Activity.java
@Override
public void startActivity(Intent intent) {
this.startActivity(intent, null);
}
@Override
public void startActivity(Intent intent, @Nullable Bundle options) {
if (options != null) {
startActivityForResult(intent, -1, options);
} else {
// Note we want to go through this call for compatibility with
// applications that may have overridden the method.
startActivityForResult(intent, -1);
}
}
不管是调动哪个startActivity，最后都会调用startActivityForResult。
public void startActivityForResult(@RequiresPermission Intent intent, int requestCode) {
startActivityForResult(intent, requestCode, null);
}
public void startActivityForResult(@RequiresPermission Intent intent, int requestCode,
@Nullable Bundle options) {
if (mParent == null) {
options = transferSpringboardActivityOptions(options);
//重点在这一句
Instrumentation.ActivityResult ar = mInstrumentation.execStartActivity(
this, mMainThread.getApplicationThread(), mToken, this, intent, requestCode, options);
if (ar != null) {
mMainThread.sendActivityResult(
mToken, mEmbeddedID, requestCode, ar.getResultCode(),
ar.getResultData());
}
if (requestCode >= 0) {
// If this start is requesting a result, we can avoid making
// the activity visible until the result is received. Setting
// this code during onCreate(Bundle savedInstanceState) or onResume() will keep the
// activity hidden during this time, to avoid flickering.
// This can only be done when a result is requested because
// that guarantees we will get information back when the
// activity is finished, no matter what happens to it.
mStartedActivity = true;
}
cancelInputsAndStartExitTransition(options);
// TODO Consider clearing/flushing other event sources and events for child windows.
} else {
if (options != null) {
mParent.startActivityFromChild(this, intent, requestCode, options);
} else {
// Note we want to go through this method for compatibility with
// existing applications that may have overridden it.
mParent.startActivityFromChild(this, intent, requestCode);
}
}
}
Instrumentation.java
Instrumentation主要用来监控应用程序和系统的交互。
public ActivityResult execStartActivity(
Context who, IBinder contextThread, IBinder token, Activity target,
Intent intent, int requestCode, Bundle options) {
IApplicationThread whoThread = (IApplicationThread) contextThread;
Uri referrer = target != null ? target.onProvideReferrer() : null;
if (referrer != null) {
intent.putExtra(Intent.EXTRA_REFERRER, referrer);
}
***此处省略不少代码***
try {
intent.migrateExtraStreamToClipData(who);
intent.prepareToLeaveProcess(who);
//通过getService方法获取AMS的代理对象
int result = ActivityTaskManager.getService().startActivity(whoThread,
who.getBasePackageName(), 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;
}
ActivityManagerService.java
@Deprecated
@Override
public int startActivity(IApplicationThread caller, String callingPackage,
Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
int startFlags, ProfilerInfo profilerInfo, Bundle bOptions) {
return mActivityTaskManager.startActivity(caller, callingPackage, null, intent,
resolvedType, resultTo, resultWho, requestCode, startFlags, profilerInfo, bOptions);
}
ActivityTaskManagerService.java
@Override
public final int startActivity(IApplicationThread caller, String callingPackage,
String callingFeatureId, Intent intent, String resolvedType, IBinder resultTo,
String resultWho, int requestCode, int startFlags, ProfilerInfo profilerInfo,
Bundle bOptions) {
return startActivityAsUser(caller, callingPackage, callingFeatureId, intent, resolvedType,
resultTo, resultWho, requestCode, startFlags, profilerInfo, bOptions,
UserHandle.getCallingUserId());
}
@Override
public int startActivityAsUser(IApplicationThread caller, String callingPackage,
String callingFeatureId, Intent intent, String resolvedType, IBinder resultTo,
String resultWho, int requestCode, int startFlags, ProfilerInfo profilerInfo,
Bundle bOptions, int userId) {
return startActivityAsUser(caller, callingPackage, callingFeatureId, intent, resolvedType,
resultTo, resultWho, requestCode, startFlags, profilerInfo, bOptions, userId,
true /*validateIncomingUser*/);
}
private int startActivityAsUser(IApplicationThread caller, String callingPackage,
@Nullable String callingFeatureId, Intent intent, String resolvedType,
IBinder resultTo, String resultWho, int requestCode, int startFlags,
ProfilerInfo profilerInfo, Bundle bOptions, int userId, boolean validateIncomingUser) {
assertPackageMatchesCallingUid(callingPackage);
enforceNotIsolatedCaller("startActivityAsUser");
userId = getActivityStartController().checkTargetUser(userId, validateIncomingUser,
Binder.getCallingPid(), Binder.getCallingUid(), "startActivityAsUser");
// TODO: Switch to user app stacks here.
