AndroidX-Jetpack-Lifecycle

当前版本：
compileSdkVersion 29
implementation 'androidx.appcompat:appcompat:1.2.0'

第一步：创建Activity继承AppCompatActivity类。

public class LifeCycleActivity extends AppCompatActivity {
 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_life_cycle);

    }
}

第二步：定义一个类MyLifeCycleObserver，实现LifecycleObserver接口。

在MyLifeCycleObserver中定义方法，加上@OnLifecycleEvent注解

import android.util.Log;

import androidx.lifecycle.Lifecycle;
import androidx.lifecycle.LifecycleObserver;
import androidx.lifecycle.OnLifecycleEvent;
public class MyLifeCycleObserver implements LifecycleObserver {
    private static final String TAG = MyLifeCycleObserver.class.getSimpleName();

    @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 onDestory() {
        Log.e(TAG, "onDestory");
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_ANY)
    public void onAny() {
        Log.e(TAG, "onAny");
    }

}

第三步：在Activity中，getLifecycle().addObserver(new MyLifeCycleObserver());

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.e(TAG, "onCreate    enable:"+enable());
        setContentView(R.layout.activity_life_cycle);
        getLifecycle().addObserver(new MyLifeCycleObserver());
    }

MyLifeCycleObserver 由创建到销毁，其生命周期方法的会被MyLifeCycleObserver观察到，并依次执行其生命周期相关联的方法。
运行结果如下

2020-11-19 10:11:34.793 20430-20430/com.example.jetpack E/LifeCycleActivity: onCreate
2020-11-19 10:11:34.815 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onCreate
2020-11-19 10:11:34.815 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny

2020-11-19 10:11:34.818 20430-20430/com.example.jetpack E/LifeCycleActivity: onStart
2020-11-19 10:11:34.818 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onStart
2020-11-19 10:11:34.818 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny

2020-11-19 10:11:34.818 20430-20430/com.example.jetpack E/LifeCycleActivity: onResume
2020-11-19 10:11:34.818 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onResume
2020-11-19 10:11:34.819 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny

2020-11-19 10:11:38.678 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onPause
2020-11-19 10:11:38.678 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny
2020-11-19 10:11:38.678 20430-20430/com.example.jetpack E/LifeCycleActivity: onPause

2020-11-19 10:11:39.278 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onStop
2020-11-19 10:11:39.278 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny
2020-11-19 10:11:39.278 20430-20430/com.example.jetpack E/LifeCycleActivity: onStop

2020-11-19 10:11:39.279 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onDestory
2020-11-19 10:11:39.279 20430-20430/com.example.jetpack E/MyLifeCycleObserver: onAny
2020-11-19 10:11:39.280 20430-20430/com.example.jetpack E/LifeCycleActivity: onDestroy

需要注意的是：

当activity生命周期方法触发时，会同时回调到这里
需要注意的是：
1.onCreate、onStart和onResume三个方法，会在对应的Activity方法执行完之后执行，
而onPause、onStop和onDestory 三个方法，会在对应的Activity方法之前执行。
2.onAny方法会在LifecycleObserver的每个生命周期方法执行之后调用。