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 getModules() {
           return Arrays.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();
       }
    
    }

  6. 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。

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