startActivity桌面启动应用

android12-release

1. Launcher点击应用图标

packages/apps/Launcher3/src/com/android/launcher3/touch/ItemClickHandler.java
packages/apps/Launcher3/src/com/android/launcher3/Launcher.java
packages/apps/Launcher3/src/com/android/launcher3/BaseDraggingActivity.java
packages/apps/Launcher3/src/com/android/launcher3/BaseActivity.java

onClickAppShortcut -> startAppShortcutOrInfoActivity -> launcher.startActivitySafely -> startActivity()最后调用到Activity.java中。

其中intent包含信息：
action = “android.intent.action.MAIN”
category=“android.intent.category.LAUNCHER”
cmp=“[包名]/.MainActivity”

intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); // 配合android:taskAffinity，默认为包名，冷启动应用时Activity在新的任务栈中启动

<activity android:name=".MainActivity"  android:label="@string/app_name">  <intent-filter>  <action android:name="android.intent.action.MAIN" />  <category android:name="android.intent.category.LAUNCHER" />  </intent-filter>
</activity>

2. 桌面Activity – Instrumentation – AMS/ATMS

  • mParent 应用首次启动所以mParent为空。
  • mMainThread.getApplicationThread() 获取ApplicationThread成员变量，是一个Binder对象
  • mToken Activity类的成员变量，它是一个Binder对象的远程接口
  • ActivityTaskManager.getService() 获取Context.ACTIVITY_TASK_SERVICE 即是 ActivityTaskManagerService
  • Instrumentation.java 用来监控应用程序和系统的交互
  • checkStartActivityResult(result, intent); 检查是否启动成功

startActivity() -> startActivityForResult -> mInstrumentation.execStartActivity -> ActivityTaskManager.getService().startActivity

frameworks/base/core/java/android/app/Activity.java
frameworks/base/core/java/android/app/Instrumentation.java

public void startActivityForResult(@RequiresPermission Intent intent, int requestCode,@Nullable Bundle options) {if (mParent == null) {options = transferSpringboardActivityOptions(options);Instrumentation.ActivityResult ar =mInstrumentation.execStartActivity(this, mMainThread.getApplicationThread(), mToken, this,intent, requestCode, options);// ... ...} else {// ... ...}}

    public ActivityResult execStartActivity(Context who, IBinder contextThread, IBinder token, Activity target,Intent intent, int requestCode, Bundle options) {// ... ...try {intent.migrateExtraStreamToClipData(who);intent.prepareToLeaveProcess(who);int result = ActivityTaskManager.getService().startActivity(whoThread,who.getOpPackageName(), who.getAttributionTag(), intent,intent.resolveTypeIfNeeded(who.getContentResolver()), token,target != null ? target.mEmbeddedID : null, requestCode, 0, null, options);checkStartActivityResult(result, intent);} catch (RemoteException e) {throw new RuntimeException("Failure from system", e);}return null;}

2.1 ActivityTaskManager.getService()

  • IActivityTaskManagerSingleton.get()单例模式，Android 中 java 单例模板frameworks/base/core/java/android/util/Singleton.java，查看单例模式(Singleton) 2
  • 使用Binder IPC获取查看Binder系列3-framework层
  • Context.ACTIVITY_TASK_SERVICE AMS服务启动时注册到binder，ActivityManagerService启动-android12

3. Binder IPC调用到 ActivityTaskManagerService

frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
frameworks/base/services/core/java/com/android/server/wm/ActivityStartController.java
frameworks/base/services/core/java/com/android/server/wm/ActivityStarter.java

ActivityTaskManager.getService().startActivity -> startActivityAsUser() -> getActivityStartController().obtainStarter ........ execute() -> executeRequest(mRequest) -> startActivityUnchecked() -> startActivityInner()

