继续我们的源码解析,上一篇文章我们介绍了Activity的启动流程,一个典型的场景就是Activity a 启动了一个Activity b,他们的生命周期回调方法是:
onPause(a) –> onCreate(b) –> onStart(b) –> onResume(b) –> onStop(a)
而我们根据源码也验证了这样的生命周期调用序列,那么Activity的销毁流程呢?它的生命周期的调用顺序又是这样的呢?
这里我们我做一个简单的demo,让一个Activity a启动Activity b,然后在b中调用finish()方法,它们的生命周期执行顺序是:
onPause(b)
onRestart(a)
onStart(a)
onResume(a)
onStop(b)
onDestory(b)
好吧,根据我们测试的生命周期方法的回调过程开始对Activity销毁流程的分析,一般而言当我们需要销毁Activity的时候都会调用其自身的finish方法,所以我们的流程开始是以finish方法开始的。
一:请求销毁当前Activity
MyActivity.finish()
Activity.finish()
ActivityManagerNative.getDefault().finishActivity()
ActivityManagerService.finishActivity()
ActivityStack.requestFinishActivityLocked()
ActivityStack.finishActivityLocked()
ActivityStack.startPausingLocked()
首先我们在自己的Activity调用了finish方法,它实际上调用的是Activity的finish方法:
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public void finish() { finish( false ); } |
然后我们可以发现其调用了finish方法的重载方法,并且传递了一个参数值:
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private void finish( boolean finishTask) { if (mParent == null ) { int resultCode; Intent resultData; synchronized ( this ) { resultCode = mResultCode; resultData = mResultData; } if ( false ) Log.v(TAG, "Finishing self: token=" + mToken); try { if (resultData != null ) { resultData.prepareToLeaveProcess(); } if (ActivityManagerNative.getDefault() .finishActivity(mToken, resultCode, resultData, finishTask)) { mFinished = true ; } } catch (RemoteException e) { // Empty } } else { mParent.finishFromChild( this ); } } |
好吧,这个参数值似乎并没什么用。。。这里就不在讨论了,然后调用了ActivityManagerNative.getDefault().finishActivity方法,好吧,根据上一篇文章的介绍,我们知道了ActivityManagerNative是一个Binder对象,这里调用的方法最终会被ActivityManagerService执行,所以这了的finishActivity最终被执行的是ActivityManagerService.finishActivity方法,好吧,我们来看一下ActivityManagerService的finishActivity方法的执行逻辑。。。
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@Override public final boolean finishActivity(IBinder token, int resultCode, Intent resultData, boolean finishTask) { ... res = tr.stack.requestFinishActivityLocked(token, resultCode,resultData, "app-request" , true ); ... } |
这里我们可以发现,经过一系列逻辑判断之后,最终调用了ActivityStack的requestFinishActivityLocked方法,这里应该就是执行finish Activity的逻辑了。
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final boolean requestFinishActivityLocked(IBinder token, int resultCode, Intent resultData, String reason, boolean oomAdj) { ActivityRecord r = isInStackLocked(token); if (DEBUG_RESULTS || DEBUG_STATES) Slog.v(TAG_STATES, "Finishing activity token=" + token + " r=" + ", result=" + resultCode + ", data=" + resultData + ", reason=" + reason); if (r == null ) { return false ; } finishActivityLocked(r, resultCode, resultData, reason, oomAdj); return true ; } |
这个方法体里面又调用了finishActivityLocked方法,那我们继续看一下finishActivityLocked方法的实现:
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final boolean finishActivityLocked(ActivityRecord r, int resultCode, Intent resultData, String reason, boolean oomAdj) { ... startPausingLocked( false , false , false , false ); ... return false ; } |
好吧,在这里调用了startPausingLocked方法,看名字应该是开始要执行Activity的onPause方法请求了,然后我们看一下startPausingLocked方法的实现:
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final boolean startPausingLocked( boolean userLeaving, boolean uiSleeping, boolean resuming, boolean dontWait) { ... try { EventLog.writeEvent(EventLogTags.AM_PAUSE_ACTIVITY, prev.userId, System.identityHashCode(prev), prev.shortComponentName); mService.updateUsageStats(prev, false ); prev.app.thread.schedulePauseActivity(prev.appToken, prev.finishing, userLeaving, prev.configChangeFlags, dontWait); } catch (Exception e) { // Ignore exception, if process died other code will cleanup. Slog.w(TAG, "Exception thrown during pause" , e); mPausingActivity = null ; mLastPausedActivity = null ; mLastNoHistoryActivity = null ; } ... } |
这样从应用程序调用finish方法,ActivityManagerService接收请求并执行startPausingLocked方法。
二:执行当前Activity的onPause方法
IApplicationThread.schedulePauseActivity()
ActivityThread.schedulePauseActivity()
ActivityThread.sendMessage()
