使用Dagger2

说明

依赖注入

依赖库

Module

build.gradle

dependencies {
  compile 'com.google.dagger:dagger:2.0.2'
  //Required by Dagger2
  compile 'javax.annotation:javax.annotation-api:1.2'
  or
  compile 'org.glassfish:javax.annotation:10.0-b28' 

  apt 'com.google.dagger:dagger-compiler:2.0.2'
}

Project

build.gradle

dependencies {
    classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'    
}

构建依赖

@Module public class AppModule { 
   App mApplication; 
   public AppModule(Application application) {    
     mApplication = (App) application;    
  }    
  @Provides    
  App provideApplication() { return mApplication; }    
  @Provides   
  UserCache provideUserCache() { return new UserCacheWithFile(mApplication); }   
  @Provides   
  ECGCache provideECGCache(){ return new ECGCacheWithFile(mApplication); }  
}

构建注入器

@Component(modules = AppModule.class)
public interface AppComponent {    
    //exposed to sub graphs    
    //暴露给子图(设置 dependencies 的Component),使得子图可以继承使用    
    App app();   
    UserCache userCache();   
    ECGCache ecgCache();    
    ECGPrinter ecgPrint();
}

@Component(dependencies = AppComponent.class, modules = ActivityModule.class)
public interface ActivityComponent {    
    //不能使用基类,必须指定具体示例    
    //void inject(BaseActivity activity);    
    void inject(Test4Activity activity);    
    void inject(LoginActivity activity);    
    void inject(HistoryActivity activity);    
    void inject(EcgDetailActivity ecgDetailActivity);
}

ActivityComponent继承AppComponent的依赖,注入依赖时,会先到指定的Modules寻找,若modules没有找到需要的依赖关系,则根据@Inject标注声明寻找,若还是没有,则编译报错.

AppComponent的这段代码

    App app(); 
    UserCache userCache();
    ECGCache ecgCache(); 
    ECGPrinter ecgPrint();

是为继承了AppComponent 的 ActivityComponent 服务,把这些依赖关系暴露出来,让后者可以直接使用.

封装基类

• Application

public class App extends Application {    
    private AppComponent mAppComponent;    
    @Override    
    public void onCreate() {        
        super.onCreate();          
        initialize();    
    }      
    private void initialize() {       
        mAppComponent = DaggerAppComponent.builder().appModule(new AppModule(this)).build();    
    }    
    public AppComponent getAppComponent(){        
        return mAppComponent;   
    }
}

• Activity

public class BaseActivity extends AppCompatActivity {    
    ActivityComponent mActivityComponent;   
    protected ActivityComponent getActivityComponent() {        
        if (mActivityComponent == null) {            
              mActivityComponent = DaggerActivityComponent.builder().appComponent(getAppComponent())                    .activityModule(getActivityModule()).build();        
        }        
        return mActivityComponent;    
    }    
    protected ActivityModule getActivityModule(){
        return new ActivityModule();    
    }    
    protected AppComponent getAppComponent() {        
        return ((App) getApplication()).getAppComponent();    
    }
}

• Fragment

public class BaseFragment extends Fragment {    
    protected FragmentComponent getFragmentComponent() {       
        return DaggerFragmentComponent.builder().appComponent(getAppComponent()).build();    
    }    
    protected AppComponent getAppComponent() {        
        return ((App) getActivity().getApplication()).getAppComponent();    
    }
}

依赖注入

• Activity

public class LoginActivity extends BaseActivity implements LoginPresenter.MvpView {
    @Inject
    LoginPresenter loginPresenter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        //重要! 依赖注入,来自BaseActivity
        getActivityComponent().inject(this);

        loginPresenter.setView(this);
        loginPresenter.initialize();
    }
}

• Fragment

public class BlankFragment extends BaseFragment {
    @Inject
    ECGCache mECGCache;
    @Inject
    UserCache userCache;

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        //重要! 依赖注入,来自BaseFragment
        getFragmentComponent().inject(this);
    }
}

参考

• https://github.com/hitherejoe/Android-Boilerplate
• https://github.com/android10/Android-CleanArchitecture
• http://codethink.me/2015/08/06/dependency-injection-with-dagger-2/
• http://www.cnblogs.com/tiantianbyconan/p/5095426.html
• http://www.open-open.com/lib/view/open1438910855489.html
• http://www.jianshu.com/p/c2feb21064bb