only jsp is enough to develop web application.

Since parallel development is not possible, so multiple programmers are not required.

Note:- Doing more work in less time with good accuracy is called productivity.

Note:- model1 is good to develop small scale java web application less than 10 pages.

MVC – MModel Layer represents B.logic +persistence logic. (Accountants


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(Generate Data)

V View layer represents presentation logic (Beautician)

Ccontroller layer represents integration logic. (super viser)

Integration logic controls and monitors all the activities of application development. This

logic takes the request from client, passes the request to model comp, gathers the results

from model comp and passes the result to view comp.

In MVC1 single servlet/jsp component contains view, controller layer logics and separate

components will be taken as model components.

In MVC-2 we Take separate jsps as view layer comps, separate servlet as controller comp

and separate other components as model layer components

Since we are write model layer logic in separate logic in separation components.

It give clean separation between logics then go for MVC-2 arch

MVC-1 architecture is good to develop medium size application. 10 to 20 pages.

Advantages –

Since there are multiple layer we can get clean separation between logic the modification

done in one layer logic does not affect other layer logic. Provides easiness in enhancement, maintenance of the web application.

Parallel development is possible so productivity the productivity is good (view,

controller logics and model layer logics can developed parallel)

It is defacto standard to develop large scale java websites.

While using EJB, spring in Model layer we can use built in middle ware services.


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Disadvantage-

Knowledge on more technologies is required.

For parallel development more programmers are required.

13-aug-15

MVC-2 rueles/principle

Every layer is designed to have specific logic so just place those logic and don’t place

any additional logics in each layer.

All the operation of the application must be handled under the control of controller

servlet.

They can be multiple resources in model layer and view layer but we must take single

servlet or servlet filter as controller.

The view layer component should not interact with model layer comp

directly, thy must interact with each other through controller servlet.

The controller servlet should have ability of trapping request wrapping request data to

object and validating request data and etc…operations.

Can we change the roles of various technologies uses in MVC-2 architecture based

application?

Servlet as view:-


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Presentation logic of web application changes as regular interval and changing code in

servlet programing needs recompilation of servlet and relocating of web application.

The modification done in jsp will reflect directly, so jsp are good as view.

Jsp as controller:-

Write java code in jsp is not industry standard but as a controller jsp should have java

code to interact with model components. Placing java code in servlet to interact with

model component is good practice so use servlet as controller.

Hibernate app/EJB comp/spring app as view, controller layer

components:-

They cannot take requests and they cannot response, so they cannot be taken as view,

controller layer components.

Project:-

Add rotator. This application display advertisements in the web pages.

There are three type of adds :-

a) Sequential advertisements

Comes one by one in a sequence.

b)

Random advertisements

Displays the adds randomly

c) Direct advertisements

Displays adds based on the actions of programs.

Eg: while searching for seven wonders it displays adds about tours

and travels)

Our AddRotator application

a) Develop based on MVC-1 architecute(jsp java bean/class)

b) Should display random add for every 2 seconds.

c) Should add as graphical hyperlinks


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jspApp13:

|------->java resources

| |------->com.nt

|------->Rotator.java (bean class)

|------->webcontent

|------->Addrotator.jsp

|------->1.jpg, 2.jpg, 3.jpg

|------->WEB-INF

|------->web.xml

Refer app-8 of page

no-271

14-Aug-15

Mini project discussion

We can send only serializable object over the network. We can say the obj is serializable

object only when the class of the Object implements java.io.Serializable interface.

ResultSet obj is not a serializable object so we cannot send that object over the network.

To overcome that problem use

RowSet instead of ResultSet.

Note- all RowSets are serializable obj by default.Note: very few jdbc driver support RowSets.

Copy ResultSet object record to collection and send that collection over the network.

Note: - all collections are serializable object by default.

Note: - if you want to perform only read operation on the collection then use non-

synchronization data structure that gives performance. If want to perform both read

and write operation on collection then use synchronized data structure for thread

safety.

Understanding problem to copy records of ResultSet to the elements of ArrayList.

Each element of ArrayList allows one object at time but each record of ResultSet

contains multiple value/objects. So we can’t place each record of ResultSet to each

element of ArrayList


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To overcome this problem copy each record to one class of BO class object and that BO

class object to ArrayList element.

