Application通过ActivityLifecycleCallbacks使用接口提供了一套回调方法，用于让开发者对Activity的生命周期事件进行集中处理。 ActivityLifecycleCallbacks接口回调可以简化监测Activity的生命周期事件，在一个类中作统一处理。 ActivityLifecycleCallbacks使用要求API 14+ （Android 4.0+）。
使用方法
重写Application的onCreate()方法，或在Application的无参构造方法内，调用Application.registerActivityLifecycleCallbacks()方法 ，并实现ActivityLifecycleCallbacks接口。
public class BaseApplication extends Application {
public void onCreate() {
super.onCreate();
this.registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {
@Override
public void onActivityStopped(Activity activity) {
Log.e("====", activity+"onActivityStopped");
}
@Override
public void onActivityStarted(Activity activity) {
Log.e("====", activity+"onActivityStarted");
}
@Override
public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
Log.e("====", activity + "onActivitySaveInstanceState");
}
@Override
public void onActivityResumed(Activity activity) {
Log.e("====", activity + "onActivityResumed");
}
@Override
public void onActivityPaused(Activity activity) {
Log.e("====", activity + "onActivityPaused");
}
@Override
public void onActivityDestroyed(Activity activity) {
Log.e("====", activity + "onActivityDestroyed");
}
@Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
Log.e("====", activity + "onActivityCreated");
}
});
};
}
为了测试，再新建两个activity：MainActivity和SecondActivity，点击MainActivity里面的按钮可以跳转到SecondActivity。 MainActivity代码如下：
public class MainActivity extends ActionBarActivity {
private Button btn = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn = (Button) findViewById(R.id.btn);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivity.this,SecondActivity.class);
startActivity(i);
}
});
Log.e("====", "MainActivity onCreate");
}
@Override
protected void onResume() {
super.onResume();
Log.e("====", "MainActivity onResume");
}
@Override
protected void onPause() {
super.onPause();
Log.e("====", "MainActivity onPause");
}
@Override
protected void onStart() {
super.onStart();
Log.e("====", "MainActivity onStart");
}
}
SecondActivity代码类似，不再贴出来。运行app，输出如下
11-25 16:45:24.043 2829-2829/com.mxn.soul.demo E/====: com.mxn.soul.demo.MainActivity@2300e06conActivityCreated
11-25 16:45:24.179 2829-2829/com.mxn.soul.demo E/====: MainActivity onCreate
11-25 16:45:24.238 2829-2829/com.mxn.soul.demo E/====: com.mxn.soul.demo.MainActivity@2300e06conActivityStarted
11-25 16:45:24.240 2829-2829/com.mxn.soul.demo E/====: MainActivity onStart
11-25 16:45:24.242 2829-2829/com.mxn.soul.demo E/====: com.mxn.soul.demo.MainActivity@2300e06conActivityResumed
11-25 16:45:24.242 2829-2829/com.mxn.soul.demo E/====: MainActivity onResume
11-25 16:45:36.768 2829-2829/com.mxn.soul.demo E/====: com.mxn.soul.demo.MainActivity@2300e06conActivityPaused
11-25 16:45:36.768 2829-2829/com.mxn.soul.demo E/====: MainActivity onPause
11-25 16:45:36.820 2829-2829/com.mxn.soul.demo E/====: com.mxn.soul.demo.SecondActivity@13adc62aonActivityCreated
11-25 16:45:36.856 2829-2829/com.mxn.soul.demo E/====: SecondActivity onCreate
11-25 16:45:36.858 2829-2829/com.mxn.soul.demo E/====: com.mxn.soul.demo.SecondActivity@13adc62aonActivityStarted
11-25 16:45:36.858 2829-2829/com.mxn.soul.demo E/====: SecondActivity onStart
11-25 16:45:36.859 2829-2829/com.mxn.soul.demo E/====: com.mxn.soul.demo.SecondActivity@13adc62aonActivityResumed
