LifecycleObserver(Activity生命周期相关

如果某一个代码逻辑和Activity生命周期相关，但是又不想将逻辑代码写到Activity中，那么就可以使用LifecycleObserver，

首先实现LifecycleObserver接口并写出自己需要的生命周期相关方法，并通过@OnLifecycleEvent(Lifecycle.Event.ON_CREATE)注解来确定生命周期对应的方法

public class TestLifecycleObserver implements LifecycleObserver {
    private static final String TAG = TestLifecycleObserver.class.getCanonicalName();

    public TestLifecycleObserver() {
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_CREATE)
    public void onCreate(){
        Log.e(TAG, "onCreate: ");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_START)
    public void onStart(){
        Log.e(TAG, "onStart: ");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_RESUME)
    public void onResume(){
        Log.e(TAG, "onResume: ");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_PAUSE)
    public void onPause(){
        Log.e(TAG, "onPause: ");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_STOP)
    public void onStop(){
        Log.e(TAG, "onStop: ");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
    public void onDestroy(){
        Log.e(TAG, "onDestroy: ");
    }

然后在对应的Activity中注册TestLifecycleObserver

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        getLifecycle().addObserver(new TestLifecycleObserver());
    }

注意:Lifecycle.Event中并没有onRestart方法对应的常量