Note:- In order to send collection over the network the object added to collection must

also be taken as serilizable object.

BO class

public class Student implements java.io.Serializable

{

private int sno;

private String sname;

prviate String sadd;

//setter and getters}

ArrayList al=new ArrayList();

ResultSet rs=st.executeQuery("select * from studetn"0;

while(rs.next())

{

// copy each record of ResultSet to Eache Bo calss object.

Student st=new Student();

st.setSno(rs.getInt(1));

st.setSname(rs.getString(2));

st.setSadd(rs.getString(3));//add Each BO object to each ArryList element

al.add(st);

}


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MVC2 Architecture based Mini project:-

M---->Model ---->java class(B.logic +persistence logic)

V---->view ---->jsp/html (presentation logic.)

C---->Controller----> integration logic. (servlet)

17-aug-15

Key points:

The above application uses BO class (java bean) support to transer the records of

ResultSet to ArrayList and sends this ArrayList

Over the network to servlet.

Servlet uses rd.forward(-,-) to pass control to jsp program of view layer

Uses java script for form validation and also for submitting request.

Servlet program identifiers the button that is used to submit request based on the values

sent from hidden box.(source)

Servlet program pass the ArrayList obj as request attribute values to jsp program to pass

the result given by Model layer java class to jsp program.

Provision is placed to take the print out the web page.

Provision is placed to download the excel sheet.

For source code project given in page no-300


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18-Aug-15

Mini project 2:-

The process of sending the files of client machine file system to server

machine file system is called file uploading and reverse is called file

downloading.

There are two types of file downloading:-

a) Response downloading:-

Here the output of web resource program will be send to browser

as downloadable file.

b) Resource downloading:-

Here the resource (file) of server machine file system will be

downloaded to browser.

We use java zoom API for file downloading. In real time the

uploaded files will not be saved in directly in DB table cols. They

will be saved in server machine file system and their address path

will be saved in DB table cols as string values.

o Eg: www.youtube.com

19-Aug-15

For more mini project refer page-285 to 300 of the booklet.

Custom tag library(custom jsp action tag)

Writing java code in jsp is not industry standard we should always develop jsp as

scriptlet jsp page for this we should place only tags in jsp and we should avoid scriptlet,

expression, declaration tags.

http://www.youtube.com/http://www.youtube.com/http://www.youtube.com/http://www.youtube.com/


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Develop java code less jsp gives following advantages.

a) Increases readability of jsp.

b)

Improves the reusability of java code represented by tags.

c) Both java and non-java programmer can work easily and etc……

To develop jsp as scriptlet jsp we can use following tags.

o Html tag, jsp built-in tags, custom action tags, JSTL tags and third party supplies

tags.

Custom jsp Tag library:-

Terminology:-

a) Jsp Tag Library

It is a library that contains set of jsp tags. It is similar to java package.

There are three type of tag library.

a)

Jsp built-in tag libraries

b) Jsp custom tag libraries

c) Third party jsp tag libraries.

b) Tag handler class:

The java that extends from javax.servlet.jsp.tagext.TagSupport class and defines the

functionality of jsp tag.

a) TLD file

The xml file with extension .tld having the cfg jsp tags of jsp taglibrary like tag name,

tag handler class name, attributes and etc info.s

20-aug-15

Procedure to develop custom jsp tag library

Step-1) Design Jsp Tag library.


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HCLTaglibrary

|------->,

Step-2) Develop tag handler classes in WEB-INF/classes folder

xyzTag.java

Package tags;

Public class Xyz extends TagSupport

{

Public class XyzTag extends TagSupport

{

//logic related to open tag, attributes and body processing

}

Public int doEndTag()

{

//executes for tag.//logic related to closing tag.

}

}

ABCTag.java

===========

public class ABCTag extends TagSupport

{

public int doStartTag()

{

:::::::::::::::::::::::::::::

}

}

Step-3) Develop tld file having configuration of jsp tags.

Note:- step-1 to step-3 indicates the development of jsp tag library.

WEB-INF/hcl.tld (xml file ===> Sample cole)

ABCABCTag.class

XYZXYZTag.class

Step-4) configure jsp tagLibrary in web.xml file having taglib uri.