11-25 16:45:36.859 2829-2829/com.mxn.soul.demo E/====: SecondActivity onResume
11-25 16:45:37.321 2829-2829/com.mxn.soul.demo E/====: com.mxn.soul.demo.MainActivity@2300e06conActivitySaveInstanceState
11-25 16:45:37.321 2829-2829/com.mxn.soul.demo E/====: com.mxn.soul.demo.MainActivity@2300e06conActivityStopped
可以看到ActivityLifecycleCallbacks的回调在activity生命周期方法之前，这是因为我的log信息写在super之后：
@Override
protected void onResume() {
super.onResume();
Log.e("====", "MainActivity onResume");
}
如果把log写在super之前，那么结果就是相反的了。
@Override
protected void onResume() {
Log.e("====", "MainActivity onResume");
super.onResume();
}
输出如下：
11-25 17:28:15.652 27469-27469/? E/====: MainActivity onResume
11-25 17:28:15.653 27469-27469/? E/====: com.mxn.soul.demo.MainActivity@2300e06conActivityResumed
用ActivityLifecycleCallbacks管理Activity堆栈
可以用ActivityLifecycleCallbacks和LinkedList来管理所有的Activity，可以实现完全退出一个应用。
public class BaseApplication extends Application implements Application.ActivityLifecycleCallbacks {
private LinkedList<ActivityInfo> mExistedActivitys = new LinkedList<>();
private static BaseApplication mInstance;
public static synchronized BaseApplication getInstance() {
return mInstance;
}
public void onCreate() {
super.onCreate();
registerActivityLifecycleCallbacks(this);
mInstance = this;
}
@Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
if (null != mExistedActivitys && null != activity) {
// 把新的 activity 添加到最前面，和系统的 activity 堆栈保持一致
mExistedActivitys.offerFirst(new ActivityInfo(activity,ActivityInfo.STATE_CREATE));
}
}
@Override
public void onActivityStarted(Activity activity) {
}
@Override
public void onActivityResumed(Activity activity) {
}
@Override
public void onActivityPaused(Activity activity) {
}
@Override
public void onActivityStopped(Activity activity) {
}
@Override
public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
}
@Override
public void onActivityDestroyed(Activity activity) {
if (null != mExistedActivitys && null != activity) {
ActivityInfo info = findActivityInfo(activity);
if (null != info) {
mExistedActivitys.remove(info);
}
}
}
class ActivityInfo {
private final static int STATE_NONE = 0;
private final static int STATE_CREATE = 1;
Activity mActivity;
int mState;
ActivityInfo() {
mActivity = null;
mState = STATE_NONE;
}
ActivityInfo(Activity activity, int state) {
mActivity = activity;
mState = state;
}
}
public void exitAllActivity() {
if (null != mExistedActivitys) {
// 先暂停监听（省得同时在2个地方操作列表）
unregisterActivityLifecycleCallbacks( this );
// 弹出的时候从头开始弹，和系统的 activity 堆栈保持一致
for (ActivityInfo info : mExistedActivitys) {
if (null == info || null == info.mActivity) {
continue;
}
try {
info.mActivity.finish();
} catch (Exception e) {
e.printStackTrace();
}
}
mExistedActivitys.clear();
// 退出完之后再添加监听
registerActivityLifecycleCallbacks( this );
}
}
private ActivityInfo findActivityInfo(Activity activity) {
if (null == activity || null == mExistedActivitys) {
return null;
}
for (ActivityInfo info : mExistedActivitys) {
if (null == info) {
continue;
}
if (activity.equals(info.mActivity)) {
return info;
}
}
return null;
}
}
结束程序时调用：
BaseApplication.getInstance().exitAllActivity() ;
但是如果应用内有多个进程，每创建一个进程就会跑一次Application的onCreate方法，每个进程内存都是独立的， 所以通过这种方式无法实现将应用的Activity放在同一个LinkedList中，不能实现完全退出一个应用。