ActivityThread.H.sendMessage()
ActivityThread.H.handleMessage()
ActivityThread.handlePauseActivity()
ActivityThread.performPauseActivity()
Instrumentation.callActivityOnPause()
Activity.performPause()
Activity.onPause()
ActivityManagerNative.getDefault().activityPaused()
ActivityManagerService.activityPaused()
ActivityStack.activityPausedLocked()
ActivityStack.completePauseLocked()
在方法startPausingLocked中我们调用了:prev.app.thread.schedulePauseActivity这里实际上调用的是IApplicationThread的schedulePauseActivity方法,IApplicationThread也是一个Binder对象,它是ActivityThread中ApplicationThread的Binder client端,所以最终会调用的是ApplicationThread的schedulePauseActivity方法,好吧我们看一下ActivityThread的schedulePauseActivity方法的具体实现:
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public final void schedulePauseActivity(IBinder token, boolean finished, boolean userLeaving, int configChanges, boolean dontReport) { sendMessage( finished ? H.PAUSE_ACTIVITY_FINISHING : H.PAUSE_ACTIVITY, token, (userLeaving ? 1 : 0 ) | (dontReport ? 2 : 0 ), configChanges); } |
然后调用了ActivityThread的sendMessage方法:
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private void sendMessage( int what, Object obj, int arg1, int arg2) { sendMessage(what, obj, arg1, arg2, false ); } |
然后又回调了sendMessage的重载方法。。
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private void sendMessage( int what, Object obj, int arg1, int arg2, boolean async) { if (DEBUG_MESSAGES) Slog.v( TAG, "SCHEDULE " + what + " " + mH.codeToString(what) + ": " + arg1 + " / " + obj); Message msg = Message.obtain(); msg.what = what; msg.obj = obj; msg.arg1 = arg1; msg.arg2 = arg2; if (async) { msg.setAsynchronous( true ); } mH.sendMessage(msg); } |
最终调用mH发送异步消息,然后在mH的handleMessge方法中处理异步消息并调用handlePauseActivity方法:
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private void handlePauseActivity(IBinder token, boolean finished, boolean userLeaving, int configChanges, boolean dontReport) { ActivityClientRecord r = mActivities.get(token); if (r != null ) { //Slog.v(TAG, "userLeaving=" + userLeaving + " handling pause of " + r); if (userLeaving) { performUserLeavingActivity(r); } r.activity.mConfigChangeFlags |= configChanges; performPauseActivity(token, finished, r.isPreHoneycomb()); // Make sure any pending writes are now committed. if (r.isPreHoneycomb()) { QueuedWork.waitToFinish(); } // Tell the activity manager we have paused. if (!dontReport) { try { ActivityManagerNative.getDefault().activityPaused(token); } catch (RemoteException ex) { } } mSomeActivitiesChanged = true ; } } |
好吧,这里回调了performPauseActivity方法,上篇文章中我们已经分析过了这段代码:
performPauseActivity()
Instrumentation.callActivityOnPause()
Activity.performPause()
Activity.onPause()
这样我们就回调了第一个生命周期方法:onPause。。。
在handlePauseActivity方法中我们调用了ActivityManagerNative.getDefault().activityPaused(token)方法,好吧又是回调ActivityManagerService的方法,这样最终会调用ActivityManagerService的activityPaused方法:
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@Override public final void activityPaused(IBinder token) { final long origId = Binder.clearCallingIdentity(); synchronized ( this ) { ActivityStack stack = ActivityRecord.getStackLocked(token); if (stack != null ) { stack.activityPausedLocked(token, false ); } } Binder.restoreCallingIdentity(origId); } |
这样,我们继续看一下activityPausedLocked方法的实现:
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final void activityPausedLocked(IBinder token, boolean timeout) { ... completePauseLocked( true ); ... } |
里面又经过一系列的逻辑判断之后,开始执行completePauseLocked方法:
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private void completePauseLocked( boolean resumeNext) { ... mStackSupervisor.resumeTopActivitiesLocked(topStack, null , null ); ... } |
这样栈顶Activity的onPause操作就执行完成了,接下来就就是开始执行上一个Activity的onResume操作了。。。
三:执行上一个Activity的onResume操作
这样调用了ActivityStackSupervisor.resumeTopActivitiesLocked方法。。,又开始调用这个方法,通过上一篇文章的介绍,我们知道这个方法实际上是执行Activity的初始化,我们看一下其具体的调用过程:
ActivityStack.resumeTopActivityLocked()
ActivityStack.resumeTopInnerLocked()
IApplicationThread.scheduleResumeActivity()