(d)


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demo//here demo is taglib uri

/WEB-INF/hcl.tld// /WEB-INF/hcl.tld is the name and

loaction of tld file (e)

Step-5) Use the tags of jspstaglibrary in jsp page/program.

Test.jsp

=========

---c----------

(b)(prefix taken

(a)

Note: - step-4 and step-5 talks about utilization of jsp tag library.

is useful touse jsp taglibraries in the jsp pages/program.

Follow of execution:

a)

In the execution of jsp the total h:abc tag is encountred

b)

Form that tag prefix “h” will be taken.

c) Based on the prefix the tag lib uri will be gathered.

d) And (e) Based on configuration done in web.xml file tld file will be gathered by using

taglib uri.

f) From tld file the name of the tag handler class will be gathered.

g) Containers calls doStartTag(), doEndTag() method of tag handler class. As call back

method to generate the output.

h) the generated output goes to browser through response, web server

En every tag handler clas we get the pageContext as


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doStartTag(), doEndTag() are the call back methods of Tag Handler class. jspContainer

automatically calls these methods for every Open tag, closing tag encountering.

These method returns int constants giving instruction jsp container. They are

SKIP_BODY skip the evaluation of the tag.

EVAL_PAGE Evaluate the remaining jsp page.

SKIP_PAGE Skip the evaluation of total jsp page.

EVAL_BODY_INCLUDE Evaluate the tag by including the body.

For example application for custom jsp` tag library development refer page no:-282 of the

booklet.

The prefixes will use in jsp tag library are very useful to differentiate two tags belongingto two different tag library having same name.

21-Aug-15 EL( Expression Language)

In order to avoid java code in jsp we can use EL. It is specially useful to

perform arithmetical and logical operations without java code. It can be

used on template tag or it can used with any jsp tags like JSTL tags, customtags and etc………

Syntax:-

${……………}

o Ignore EL

o Does not Ignore EL

EL operators:Same as java

ELImplcit objects:-

Param

paramValues

header,

headerValues


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cookie

initParam

requestScope

pageScope

SessionScope

appliationScope and etc…….

Note:- These object can be used along with a implicit object of jsp.

Sum is : ${4+5}

4>5? ${4>5}

request param usname value: ${param.uname}

Current browser name: ${header['user-agent']}

Request Attribute value:${requestScope.course}

Cookie name ${cookie.JSESSIONID.name}

Cookie value ${cookie.JSESSIONID.value}

For related info on EL refer page no 347 to 357

JSTL (jsp standard tag library):-

Writing java code in jsp is not industry standard, but built in tags are not sufficient,

custom tags development are very complex.

El is having limited scope of utilization in order to all these problems we can use JSTL.

JSTL tags are designed by SunMicro system as specification but all servers vendors are

providing the implementation in their own ways, so we can use all JSTL tags in a

common ways in our jsp pages……

If you work with JSTL tag write from variable declaration to database connectivity and

formatting of data can be done through tags.

23-aug-15 Annotations based servlet programming

Data about data is called Meta data. It is all about gathering info about the already

available info.


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In java we can use multiple portions for MetaData operations.

a)

Using comments

//hold s person age

Private int age;

b)

Using modifier

Private static final int PI=3.14;

c)

Using xml file

Xml file gives good flexibility of modification, but gives bad performance.

Because to read and process xml file we need heavy weight xml parser.

d) An no ta tio ns :-

Annotations are java statement that can be place in java source code

directly.

Annotations give good performance but gives bad flexibility of

modification.

Resource configuration is also one kind of Meta data operation.

Eg: configuration of servlet program in web.xml file.

Annotation syntax:--

@(param1=val1,param2=val2,……….)

In java we have two types of annotations:-

a) An no ta tio ns fo r Do cu me nt at io n

Useful for api documentation.

Eg:- @author, @return, @param, @see, @since, and etc….

b) An no ta tio ns fo r program mi ng (from jdk 1. 5)

@Override( it indicate method is overridden method), @suppresswarning(it is

used to suppress warnings from compiler )…….


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Servlet Annotations:-

Given from servlet api-3.0 (computable servers are : Tomcat 7,8)

Alternate to web.xml file based configuration like servlet configuration, filterconfiguration……….