  • obtainStarter(intent, "startActivityAsUser")工厂模式mFactory.obtain().setIntent(intent).setReason(reason)获取ActivityStarter
  • executeRequest(mRequest)这里输出START u日志，一般定制都会加上pid打印
  • ActivityRecord r,sourceRecord信息
  • startActivityInner()该方法有许多参数处理，如setInitialState\computeLaunchingTaskFlags\computeSourceStack\mIntent.setFlags(mLaunchFlags)\computeLaunchParams
  • startActivityInner() 这里wm_create_task、wm_create_activity
if (newTask) {EventLogTags.writeWmCreateTask(mStartActivity.mUserId,mStartActivity.getTask().mTaskId);}mStartActivity.logStartActivity(EventLogTags.WM_CREATE_ACTIVITY, mStartActivity.getTask());
  • mDoResume移到栈顶显示resumeFocusedTasksTopActivities

3.1 先startPausingLocked

mRootWindowContainer.resumeFocusedTasksTopActivities -> resumeTopActivityUncheckedLocked -> resumeTopActivityInnerLocked -> 先startPausingLocked后mTaskSupervisor.startSpecificActivity(next, true, true)

next.attachedToProcess()此时由于第一次（冷启动）为false，主要在Task.java操作resumeTopActivityInnerLocked()

  • 此时当前mResumedActivity != null，即为桌面Launcher，先startPausingLocked() 执行Pausing过程，并输出日志wm_pause_activity
if (mResumedActivity != null) {ProtoLog.d(WM_DEBUG_STATES, "resumeTopActivityLocked: Pausing %s", mResumedActivity);pausing |= startPausingLocked(false /* uiSleeping */, next,"resumeTopActivityInnerLocked");
}

  • prev = mResumedActivity、mPausingActivity = prev赋值mPausingActivity，并设置状态prev.setState(PAUSING, "startPausingLocked")

  • EventLogTags.writeWmPauseActivity() Event日志

  • mAtmService.getLifecycleManager().scheduleTransaction()执行PauseActivityItem，通过ActivityThread、Instrumentation.callActivityOnPause()通知到Activity onPause()，并输出wm_on_paused_called（Android P Basic lifecycle transaction containers --设计模式体现之策略模式）

  • completePauseLocked(false, resuming) pause完成，并设置状态prev.setState(PAUSED, "completePausedLocked");

frameworks/base/services/core/java/com/android/server/wm/Task.java

final boolean startPausingLocked(boolean userLeaving, boolean uiSleeping,ActivityRecord resuming, String reason) {// ... ...ActivityRecord prev = mResumedActivity;// ... ...ProtoLog.v(WM_DEBUG_STATES, "Moving to PAUSING: %s", prev);mPausingActivity = prev;mLastPausedActivity = prev;if (prev.isNoHistory() && !mTaskSupervisor.mNoHistoryActivities.contains(prev)) {mTaskSupervisor.mNoHistoryActivities.add(prev);}prev.setState(PAUSING, "startPausingLocked");prev.getTask().touchActiveTime();// ... ...boolean didAutoPip = false;if (prev.attachedToProcess()) {if (shouldAutoPip) {// ... ...} else {ProtoLog.v(WM_DEBUG_STATES, "Enqueueing pending pause: %s", prev);try {EventLogTags.writeWmPauseActivity(prev.mUserId, System.identityHashCode(prev),prev.shortComponentName, "userLeaving=" + userLeaving, reason);mAtmService.getLifecycleManager().scheduleTransaction(prev.app.getThread(),prev.appToken, PauseActivityItem.obtain(prev.finishing, userLeaving,prev.configChangeFlags, pauseImmediately));} catch (Exception e) {// ... ...}}} else {// ... ...}// ... ...// ... ...if (pauseImmediately) {// If the caller said they don't want to wait for the pause, then complete// the pause now.completePauseLocked(false, resuming);return false;}// ... ...}
  • 先走这里mTaskSupervisor.startSpecificActivity，执行realStartActivityLocked()；没有启动执行mService.startProcessAsync()