ActivityThread.scheduleResumeActivity()
ActivityThread.sendMessage()
ActivityTherad.H.sendMessage()
ActivityThread.H.handleMessage()
ActivityThread.H.handleResumeMessage()
Activity.performResume()
Activity.performRestart()
Instrumentation.callActivityOnRestart()
Activity.onRestart()
Activity.performStart()
Instrumentation.callActivityOnStart()
Activity.onStart()
Instrumentation.callActivityOnResume()
Activity.onResume()
好吧,这个过程其实上一篇文章中已经做了介绍,这里不做过多的分析了,通过这样调用过程我们最终执行了当前栈顶Activity上一个Activity的onRestart方法,onStart方法,onResume方法等,下面我们将调用栈顶Activity的onStop方法,onDestory方法。
四:执行栈顶Activity的销毁操作
Looper.myQueue().addIdleHandler(new Idler())
ActivityManagerNative.getDefault().activityIdle()
ActivityManagerService.activityIdle()
ActivityStackSupervisor.activityIdleInternalLocked()
ActivityStack.destroyActivityLocked()
IApplicationThread.scheduleDestoryActivity()
ActivityThread.scheduleDestoryActivity()
ActivityThread.sendMessage()
ActivityThread.H.sendMessage()
ActivityThread.H.handleMessage()
ActivityThread.handleDestoryActivity()
ActivityThread.performDestoryActivity()
Activity.performStop()
Instrumentation.callActivityOnStop()
Activity.onStop()
Instrumentation.callActivityOnDestory()
Activity.performDestory()
Acitivity.onDestory()
ActivityManagerNative.getDefault().activityDestoryed()
ActivityManagerService.activityDestoryed()
ActivityStack.activityDestoryedLocked()
我们在ActivityThread.handleResumeActivity方法中调用了Looper.myQueue().addIdleHandler(new Idler()),下面看一下这个方法的实现:
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private class Idler implements MessageQueue.IdleHandler { @Override public final boolean queueIdle() { ActivityClientRecord a = mNewActivities; boolean stopProfiling = false ; if (mBoundApplication != null && mProfiler.profileFd != null && mProfiler.autoStopProfiler) { stopProfiling = true ; } if (a != null ) { mNewActivities = null ; IActivityManager am = ActivityManagerNative.getDefault(); ActivityClientRecord prev; do { if (localLOGV) Slog.v( TAG, "Reporting idle of " + a + " finished=" + (a.activity != null && a.activity.mFinished)); if (a.activity != null && !a.activity.mFinished) { try { am.activityIdle(a.token, a.createdConfig, stopProfiling); a.createdConfig = null ; } catch (RemoteException ex) { // Ignore } } prev = a; a = a.nextIdle; prev.nextIdle = null ; } while (a != null ); } if (stopProfiling) { mProfiler.stopProfiling(); } ensureJitEnabled(); return false ; } } |
内部有一个queueIdle的回调方法,当它被添加到MessageQueue之后就会回调该方法,我们可以发现在这个方法体中调用了ActivityManagerNative.getDefault.activityIdle方法,通过上一篇文章以及上面的讲解,我们应该知道这了最终调用的是ActivityManagerService.activityIdle方法,好吧,这里看一下activityIdle方法的具体实现:
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public final void activityIdle(IBinder token, Configuration config, boolean stopProfiling) { final long origId = Binder.clearCallingIdentity(); synchronized ( this ) { ActivityStack stack = ActivityRecord.getStackLocked(token); if (stack != null ) { ActivityRecord r = mStackSupervisor.activityIdleInternalLocked(token, false , config); if (stopProfiling) { if ((mProfileProc == r.app) && (mProfileFd != null )) { try { mProfileFd.close(); } catch (IOException e) { } clearProfilerLocked(); } } } } Binder.restoreCallingIdentity(origId); } |
可以发现这里又调用了ActivityStackSupervisor.activityIdleInternalLocked方法,然后我们看一下activityIdleInternalLocked方法的具体实现:
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final ActivityRecord activityIdleInternalLocked( final IBinder token, boolean fromTimeout, Configuration config) { .... stack.destroyActivityLocked(r, true , "finish-idle" ); .... } |
可以看到这里调用ActivityStack.destroyActivityLocked方法,可以看一下其具体实现:
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final boolean destroyActivityLocked(ActivityRecord r, boolean removeFromApp, String reason) { ... r.app.thread.scheduleDestroyActivity(r.appToken, r.finishing, r.configChangeFlags); ... } |
好吧,这里又开始执行IApplicationThread.scheduleDestoryActivity方法,上文已经做了说明这里最终调用的是ActivityThread.scheduleDestroyActivity方法,好吧,看一下ActivityThread.scheduleDestryActivity方法的实现:
