Dagger高级用法：任性inject

Dagger高级用法：任性inject

用了注入之后，就有这么一个需求：随时随地任性inject :), 对！我们将提供inject的注入，这样我们就可以实现任性inject！

开启我们的任性之旅吧

1. 定义Injector接口

   public interface Injector {
      public void inject(Object object);
   }

   ​

2. Application中实现Injector接口

   public class App extends Application implements Injector{
   
      private ObjectGraph applicationGraph;
   
      @Override
      public void onCreate() {
          super.onCreate();
          applicationGraph = ObjectGraph.create(getModules().toArray());
          applicationGraph.inject(this);
      }
   
      protected List<Object> getModules() {
          return Arrays.<Object>asList(new AppModule(this));
      }
   
      @Override
      public void inject(Object object) {
          applicationGraph.inject(object);
      }
   
   }

   ​

3. 创建InjectorModule

   @Module(
          library = true
   )
   public class InjectorModule {
   
      private App app;
   
      public InjectorModule(App app) {
          this.app = app;
      }
   
      @Provides@Singleton
      public Injector providerInjector() {
          return app;
      }
   }

   ​

4. 关键的一步：借助构造方法的参数随时随地获取Injector,并将含有注入的对象注入；

   @Singleton
   public class SingletonModule {
   
      private Injector injector;
   
      @Inject
      public SingletonModule(Injector injector) {
          this.injector = injector;
      }
   
      public void doToast() {
          InjectHandler handler = new InjectHandler();
          injector.inject(handler);
          handler.sendEmptyMessage(1);
      } 
   }

   public class InjectHandler extends Handler{
   
      @Inject
      Toast toast;
   
      @Override
      public void handleMessage(Message msg) {
          super.handleMessage(msg);
          toast.setText("InjectHandler");
          toast.show();
      }
   }

   notice：在提供Toast的Provider的Module中加入injects = InjectHandler.class、在AppModule中includes = InjectorModule.class、在ObjectGraph.create中加入new InjectorModule(this)

   ​

5. 调用

   public class MainActivity extends AppCompatActivity {
   
      @Inject
      SingletonModule sToast;
   
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main2);
          ((App) getApplicationContext()).inject(this);
          sToast.doToast();
      }
   
   }

   ​

任性之旅已经结束，欢迎下次再来任性。

总结：

1. 任性并不是在任何地方，而是有一个前提条件需要@Singleton修饰Class， @Inject修饰构造方法，构造方法中就是一个获取Injector的机会，由此可见，任性只有一次机会；拿到Injector那就是任性的开始。
2. 继续任性的话只需要重复步骤4即可。