If you configure certain thing by using annotation and xml file then the configuration

done in xml file will be overridden with annotation configuration or both are merge.….

As of now limited annotations are given in servlet api and they are adding annotations

in api incrementally.

o Servlet 3.x api pkg are

Javax.servlet, javax.servlet.http, javax.servlet.annotation, java.servlet.descirptor.

The servlet Annotations are :

@WebServletto configure servlet program

@WebFilterto configure servlet filter prog

@WebInitParam to configure servlet init param

@WebListenerto configure servlet listener

@HandlerTypes

@ServletSecurity

@Multipartconfig (Relegated to servlet security configurations

@HttpConstaint

@HttpMethodConstaint

To know the target area of applying annotation we can see api documentation of that

annotations and all the servlet annotations are class level annotation.

Application -19 of page 142.


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Note: - While working with annotation if you specify value without parameter name

then that will go to parameter whose name is value.

23-Aug-15

JSTL =>

Jstl is providing 5 jsp tag libraries having set of tags in each tag libraries with tld files .

They are _

Core:- For Basic operations like variables decl, conditions,……

SQL ;- For DB interactions

XML :- for xml processing

Formatting : to Enable I18n (data formatting, number formatting )

Functions: TO manipulate Strings.

Every jstl tag library is identified with its fixed Uri which can be collected

from list

Corec.tldhttp://java.sun.com/jsp/jstl/core

SQLsql.tld /sql

Xmlx.tld /xml

Formattingfmt.tld /fmt

Functionsfn.tld /fn

All these tag liberties related tag handler classes, tld file and etc.

Are available in every server in the form of jar file…

They jstl.jar, standard.jar (Get form Tomcat installation).

For information about various jstl tag libraries and its tag, attribute refer page no -311

to 314.

JSTL core Tag Library:-


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Given for basic operation to be done using tags like variable Declaration, conditions,

iterations and etc……

----……> like expression tag ( to display data).

----……> to declare variable with value in a scope.

----.> to remove variable from a scope…

JSTLAPP-1

|---->webcontent

|---->Test.jsp

Jars: jstl.jar, standard.jar….(deployment and assembly)

//”msg” is variable name “hello” is

value and “session” is scope “el” representing variable name

Message:

Message:

For more example on jstle Core tag library refer – 344 and 345.

C:if--->for if condition

C:forEach---> to iteration

C:forTokens>--->for String tokenization

, ---> for switch case.

--->for exception handling.

// here raised exception is stored in “e”

int a=Integer.parseInt("10");


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-----> to import the content of destination resource to the source. (it is like

-----> to define url to use in url tag

From Main page:-


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Jstl sql tag library is not really popular in real time because in real time jsp will be used

in the view layer(a/c to mvc2 architecture) and persistence logic is not required in the

view layer.

Formatting tag library:-

This tags are given to format data, number, label, according to local supporting according to

internalization (i18n).

Local means language +country.

o Eg:- en-us

o Fr-FR

o De-DE

o

Hi-IN ( hindhin as it specaks in india)

Making our application working for diff locals is called endabling I18n. Due to this our app

works for different customers of diff lcaes.

The formatting tags library tags are:

o poings to one local

o points to properties file (bundle file)

o TO display message according to label

o To format number

o

-> to format datao End etc…..

jstlApp2

|----->java resources

|----->src

|----->myfile.properites(base file)

|----->myfile_de_DE.properties(for Germany)

|----->myfile_fr_FR.Properties (for French)

|----->web content|----->Test

Note: - The base file name in all properties file must be same .

The keys in all properties file are must match and u can gather values by using

google translator.


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Example:-

MyFile.properties:-

wismessage =”Good morning”.

Myfile_fr_Fr.proerties:-

Wishmessage=”some this called “

TestFormate.jsp

Uri= ………………………./core

-----------------------/fmt

30-Aug-15

Security in web application:-

It is middleware service/secondary service that protection to our application. Security deals

with.

a) Authentication:-

Check the identity of the user through username, password thumb impressions,

iris and etc….

b) Authorization:-

Checks the access permission of a user to access certain resources of the project.