return getActivityStartController().obtainStarter(intent, "startActivityAsUser")
.setCaller(caller)
.setCallingPackage(callingPackage)
.setCallingFeatureId(callingFeatureId)
.setResolvedType(resolvedType)
.setResultTo(resultTo)
.setResultWho(resultWho)
.setRequestCode(requestCode)
.setStartFlags(startFlags)
.setProfilerInfo(profilerInfo)
.setActivityOptions(bOptions)
.setUserId(userId)
.execute();
}
ActivityStarter.java
int execute() {
try {
***此处省略不少代码***
int res;
synchronized (mService.mGlobalLock) {
final boolean globalConfigWillChange = mRequest.globalConfig != null
&& mService.getGlobalConfiguration().diff(mRequest.globalConfig) != 0;
final ActivityStack stack = mRootWindowContainer.getTopDisplayFocusedStack();
if (stack != null) {
stack.mConfigWillChange = globalConfigWillChange;
}
if (DEBUG_CONFIGURATION) {
Slog.v(TAG_CONFIGURATION, "Starting activity when config will change = "
+ globalConfigWillChange);
}
final long origId = Binder.clearCallingIdentity();
res = resolveToHeavyWeightSwitcherIfNeeded();
if (res != START_SUCCESS) {
return res;
}
//在此处进入executeRequest方法
res = executeRequest(mRequest);
Binder.restoreCallingIdentity(origId);
if (globalConfigWillChange) {
// If the caller also wants to switch to a new configuration, do so now.
// This allows a clean switch, as we are waiting for the current activity
// to pause (so we will not destroy it), and have not yet started the
// next activity.
mService.mAmInternal.enforceCallingPermission(
android.Manifest.permission.CHANGE_CONFIGURATION,
"updateConfiguration()");
if (stack != null) {
stack.mConfigWillChange = false;
}
if (DEBUG_CONFIGURATION) {
Slog.v(TAG_CONFIGURATION,
"Updating to new configuration after starting activity.");
}
mService.updateConfigurationLocked(mRequest.globalConfig, null, false);
}
// Notify ActivityMetricsLogger that the activity has launched.
// ActivityMetricsLogger will then wait for the windows to be drawn and populate
// WaitResult.
mSupervisor.getActivityMetricsLogger().notifyActivityLaunched(launchingState, res,
mLastStartActivityRecord);
return getExternalResult(mRequest.waitResult == null ? res
: waitForResult(res, mLastStartActivityRecord));
}
} finally {
onExecutionComplete();
}
}
private int executeRequest(Request request) {
***这里省略不少***
//重点在这里
mController.doPendingActivityLaunches(false);
mLastStartActivityResult = startActivityUnchecked(r, sourceRecord, voiceSession,
request.voiceInteractor, startFlags, true /* doResume */, checkedOptions, inTask,
restrictedBgActivity, intentGrants);
if (request.outActivity != null) {
request.outActivity[0] = mLastStartActivityRecord;
}
return mLastStartActivityResult;
}
void doPendingActivityLaunches(boolean doResume) {
while (!mPendingActivityLaunches.isEmpty()) {
final PendingActivityLaunch pal = mPendingActivityLaunches.remove(0);
final boolean resume = doResume && mPendingActivityLaunches.isEmpty();
final ActivityStarter starter = obtainStarter(null /* intent */,
"pendingActivityLaunch");
try {
starter.startResolvedActivity(pal.r, pal.sourceRecord, null, null, pal.startFlags,
resume, pal.r.pendingOptions, null, pal.intentGrants);
} catch (Exception e) {
Slog.e(TAG, "Exception during pending activity launch pal=" + pal, e);
pal.sendErrorResult(e.getMessage());
}
}
}
void startResolvedActivity(final ActivityRecord r, ActivityRecord sourceRecord,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
int startFlags, boolean doResume, ActivityOptions options, Task inTask,
NeededUriGrants intentGrants) {
try {
***此处省略不少代码***
mLastStartActivityResult = startActivityUnchecked(r, sourceRecord, voiceSession,
voiceInteractor, startFlags, doResume, options, inTask,
false /* restrictedBgActivity */, intentGrants);
mSupervisor.getActivityMetricsLogger().notifyActivityLaunched(launchingState,
mLastStartActivityResult, mLastStartActivityRecord);
