Dagger2의 간단한 사용

문서 목록

1. 예비 지식

1.1 메모 개념

1.2 제어 반전과 의존 주입 개념

2. Dagger2의 사용

2.1 기본 사용 방법

api 'com.google.dagger:dagger:2.24'
annotationProcessor 'com.google.dagger:dagger-compiler:2.24'

//Tips.class       
import javax.inject.Inject;

public class Tips {

    @Inject
    public Tips() {
    }

    public String getTip() {
        return "        !";
    }
}

/**
* MainActivityComponent.class
*        ，(        )
*     ：    (    )+Component
*/
import dagger.Component;

@Component
public interface MainActivityComponent {
    void inject(MainActivity mainActivity);
}

/**
* MainActivity.class   
* 1 :@Inject         。
* 2 :    。
*/
@Inject//1
Tips tips;

@Override
protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_main);	
    DaggerMainActivityComponent.create().inject(this);//2
    tips.getTip();
}

2.2 @Module 및 @Provides

//GsonModule.class
import com.google.gson.Gson;

import dagger.Module;
import dagger.Provides;

@Module
public class GsonModule {
    @Provides
    public Gson provideGson(){
        return new Gson();
    }
}

//GsonModule.class
import com.virtual.learnrxjava.GsonModule;
import com.virtual.learnrxjava.MainActivity;

import dagger.Component;

@Component(modules = GsonModule.class)
public interface MainActivityComponent {
    void inject(MainActivity mainActivity);
}

//  SubClass.class     SuperClass.class
@Module
public class SubModule {
    @Provides
    public SuperClass getSubClass(){
        return new SubClass();
    }
}

2.3 @Named 및 @Qualifier

@Module
public class GsonModule {
    @Provides
    @Named("g1")
    public Gson provideGsonA(){
        return new Gson();
    }
    
    @Provides
    @Named("g2")
    public Gson provideGsonB(){
        return new Gson();
    }
}

//    
@Injetc
public showJson(@Named("g1") Gson gson){
    ...
}

//    
//myGson1.class
@Qualifier
@Retention(RUNTIME)
public @interface myGson1{
}

//myGson2.class
@Qualifier
@Retention(RUNTIME)
public @interface myGson2{
}

@Module
public class GsonModule {
    @Provides
    @myGson1
    public Gson provideGsonA(){
        return new Gson();
    }
    
    @Provides
    @myGson2
    public Gson provideGsonB(){
        return new Gson();
    }
}

@Injetc
public showJson(@myGson1 Gson gson){
    ...
}

2.4 @Singleton 및 @Scope

@Module
public class GsonModule {
    @Singleton
    @Provides
    public Gson provideGson(){
        return new Gson();
    }
}

@Singleton
@Component(modules = GsonModule.class)
public interface MainActivityComponent {
    void inject(MainActivity mainActivity);
}

//    
@Scope
@Retention(RUNTIME)
public @interface ApplicationScope{
}

@Module
public class GsonModule {
    @ApplicationScope
    @Provides
    public Gson provideGson(){
        return new Gson();
    }
}

@ApplicationScope
@Component(modules = GsonModule.class)
public interface MainActivityComponent {
    void inject(MainActivity mainActivity);
}

//  App  Application
import android.app.Application;
import android.content.Context;

public class App extends Application {
    ActivityComponent activityComponent;

    @Override
    public void onCreate() {
        super.onCreate();
        activityComponent=DaggerActivityComponent.builder().build();
    }
    
    public static App get(Context context){
        return (App)context.getApplicationContext();
    }
    
    ActivityComponent getActivityComponent(){
        return activityComponent;
    }
}

@ApplicationScope
@Component(modules = GsonModule.class)
public interface ActivityComponent {
    void inject(MainActivity activity);
    void inject(SecondActivity activity);
}

2.5 @Component의 dependencies

//  New.class
import javax.inject.Inject;

public class New {
    @Inject
    public New(){
    }

    public String msg(){
        return "Hello!";
    }
}

//  NewModule.class
import dagger.Module;
import dagger.Provides;

@Module
public class NewModule {
    @Provides
    public New providerNew(){
        return new New();
    }
}

//  NewComponent.class
import dagger.Component;

@Component(modules = NewModule.class)
public interface NewComponent {
    New getNew();
}

@Component(modules = GsonModule.class,dependencies = NewComponent.class)
public interface ActivityComponent {
    void inject(MainActivity activity);
    void inject(SecondActivity activity);
}

//  App.class  
 @Override
    public void onCreate() {
        super.onCreate();
        activityComponent=DaggerActivityComponent.builder().
            newComponent(DaggerNewComponent.create()).build();
    }

2.6 게으름 피우기

//    
@Inject
Lazy<Tips> tipsLazy;

...
    
    Tips tipsExample = tipsLazy.get()

3. 참고 자료