Activity的Token对象
什么是Token?
Token是ActivityRecord静态内部类，继承于IApplicationToken.Stub，是AMS为了客户端新启动的Activity所创建，字面上理解它是具有代表Activity令牌的一个Binder。
这个Binder是AMS为Activity创建的一个唯一标识，AMS进程管理App进程的Activity的生命周期，所以用可以跨进程的Binder来标识Activity最合适不过。
Token何时创建？
AMS在创建启动Activity之前创建了ActivityRecord，ActivityRecord包含了待创建Activity所有的信息，并在构造函数中创建了Token，最终Activity创建好之后会得到它在客户端的本地Binder代理
Token
Token继承IApplicationToken.Stub，本质上是一个Binder对象
static class Token extends IApplicationToken.Stub {
private final WeakReference<ActivityRecord> weakActivity;
private final String name;
Token(ActivityRecord activity, Intent intent) {
weakActivity = new WeakReference<>(activity);
name = intent.getComponent().flattenToShortString();
}
在构建ActivityRecord的时候就会创建一个Token对象，ActivityRecord持有该对象
ActivityRecord(ActivityManagerService _service, ProcessRecord _caller, int _launchedFromPid,
int _launchedFromUid, String _launchedFromPackage, Intent _intent, String _resolvedType,
ActivityInfo aInfo, Configuration _configuration,
ActivityRecord _resultTo, String _resultWho, int _reqCode,
boolean _componentSpecified, boolean _rootVoiceInteraction,
ActivityStackSupervisor supervisor, ActivityOptions options,
ActivityRecord sourceRecord) {
service = _service;
appToken = new Token(this, _intent);
ActivityRecord是Activity在服务端AMS中的描述，保存了所有的activity信息，包括启动模式flag，包名，进程名
我们都知道Activity是有页面显示的，也就是窗口，wms是负责管理当前系统中所有的窗口，我们都知道activity在ams中是通过栈的形式被管理的，其实在wms中数据结构和ams是一一对应的，token有一个很重要的作用就是窗口分组的依据，我们通过这个token就能找到对应的窗口信息，在启动一个activity的过程中token是会从ams传递到wms和应用程序，我们分析下这个过程
Token从ams传递到wms的过程
我们知道在activity启动过程有会调用到ActivityStarter::startActivityUnchecked
mTargetStack.startActivityLocked(mStartActivity, topFocused, newTask, mKeepCurTransition,
mOptions);------------>第一个关键点
if (mDoResume) {
final ActivityRecord topTaskActivity =
mStartActivity.getTask().topRunningActivityLocked();
if (!mTargetStack.isFocusable()
|| (topTaskActivity != null && topTaskActivity.mTaskOverlay
&& mStartActivity != topTaskActivity)) {
// If the activity is not focusable, we can't resume it, but still would like to
// make sure it becomes visible as it starts (this will also trigger entry
// animation). An example of this are PIP activities.
// Also, we don't want to resume activities in a task that currently has an overlay
// as the starting activity just needs to be in the visible paused state until the
// over is removed.
mTargetStack.ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
// Go ahead and tell window manager to execute app transition for this activity
// since the app transition will not be triggered through the resume channel.
mService.mWindowManager.executeAppTransition();
} else {
// If the target stack was not previously focusable (previous top running activity
// on that stack was not visible) then any prior calls to move the stack to the
// will not update the focused stack. If starting the new activity now allows the
// task stack to be focusable, then ensure that we now update the focused stack
// accordingly.
if (mTargetStack.isFocusable() && !mSupervisor.isFocusedStack(mTargetStack)) {
mTargetStack.moveToFront("startActivityUnchecked");
}
mSupervisor.resumeFocusedStackTopActivityLocked(mTargetStack, mStartActivity,
mOptions);------->第二个关键点
}
ActivityStack::startActivityLocked
// Slot the activity into the history stack and proceed
if (DEBUG_ADD_REMOVE) Slog.i(TAG, "Adding activity " + r + " to stack to task " + task,
new RuntimeException("here").fillInStackTrace());
// TODO: Need to investigate if it is okay for the controller to already be created by the
// time we get to this point. I think it is, but need to double check.
// Use test in b/34179495 to trace the call path.
if (r.getWindowContainerController() == null) {
r.createWindowContainer();------------->根据token创建AppWindowToken
}
task.setFrontOfTask();---------------------->将任务栈放在栈顶中
AppWindowContainerController
void createWindowContainer() {
if (mWindowContainerController != null) {
throw new IllegalArgumentException("Window container=" + mWindowContainerController
+ " already created for r=" + this);
}
inHistory = true;
final TaskWindowContainerController taskController = task.getWindowContainerController();
// TODO(b/36505427): Maybe this call should be moved inside updateOverrideConfiguration()
task.updateOverrideConfigurationFromLaunchBounds();
// Make sure override configuration is up-to-date before using to create window controller.
updateOverrideConfiguration();
mWindowContainerController = new AppWindowContainerController(taskController, appToken,
this, Integer.MAX_VALUE /* add on top */, info.screenOrientation, fullscreen,
(info.flags & FLAG_SHOW_FOR_ALL_USERS) != 0, info.configChanges,
task.voiceSession != null, mLaunchTaskBehind, isAlwaysFocusable(),
appInfo.targetSdkVersion, mRotationAnimationHint,
ActivityManagerService.getInputDispatchingTimeoutLocked(this) * 1000000L);
task.addActivityToTop(this);
// When an activity is started directly into a split-screen fullscreen stack, we need to
// update the initial multi-window modes so that the callbacks are scheduled correctly when
// the user leaves that mode.
mLastReportedMultiWindowMode = inMultiWindowMode();
mLastReportedPictureInPictureMode = inPinnedWindowingMode();
}
public AppWindowContainerController(TaskWindowContainerController taskController,
IApplicationToken token, AppWindowContainerListener listener, int index,
int requestedOrientation, boolean fullscreen, boolean showForAllUsers, int configChanges,
boolean voiceInteraction, boolean launchTaskBehind, boolean alwaysFocusable,
int targetSdkVersion, int rotationAnimationHint, long inputDispatchingTimeoutNanos,
WindowManagerService service) {
super(listener, service);
mHandler = new H(service.mH.getLooper());
mToken = token;
synchronized(mWindowMap) {
AppWindowToken atoken = mRoot.getAppWindowToken(mToken.asBinder());
if (atoken != null) {
// TODO: Should this throw an exception instead?
