読むと怖くないdagger2

読むと怖くないDagger2

kyobashi.dex #1

プロフィール

釘宮愼之介 / @kgmyshin

Androidエンジニア

福岡県福岡市南区野多目出身

この資料の目的

Dagger2で生成されるソースを読んで、

動きを理解する

今回話さないこと•DIとは

•Dagger2の使い所

•どういう構成にするか

•DaggerとDagger2の違い

今回話すこと

ひたすら生成されたソースを見て

裏でどういう動きをするのかを見る

Target Annotation•Component

•Module

•Singleton

•Inject

•Scope

Target Annotation•Component

•Module

•Singleton

•Inject

•Scope 時間的に無理でした

Case 1 Minimum

public interface Bread {}

public class Chokokorone implements Bread {}

@Component(modules = BreadModule.class) interface BreadShop { Bread bread(); }

@Modulepublic class BreadModule { @Provides Bread provideBread() { return new Chokokorone(); } }

BreadShop shop = DaggerBreadShop .builder() .breadModule(new BreadModule()) .build();

Bread bread = shop.bread();


Bread bread = shop.bread(); // Chokokorone

Generated Codes• DaggerBreadShop

• BreadModule_ProvideBreadFactory

@Generated("dagger.internal.codegen.ComponentProcessor") public final class DaggerBreadShop implements BreadShop { private Provider<Bread> provideBreadProvider; private DaggerBreadShop(Builder builder) { assert builder != null; initialize(builder); } public static Builder builder() { return new Builder(); } public static BreadShop create() { return builder().build(); } private void initialize(final Builder builder) { this.provideBreadProvider = BreadModule_ProvideBreadFactory.create(builder.breadModule); } @Override public Bread bread() { return provideBreadProvider.get(); } public static final class Builder { private BreadModule breadModule; private Builder() { } public BreadShop build() { if (breadModule == null) { this.breadModule = new BreadModule(); } return new DaggerBreadShop(this); } public Builder breadModule(BreadModule breadModule) { if (breadModule == null) { throw new NullPointerException("breadModule"); } this.breadModule = breadModule; return this; } }}

return provideBreadProvider.get(); } public static final class Builder { private BreadModule breadModule; private Builder() { } public BreadShop build() { if (breadModule == null) { this.breadModule = new BreadModule(); } return new DaggerBreadShop(this); } public Builder breadModule(BreadModule breadModule) { if (breadModule == null) { throw new NullPointerException("breadModule"); } this.breadModule = breadModule; return this; } }}

@Generated("dagger.internal.codegen.ComponentProcessor") public final class DaggerBreadShop implements BreadShop { private Provider<Bread> provideBreadProvider; private DaggerBreadShop(Builder builder) { assert builder != null; initialize(builder); } private void initialize(final Builder builder) { this.provideBreadProvider = BreadModule_ProvideBreadFactory.create(builder.breadModule); } @Override public Bread bread() { return provideBreadProvider.get(); } public static final class Builder { private BreadModule breadModule; private Builder() { }

@Generated("dagger.internal.codegen.ComponentProcessor")public final class DaggerBreadShop implements BreadShop { private Provider<Bread> provideBreadProvider; private DaggerBreadShop(Builder builder) { assert builder != null; initialize(builder); } private void initialize(final Builder builder) { this.provideBreadProvider = BreadModule_ProvideBreadFactory.create(builder.breadModule); } @Override public Bread bread() { return provideBreadProvider.get(); } public static final class Builder { private BreadModule breadModule; private Builder() { }

@Generated("dagger.internal.codegen.ComponentProcessor") public final class BreadModule_ProvideBreadFactory implements Factory<Bread> { private final BreadModule module; public BreadModule_ProvideBreadFactory(BreadModule module) { assert module != null; this.module = module; } @Override public Bread get() { Bread provided = module.provideBread(); if (provided == null) { throw new NullPointerException("Cannot return null from a non-@Nullable @Provides method"); } return provided; } public static Factory<Bread> create(BreadModule module) { return new BreadModule_ProvideBreadFactory(module); } }

@Generated("dagger.internal.codegen.ComponentProcessor")public final class BreadModule_ProvideBreadFactory implements Factory<Bread> { private final BreadModule module; public BreadModule_ProvideBreadFactory(BreadModule module) { assert module != null; this.module = module; } @Override public Bread get() { Bread provided = module.provideBread(); if (provided == null) { throw new NullPointerException("Cannot return null from a non-@Nullable @Provides method"); } return provided; } public static Factory<Bread> create(BreadModule module) { return new BreadModule_ProvideBreadFactory(module); }}

DaggerBreadShop::bread()


BreadModule_ProvideBreadFactory::get()



BreadModule::provideBread()




new Chokokorone()!!