3.2 startSpecificActivity启动：AMS/ATMS -- Instrumentation -- 应用Activity

  • WindowProcessController wpc第一次启动获取到的是null；mService.startProcessAsync()先fork应用进程

frameworks/base/services/core/java/com/android/server/wm/ActivityTaskSupervisor.java

void startSpecificActivity(ActivityRecord r, boolean andResume, boolean checkConfig) {// Is this activity's application already running?final WindowProcessController wpc =mService.getProcessController(r.processName, r.info.applicationInfo.uid);boolean knownToBeDead = false;if (wpc != null && wpc.hasThread()) {try {realStartActivityLocked(r, wpc, andResume, checkConfig);return;} catch (RemoteException e) {Slog.w(TAG, "Exception when starting activity "+ r.intent.getComponent().flattenToShortString(), e);}// If a dead object exception was thrown -- fall through to// restart the application.knownToBeDead = true;}r.notifyUnknownVisibilityLaunchedForKeyguardTransition();final boolean isTop = andResume && r.isTopRunningActivity();mService.startProcessAsync(r, knownToBeDead, isTop, isTop ? "top-activity" : "activity");
}

3.2.1 启动ActivityThread(内部成员ApplicationThread)

  • startProcessAsync通过ATMS/AMS走到ProcessList.java中startProcess()调用Process.start，通过ZYGOTE_PROCESS.start fork生成进程，最后执行到 ActivityThread.main() 方法回调AMS.attachApplication
    public static void main(String[] args) {// ... ...Looper.prepareMainLooper();// ... ...ActivityThread thread = new ActivityThread();thread.attach(false, startSeq);// ... ...Looper.loop();throw new RuntimeException("Main thread loop unexpectedly exited");}

相关查看ActivityThread应用进程

  • ProcessList.java中handleProcessStartedLocked输出am_proc_start、AMS.attachApplication输出am_proc_bound
EventLog.writeEvent(EventLogTags.AM_PROC_START,UserHandle.getUserId(app.getStartUid()), pid, app.getStartUid(),app.processName, app.getHostingRecord().getType(),app.getHostingRecord().getName() != null ? app.getHostingRecord().getName() : "");EventLogTags.writeAmProcBound(app.userId, pid, app.processName);
  • 几经attachApplication:AMS.attachApplication -> ATMS.attachApplication -> RootWindowContainer.attachApplication(wpc) -> mTaskSupervisor.realStartActivityLocked()；最终还是调用到realStartActivityLocked
  • AMS.attachApplication中thread.bindApplication()创建Instrumentation、app = data.info.makeApplication(data.restrictedBackupMode, null)，并通过Instrumentation通知到Application：
mInstrumentation.onCreate(data.instrumentationArgs);
mInstrumentation.callApplicationOnCreate(app);

3.2.2 realStartActivityLocked()真正启动APP

ActivityThread.main() -> AMS.attachApplication -> ATMS.attachApplication -> RootWindowContainer.attachApplication(wpc) / startActivityForAttachedApplicationIfNeeded -> mTaskSupervisor.realStartActivityLocked()

  • Event日志wm_restart_activity
EventLogTags.writeWmRestartActivity(r.mUserId, System.identityHashCode(r),task.mTaskId, r.shortComponentName);
  • mService.getLifecycleManager().scheduleTransaction(clientTransaction);通知到Activity Resumed: wm_on_resume_called
mInstrumentation.callActivityOnResume(this);
EventLogTags.writeWmOnResumeCalled(mIdent, getComponentName().getClassName(), reason);
  • 与上面pause不同的是添加了LaunchActivityItem

frameworks/base/core/java/android/app/servertransaction/TransactionExecutor.java
(Android P Basic lifecycle transaction containers--设计模式体现之策略模式)