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public final void scheduleDestroyActivity(IBinder token, boolean finishing, int configChanges) { sendMessage(H.DESTROY_ACTIVITY, token, finishing ? 1 : 0 , configChanges); } |
这里有开始执行sendMessage方法,通过一系列的调用sendMessage方法最终调用了handleDestroyActivity方法:
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private void handleDestroyActivity(IBinder token, boolean finishing, int configChanges, boolean getNonConfigInstance) { ActivityClientRecord r = performDestroyActivity(token, finishing, configChanges, getNonConfigInstance); if (r != null ) { cleanUpPendingRemoveWindows(r); WindowManager wm = r.activity.getWindowManager(); View v = r.activity.mDecor; if (v != null ) { if (r.activity.mVisibleFromServer) { mNumVisibleActivities--; } IBinder wtoken = v.getWindowToken(); if (r.activity.mWindowAdded) { if (r.onlyLocalRequest) { // Hold off on removing this until the new activity's // window is being added. r.mPendingRemoveWindow = v; r.mPendingRemoveWindowManager = wm; } else { wm.removeViewImmediate(v); } } if (wtoken != null && r.mPendingRemoveWindow == null ) { WindowManagerGlobal.getInstance().closeAll(wtoken, r.activity.getClass().getName(), "Activity" ); } r.activity.mDecor = null ; } if (r.mPendingRemoveWindow == null ) { // If we are delaying the removal of the activity window, then // we can't clean up all windows here. Note that we can't do // so later either, which means any windows that aren't closed // by the app will leak. Well we try to warning them a lot // about leaking windows, because that is a bug, so if they are // using this recreate facility then they get to live with leaks. WindowManagerGlobal.getInstance().closeAll(token, r.activity.getClass().getName(), "Activity" ); } // Mocked out contexts won't be participating in the normal // process lifecycle, but if we're running with a proper // ApplicationContext we need to have it tear down things // cleanly. Context c = r.activity.getBaseContext(); if (c instanceof ContextImpl) { ((ContextImpl) c).scheduleFinalCleanup( r.activity.getClass().getName(), "Activity" ); } } if (finishing) { try { ActivityManagerNative.getDefault().activityDestroyed(token); } catch (RemoteException ex) { // If the system process has died, it's game over for everyone. } } mSomeActivitiesChanged = true ; } |
可以看到这里调用了performDestroyActivity方法,用来执行Avtivity的onDestroy方法:
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private ActivityClientRecord performDestroyActivity(IBinder token, boolean finishing, int configChanges, boolean getNonConfigInstance) { ... r.activity.performStop(); ... mInstrumentation.callActivityOnDestroy(r.activity); ... } |
然后调用了Activity.performStop()方法,查看performStop方法:
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final void performStop() { ... mInstrumentation.callActivityOnStop( this ); ... } |
然后调用了Instrumentation.callActivityOnStop()方法:
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public void callActivityOnStop(Activity activity) { activity.onStop(); } |
好吧,终于调用了Activity的onStop方法。。。
我们继续看一下Instrumentation.callActivityOnDestroy()。。。。又是通过Instrumentation来调用Activity的onDestroy方法:
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public void callActivityOnDestroy(Activity activity) { ... activity.performDestroy(); ... } |
然后看一下Activity的performDestroy()方法的实现:
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final void performDestroy() { mDestroyed = true ; mWindow.destroy(); mFragments.dispatchDestroy(); onDestroy(); mFragments.doLoaderDestroy(); if (mVoiceInteractor != null ) { mVoiceInteractor.detachActivity(); } } |
O(∩_∩)O哈哈~,终于回调了Activity的onDestroy方法。。。。
总结:
Activity的销毁流程是从finish方法开始的
Activity销毁过程是:onPause –> onRestart –> onStart –> onResume –> onStop –> onDestroy
Activity的销毁流程是ActivityThread与ActivityManagerService相互配合销毁的
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://blog.csdn.net/qq_23547831/article/details/51232309