Case 2 Singleton


@Modulepublic class BreadModule { @Provides Bread provideBread() { return new Chokokorone(); } }

Before

@Singleton @Component(modules = BreadModule.class) interface BreadShop { Bread bread(); }

@Modulepublic class BreadModule { @Singleton @Provides Bread provideBread() { return new Chokokorone(); } }

After

@Singleton @Component(modules = BreadModule.class)interface BreadShop { Bread bread();}

@Modulepublic class BreadModule { @Singleton @Provides Bread provideBread() { return new Chokokorone(); }}

After

private void initialize(final Builder builder) { this.provideBreadProvider = BreadModule_ProvideBreadFactory.create(builder.breadModule); }

Before

private void initialize(final Builder builder) { this.provideBreadProvider = ScopedProvider.create( BreadModule_ProvideBreadFactory.create(builder.breadModule) ); }

After

public final class ScopedProvider<T> implements Provider<T> { : @Override public T get() { // double-check idiom from EJ2: Item 71 Object result = instance; if (result == UNINITIALIZED) { synchronized (this) { result = instance; if (result == UNINITIALIZED) { instance = result = factory.get(); } } } return (T) result; } : }


ScopedProvider::get()




new Chokokorone()!! (1度取得したら使い回す)

Case 3 Inject


Before


Bread bread = shop.bread();

Before

@Component(modules = BreadModule.class) interface BreadShop { void bread(Lunch lunch); }

After

public class Lunch { @Inject Bread bread; }

@Component(modules = BreadModule.class)interface BreadShop { void bread(Lunch lunch); }

After

public class Lunch { @Inject Bread bread; }

BreadShop shop = DaggerBreadShop .builder() .breadModule(new BreadModule()) .build(); Lunch lunch = new Lunch(); shop.bread(lunch); // lunch.bread is Chokokorone

After

BreadShop shop = DaggerBreadShop .builder() .breadModule(new BreadModule()) .build();Lunch lunch = new Lunch(); shop.bread(lunch); // lunch.bread is Chokokorone

After



• Lunch_MembersInjector

private void initialize(final Builder builder) { this.provideBreadProvider = BreadModule_ProvideBreadFactory.create(builder.breadModule); } @Override public Bread bread() { return provideBreadProvider.get(); }

Before

private void initialize(final Builder builder) { this.provideBreadProvider = BreadModule_ProvideBreadFactory.create(builder.breadModule); this.lunchMembersInjector = Lunch_MembersInjector.create(provideBreadProvider); } @Override public void bread(Lunch lunch) { lunchMembersInjector.injectMembers(lunch); }

After

@Generated("dagger.internal.codegen.ComponentProcessor") public final class Lunch_MembersInjector implements MembersInjector<Lunch> { private final Provider<Bread> breadProvider; public Lunch_MembersInjector(Provider<Bread> breadProvider) { assert breadProvider != null; this.breadProvider = breadProvider; } @Override public void injectMembers(Lunch instance) { if (instance == null) { throw new NullPointerException("Cannot inject members into a null reference"); } instance.bread = breadProvider.get(); } public static MembersInjector<Lunch> create(Provider<Bread> breadProvider) { return new Lunch_MembersInjector(breadProvider); } }

@Generated("dagger.internal.codegen.ComponentProcessor")public final class Lunch_MembersInjector implements MembersInjector<Lunch> { private final Provider<Bread> breadProvider; public Lunch_MembersInjector(Provider<Bread> breadProvider) { assert breadProvider != null; this.breadProvider = breadProvider; } @Override public void injectMembers(Lunch instance) { if (instance == null) { throw new NullPointerException("Cannot inject members into a null reference"); } instance.bread = breadProvider.get(); } public static MembersInjector<Lunch> create(Provider<Bread> breadProvider) { return new Lunch_MembersInjector(breadProvider); }}

DaggerBreadShop::bread(Lunch launch)


Lunch_MembersInjector::injectMembers(Lunch launch)



lunch = BreadModule_ProvideBreadFactory::get()




lunch = BreadModule::provideBread()




lunch = BreadModule::provideBread()

lunch = new Chokokorone()!!

まとめ

Dagger2は怖くない

読むと怖くないdagger2

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