Do not assign access permission directly to user names. Always assign access

permissions to user roles. Roles are like designation.

c) Data Integrity: -

Not allowing data being tampered while sending the data over the network is

called integrity. Rs 1000 should not become Rs 10000 while sending over the

network.

d)

Data Secrecy: -

Data must be accessed by the user for which it is intended to use i.e one usershould not use other users data. More ever data should send over the network

in an encrypted form.

Rajaoriginal data

Asbbckdb after encryption


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raja after decription.

Only sender and receiver know inscription algorithm any one cannot misuse our data.

Servlet specification supports 4 modes of authentication:-

BASIC

DIGEST

FORM

CLIENT-CERT

We can enable the above authentication modes of security either in declarative mode or

programative mode.

In programmmitive mode we mainly write java in servlet and jsp program for authentication or

authorization.

In declarative approached everything will placed through xml file.

LDAP is providing password incription mechanism.(Light weight directly

access protocol.)

Security Realm is a context that maintains username, passwords which should be validated

while performing authentication.

We can configure security Realm.

a) Directly in the server.

b) As a flat file linked with the server.

c)

As database software linked with server.

d) As LDAP server linked with server.

LDAP Lightweight directory access protocol.

In LDAP the passwords will be stored as encrypted, so we cannot see the

password and modify the passwords, but we can reset the passwords.

If no name is given to realm the default name : myrealm.

Check:

Creating security realm in tomcat server directly(option-1)

In tomcat_home/conf/tomcat-users.xml


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Basic mode of authentication:-

Uses Base64 encoding algorithm. Makes browser to give a standard dialog box asking

username, password. It works with all browser software

1 browser gives request to servlet.

2Container takes the request and notices that server is security enabled so request will not go

to servlet and container generates 401 status code based error response to browser.

3 upon receiving 401 status code response browser displays dialog box.

4 Dialog box submit the request having user name and password.

5 Container takes the request and validates user name, password against security realm if

found valid request goes to servlet.

6& 7 servlet process the request and sends response to browser.

For example basic/digest model refer:- page no:- 168, 169 application:- 30

DIGEST:-

Uses MD5 (Message digest) algorithm for encoding. Same as BASIC but browser gives a

different dialog box. Only few browsers and servers support this.


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On form model:-

It is same as basic model but allows the user to form page asking user for username and

password instead of regular dialog box. Similarly allows to configure error page that should

displayed when authentication fail. All these configuration should be done in web.xml file’

By designing above from page the username text box should be j_username and password text

box should have name j_password and the action url must be j_security_check because the

servlet container receive the form data for authentication.

For example application on form page authentication page no:- 169, 169 application:- 301

Allows to configure digital certificate that are generated using some algorithm like RSA, varisign

and etc…

We configure this digital certificate with server by specifying https protocol to be used.

We cannot use this technique for authorization and authentication only for encryption by

sending data over the network so this technique can be combined with other technique.

https mean http over SSL. (Useful to establish secured connection between browser and server.

Procedure to work

1. Create digital certificate by using RSA.(Rivest, Sameer, Adalmen)

2. Ssl contains information about info about site and location and

etc………

How it works

o Browser gives request to server to an web resource program using https protocol server

sends digital certificate to browser browser recive install and digital and now

onwards the data send onward data send by client will be encrypted based on digital

certificate algorithm.

example:-

step-1) create digiatal certificate using RSA

c:\users\NIT> keytool – genkey – alias NIT – keyalg RSA

Note :- the above tool generate .keystore file as digital certificate in c:/users/nit folder. (nit is windows

user name)

o Configure the above digital certificate to tomcat server. By enabling https protocol.

o In \conf\server.xml


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//protocol="Http/1.1"

Protocol=”org.apache.coyote.http11.Http11NioProtocol”

port = "8443" maxTHreads="200"

scheme="https" secure="true" SSLEnabled="true" clentAuth="false"

keystoreFile="c:/users/nit/.keystore" keystorePass="rajaraja"sslProtocol="TLS"/>

Step-3) starts the server:

Steep-4) Requests any web application of web server using http as shown below receive

install digital certificate.

/docs/ssl-howto.html#Indtrduction_to_SSL .

Step-5) https://localhost:8443/voterApp/input.html

natraj jsp

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