} finally {
onExecutionComplete();
}
}
private int startActivityUnchecked(final ActivityRecord r, ActivityRecord sourceRecord,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
int startFlags, boolean doResume, ActivityOptions options, Task inTask,
boolean restrictedBgActivity, NeededUriGrants intentGrants) {
int result = START_CANCELED;
final ActivityStack startedActivityStack;
try {
mService.deferWindowLayout();
Trace.traceBegin(Trace.TRACE_TAG_WINDOW_MANAGER, "startActivityInner");
result = startActivityInner(r, sourceRecord, voiceSession, voiceInteractor,
startFlags, doResume, options, inTask, restrictedBgActivity, intentGrants);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_WINDOW_MANAGER);
startedActivityStack = handleStartResult(r, result);
mService.continueWindowLayout();
}
postStartActivityProcessing(r, result, startedActivityStack);
return result;
}
int startActivityInner(final ActivityRecord r, ActivityRecord sourceRecord,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
int startFlags, boolean doResume, ActivityOptions options, Task inTask,
boolean restrictedBgActivity, NeededUriGrants intentGrants) {
***此处省略不少代码***
if (mDoResume) {
final ActivityRecord topTaskActivity =
mStartActivity.getTask().topRunningActivityLocked();
if (!mTargetStack.isTopActivityFocusable()
|| (topTaskActivity != null && topTaskActivity.isTaskOverlay()
***此处省略不少代码***
// visible.
mTargetStack.ensureActivitiesVisible(null /* starting */,
0 /* configChanges */, !PRESERVE_WINDOWS);
mTargetStack.getDisplay().mDisplayContent.executeAppTransition();
} else {
// accordingly.
if (mTargetStack.isTopActivityFocusable()
&& !mRootWindowContainer.isTopDisplayFocusedStack(mTargetStack)) {
mTargetStack.moveToFront("startActivityInner");
}
//重点在这里
mRootWindowContainer.resumeFocusedStacksTopActivities(
mTargetStack, mStartActivity, mOptions);
}
}
***此处省略不少代码***
return START_SUCCESS;
}
RootWindowContainer.java
boolean resumeFocusedStacksTopActivities(
ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {
***此处省略不少代码***
for (int displayNdx = getChildCount() - 1; displayNdx >= 0; --displayNdx) {
***此处省略不少代码***
if (!resumedOnDisplay) {
// In cases when there are no valid activities (e.g. device just booted or launcher
// crashed) it's possible that nothing was resumed on a display. Requesting resume
// of top activity in focused stack explicitly will make sure that at least home
// activity is started and resumed, and no recursion occurs.
final ActivityStack focusedStack = display.getFocusedStack();
if (focusedStack != null) {
result |= focusedStack.resumeTopActivityUncheckedLocked(target, targetOptions);
} else if (targetStack == null) {
result |= resumeHomeActivity(null /* prev */, "no-focusable-task",
display.getDefaultTaskDisplayArea());
}
}
}
return result;
}
ActivityStack.java
boolean resumeTopActivityUncheckedLocked(ActivityRecord prev, ActivityOptions options) {
if (mInResumeTopActivity) {
// Don't even start recursing.
return false;
}
boolean result = false;
try {
// Protect against recursion.
mInResumeTopActivity = true;
result = resumeTopActivityInnerLocked(prev, options);
final ActivityRecord next = topRunningActivity(true /* focusableOnly */);
if (next == null || !next.canTurnScreenOn()) {
checkReadyForSleep();
}
} finally {
mInResumeTopActivity = false;
}
return result;
}
private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) {
***此处省略不少代码***
boolean pausing = taskDisplayArea.pauseBackStacks(userLeaving, next);
if (mResumedActivity != null) {
if (DEBUG_STATES) Slog.d(TAG_STATES,
"resumeTopActivityLocked: Pausing " + mResumedActivity);
//停止当前的Activity
pausing |= startPausingLocked(userLeaving, false /* uiSleeping */, next);
}
***此处省略不少代码***
if (next.attachedToProcess()) {
***此处省略不少代码***
} else {
// Whoops, need to restart this activity!
