Android架构组件

简单介绍LiveData如何绑定在Activity和Fragment的生命周期，以及使用场景

一、类图

image

二、总结

通过绑定Android系统组件或者自定义，管理生命周期

使用注解、反射实现模板方法，监听生命周期

使用观察者模式，监听数据变化

三、使用场景

定义MVP框架模式中的P的生命周期，就非常方便，不需要在基类BasePresenter中定义很多生命周期函数

public class Presenter<T extends Presenter.View> {

    protected T view;

    @CallSuper
    public void onAttachView(T view) {
        this.view = view;
    }

    @CallSuper
    public void onDetachView() {
        view = null;
    }

    public interface View {
    }
}

public class ArcPresenter extends Presenter<ArcPresenterView> implements LifecycleObserver {

    private static final String TAG = ArcPresenter.class.getSimpleName();

    private final LifecycleOwner lifecycleOwner;

    public ArcPresenter(LifecycleOwner lifecycleOwner) {
        this.lifecycleOwner = lifecycleOwner;
    }

    private boolean isResume() {
        return lifecycleOwner.getLifecycle().getCurrentState().isAtLeast(Lifecycle.State.RESUMED);
    }

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

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

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

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

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

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

    @Override
    public void onAttachView(ArcPresenterView view) {
        super.onAttachView(view);
        Log.i(TAG, "onAttachView");
    }

    @Override
    public void onDetachView() {
        super.onDetachView();
        Log.i(TAG, "onDetachView");
    }
}

自定义有生命周期的组件