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Trong bi ny mnh s i su ni r v Intent, ph n c bn v ng vai tr r tquan tr ng trong l p trnh ng dng Android.

Khi nim v Intent:

Theo nh ngha ca Google, Intent l mt miu tv mt ho t ng c n cthc hin. Cn ni mt cch n gin v dhi u hn, Intent l mt c c u chophp truyn thng ip gia cc thnh phn ca 1 ng dng v gia cc ng dngvi nhau.

Cc thuc tnh c a Intent: - action : l hnh ng c thc hin, vd : ACTION_VIEW, ACTION_MAIN

- data : l d liu s c x l trong action, thng c di n t l mt Uri(Uniform Resource Identifier, tham kh ohttp://en.wikipedia.org/wiki/Uniform...rce_Identifier hi u r thm chi ti t).

VD:ACTION_VIEW content://contacts/people/1 - Hi n th thng tin v ngi vi mdanh 1ACTION_DIAL content://contacts/people/1 - Hi n th mn hnh gi n ngi vi

m danh 1 ACTION_DIAL tel:123 - Hi n th mn hnh gi vi s gi l 123

Ngoi ra cn c 1 s thu c tnh m ta c th b sung vo Intent: - category : b sung thm thng tin cho action c a Intent. VD:CATEGORY_LAUNCHER thng bo s thm vo Launcher nh l mt ng dng

http://en.wikipedia.org/wiki/Uniform_Resource_Identifierhttp://en.wikipedia.org/wiki/Uniform_Resource_Identifierhttp://en.wikipedia.org/wiki/Uniform_Resource_Identifier

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top-level- type: ch r kiu ca data- component: ch r thnh phn snhn v x l intent. Khi thuc tnh ny cxc nh th cc thuc tnh khc s tr thnh thuc tnh ph .- extras: mang theo i tng Bundle ch a cc gi tr b sung.

VD:ACTION_MAIN v CATEGORY_HOME : tr v mn hnh Home ca Android (khib m nt Home ca di ng)

Phn lo i Intent: Intent c chia lm 2 loi:- Explicit Intents : intent c xc nh thu c tnh component, ngha l ch r thnh phn snhn v x l intent. Thng thng intent d ng ny s khng b sung thm cc thuc tnh khc nh action, data. Explicit Intent thng c s dng khi chy cc activity trong cng 1 ng dng.- Implicit Intents: Intent khng ch r component x l, thay vo n b sungthng tin trong cc thuc tnh. Khi intent c gi i, h th ng sda vo nhngthng tin ny quy t nh component no thch h p nh t x l n.

VD:ACTION_DIAL tel:123 thng thng s c h th ng giao cho activity PhoneDialer m c nh ca Android x l.

Mt s action th ng s dng trong Intent: ACTION_ANSWER - m Activity x l cuc gi ti, thng l Phone Dialer caAndroid

ACTION_CALL- m 1 Phone Dialer (m c nh l PD ca Android) v ngay lp tcthc hin cuc gi da vo thng tin trong data URI ACTION_DELETE- m Activity cho php xa d liu m a ch ca n cha trongdata URIACTION_DIAL - m 1 Phone Dialer (m c nh l PD ca Android) v in thng tinl y t a ch cha trong data URI

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