if (!next.hasBeenLaunched) {
next.hasBeenLaunched = true;
} else {
if (SHOW_APP_STARTING_PREVIEW) {
next.showStartingWindow(null /* prev */, false /* newTask */,
false /* taskSwich */);
}
if (DEBUG_SWITCH) Slog.v(TAG_SWITCH, "Restarting: " + next);
}
if (DEBUG_STATES) Slog.d(TAG_STATES, "resumeTopActivityLocked: Restarting " + next);
//启动指定的Activity
mStackSupervisor.startSpecificActivity(next, true, true);
}
return true;
}
final boolean startPausingLocked(boolean userLeaving, boolean uiSleeping,
ActivityRecord resuming) {
if (mPausingActivity != null) {
Slog.wtf(TAG, "Going to pause when pause is already pending for " + mPausingActivity
+ " state=" + mPausingActivity.getState());
if (!shouldSleepActivities()) {
// Avoid recursion among check for sleep and complete pause during sleeping.
// Because activity will be paused immediately after resume, just let pause
// be completed by the order of activity paused from clients.
completePauseLocked(false, resuming);
}
}
ActivityRecord prev = mResumedActivity;
if (prev == null) {
if (resuming == null) {
Slog.wtf(TAG, "Trying to pause when nothing is resumed");
mRootWindowContainer.resumeFocusedStacksTopActivities();
}
return false;
}
if (prev == resuming) {
Slog.wtf(TAG, "Trying to pause activity that is in process of being resumed");
return false;
}
if (DEBUG_STATES) Slog.v(TAG_STATES, "Moving to PAUSING: " + prev);
else if (DEBUG_PAUSE) Slog.v(TAG_PAUSE, "Start pausing: " + prev);
mPausingActivity = prev;
mLastPausedActivity = prev;
mLastNoHistoryActivity = prev.isNoHistory() ? prev : null;
prev.setState(PAUSING, "startPausingLocked");
prev.getTask().touchActiveTime();
clearLaunchTime(prev);
mAtmService.updateCpuStats();
boolean pauseImmediately = false;
if (resuming != null && (resuming.info.flags & FLAG_RESUME_WHILE_PAUSING) != 0) {
// If the flag RESUME_WHILE_PAUSING is set, then continue to schedule the previous
// activity to be paused, while at the same time resuming the new resume activity
// only if the previous activity can't go into Pip since we want to give Pip
// activities a chance to enter Pip before resuming the next activity.
final boolean lastResumedCanPip = prev != null && prev.checkEnterPictureInPictureState(
"shouldResumeWhilePausing", userLeaving);
if (!lastResumedCanPip) {
pauseImmediately = true;
}
}
if (prev.attachedToProcess()) {
if (DEBUG_PAUSE) Slog.v(TAG_PAUSE, "Enqueueing pending pause: " + prev);
try {
EventLogTags.writeWmPauseActivity(prev.mUserId, System.identityHashCode(prev),
prev.shortComponentName, "userLeaving=" + userLeaving);
mAtmService.getLifecycleManager().scheduleTransaction(prev.app.getThread(),
prev.appToken, PauseActivityItem.obtain(prev.finishing, userLeaving,
prev.configChangeFlags, pauseImmediately));
} 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;
}
} else {
mPausingActivity = null;
mLastPausedActivity = null;
mLastNoHistoryActivity = null;
}
// If we are not going to sleep, we want to ensure the device is
// awake until the next activity is started.
if (!uiSleeping && !mAtmService.isSleepingOrShuttingDownLocked()) {
mStackSupervisor.acquireLaunchWakelock();
}
if (mPausingActivity != null) {
// Have the window manager pause its key dispatching until the new
// activity has started. If we're pausing the activity just because
// the screen is being turned off and the UI is sleeping, don't interrupt
// key dispatch; the same activity will pick it up again on wakeup.
if (!uiSleeping) {
prev.pauseKeyDispatchingLocked();
} else if (DEBUG_PAUSE) {
Slog.v(TAG_PAUSE, "Key dispatch not paused for screen off");
}
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;
} else {
prev.schedulePauseTimeout();
return true;
}
} else {
// This activity failed to schedule the
// pause, so just treat it as being paused now.
if (DEBUG_PAUSE) Slog.v(TAG_PAUSE, "Activity not running, resuming next.");
if (resuming == null) {
mRootWindowContainer.resumeFocusedStacksTopActivities();
}
return false;
}
}
ActivityStackSupervisor.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");
}