  • TransactionExecutor先执行executeCallbacks即执行LaunchActivityItem，所以在Resuemed之前处理handleLaunchActivity()：
  1. 初始化activity = mInstrumentation.newActivity()
  2. activity.attach() 处理WMS相关信息
  3. mInstrumentation.callActivityOnCreate()通知onCreate，设置ActivityClientRecord r.setState(ON_CREATE);
  4. executeLifecycleState(transaction)在ON_CREATE和ON_RESUME之间添加ON_START流程: mHelper.getLifecyclePath(start, finish, excludeLastState)

frameworks/base/core/java/android/app/servertransaction/TransactionExecutor.java

    public void execute(ClientTransaction transaction) {// ... ...if (DEBUG_RESOLVER) Slog.d(TAG, transactionToString(transaction, mTransactionHandler));executeCallbacks(transaction);executeLifecycleState(transaction);mPendingActions.clear();if (DEBUG_RESOLVER) Slog.d(TAG, tId(transaction) + "End resolving transaction");}

frameworks/base/core/java/android/app/ActivityThread.java

    public Activity handleLaunchActivity(ActivityClientRecord r,PendingTransactionActions pendingActions, Intent customIntent) {// ... ...// Make sure we are running with the most recent config.mConfigurationController.handleConfigurationChanged(null, null);if (localLOGV) Slog.v(TAG, "Handling launch of " + r);// Initialize before creating the activityif (ThreadedRenderer.sRendererEnabled&& (r.activityInfo.flags & ActivityInfo.FLAG_HARDWARE_ACCELERATED) != 0) {HardwareRenderer.preload();}WindowManagerGlobal.initialize();// Hint the GraphicsEnvironment that an activity is launching on the process.GraphicsEnvironment.hintActivityLaunch();final Activity a = performLaunchActivity(r, customIntent);// ... ...}

4. 时序图

待续~~~ 道阻且长

Log关键字：
ActivityTaskManager: START u|ActivityTaskManager: Displayed
wm_create_activity|wm_set_resumed_activity|wm_resume_activity|wm_on_resume_called|wm_activity_launch_time

06-13 23:14:02.056 1000 1787 10268 I wm_create_task: [0,109]
06-13 23:14:02.056 1000 1787 10268 I wm_create_activity: [0,103558740,109,com.tencent.mobileqq/.activity.SplashActivity,android.intent.action.MAIN,NULL,NULL,270532608]
06-13 23:14:02.059 1000 1787 10268 I wm_pause_activity: [0,3858326,com.miui.home/.launcher.Launcher,userLeaving=true]
06-13 23:14:02.067 10083 22061 22061 I wm_on_paused_called: [0,com.miui.home.launcher.Launcher,performPause,1]

06-13 23:14:02.114 1000 1787 3359 I wm_restart_activity: [0,103558740,109,com.tencent.mobileqq/.activity.SplashActivity]
06-13 23:14:02.117 1000 1787 3359 I wm_set_resumed_activity: [0,com.tencent.mobileqq/.activity.SplashActivity,minimalResumeActivityLocked]
06-13 23:14:02.876 10264 26092 26092 I wm_on_create_called: [0,com.tencent.mobileqq.activity.SplashActivity,performCreate,105]
06-13 23:14:02.878 10264 26092 26092 I wm_on_start_called: [0,com.tencent.mobileqq.activity.SplashActivity,handleStartActivity,1]
06-13 23:14:02.885 10264 26092 26092 I wm_on_resume_called: [0,com.tencent.mobileqq.activity.SplashActivity,RESUME_ACTIVITY,7]
06-13 23:14:02.899 10264 26092 26092 I wm_on_top_resumed_gained_called: [103558740,com.tencent.mobileqq.activity.SplashActivity,topStateChangedWhenResumed]
06-13 23:14:02.988 1000 1787 1839 I wm_activity_launch_time: [0,103558740,com.tencent.mobileqq/.activity.SplashActivity,954]

相关文章：

Android应用程序启动过程源代码分析
Android应用程序内部启动Activity过程（startActivity）的源代码分析
startActivity启动过程分析
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