Slog.w(TAG_WM, "Attempted to add existing app token: " + mToken);
return;
}
final Task task = taskController.mContainer;
if (task == null) {
throw new IllegalArgumentException("AppWindowContainerController: invalid "
+ " controller=" + taskController);
}
atoken = createAppWindow(mService, token, voiceInteraction, task.getDisplayContent(),
inputDispatchingTimeoutNanos, fullscreen, showForAllUsers, targetSdkVersion,
requestedOrientation, rotationAnimationHint, configChanges, launchTaskBehind,
alwaysFocusable, this);
if (DEBUG_TOKEN_MOVEMENT || DEBUG_ADD_REMOVE) Slog.v(TAG_WM, "addAppToken: " + atoken
+ " controller=" + taskController + " at " + index);
task.addChild(atoken, index);
}
}
AppWindowToken createAppWindow(WindowManagerService service, IApplicationToken token,
boolean voiceInteraction, DisplayContent dc, long inputDispatchingTimeoutNanos,
boolean fullscreen, boolean showForAllUsers, int targetSdk, int orientation,
int rotationAnimationHint, int configChanges, boolean launchTaskBehind,
boolean alwaysFocusable, AppWindowContainerController controller) {
return new AppWindowToken(service, token, voiceInteraction, dc,
inputDispatchingTimeoutNanos, fullscreen, showForAllUsers, targetSdk, orientation,
rotationAnimationHint, configChanges, launchTaskBehind, alwaysFocusable,
controller);----------->创建AppWindowToken对象
}
首先是创建一个AppWindowContainerController的对象，其中的参数appToken就是ActivityRecord的成员变量mToken，此时ActivityRecord的mtoken对象就传递到了wms
Token从AMS传递到app端
我们继续分析activity的启动流程，我们知道在启动activity中有一步就是realStartActivityLocked
// Create activity launch transaction.
final ClientTransaction clientTransaction = ClientTransaction.obtain(app.thread,
r.appToken);
clientTransaction.addCallback(LaunchActivityItem.obtain(new Intent(r.intent),
System.identityHashCode(r), r.info,
// TODO: Have this take the merged configuration instead of separate global
// and override configs.
mergedConfiguration.getGlobalConfiguration(),
mergedConfiguration.getOverrideConfiguration(), r.compat,
r.launchedFromPackage, task.voiceInteractor, app.repProcState, r.icicle,
r.persistentState, results, newIntents, mService.isNextTransitionForward(),
profilerInfo));
// Set desired final state.
final ActivityLifecycleItem lifecycleItem;
if (andResume) {
lifecycleItem = ResumeActivityItem.obtain(mService.isNextTransitionForward());
} else {
lifecycleItem = PauseActivityItem.obtain();
}
clientTransaction.setLifecycleStateRequest(lifecycleItem);
// Schedule transaction.
mService.getLifecycleManager().scheduleTransaction(clientTransaction);
void scheduleTransaction(ClientTransaction transaction) throws RemoteException {
final IApplicationThread client = transaction.getClient();
transaction.schedule();
if (!(client instanceof Binder)) {
// If client is not an instance of Binder - it's a remote call and at this point it is
// safe to recycle the object. All objects used for local calls will be recycled after
// the transaction is executed on client in ActivityThread.
transaction.recycle();
}
}
public void schedule() throws RemoteException {
mClient.scheduleTransaction(this);
}
public void scheduleTransaction(ClientTransaction transaction) throws RemoteException {
ActivityThread.this.scheduleTransaction(transaction);
//
}
void scheduleTransaction(ClientTransaction transaction) {
transaction.preExecute(this);
sendMessage(ActivityThread.H.EXECUTE_TRANSACTION, transaction);
}
case EXECUTE_TRANSACTION:
final ClientTransaction transaction = (ClientTransaction) msg.obj;
mTransactionExecutor.execute(transaction);
if (isSystem()) {
// Client transactions inside system process are recycled on the client side
// instead of ClientLifecycleManager to avoid being cleared before this
// message is handled.
transaction.recycle();
}
// TODO(lifecycler): Recycle locally scheduled transactions.
break;
public void execute(ClientTransaction transaction) {
final IBinder token = transaction.getActivityToken();
log("Start resolving transaction for client: " + mTransactionHandler + ", token: " + token);
executeCallbacks(transaction);
executeLifecycleState(transaction);
mPendingActions.clear();
log("End resolving transaction");
}
public void executeCallbacks(ClientTransaction transaction) {
final List<ClientTransactionItem> callbacks = transaction.getCallbacks();
if (callbacks == null) {
// No callbacks to execute, return early.
return;
}
log("Resolving callbacks");
final IBinder token = transaction.getActivityToken();
ActivityClientRecord r = mTransactionHandler.getActivityClient(token);
// In case when post-execution state of the last callback matches the final state requested
// for the activity in this transaction, we won't do the last transition here and do it when
// moving to final state instead (because it may contain additional parameters from server).
final ActivityLifecycleItem finalStateRequest = transaction.getLifecycleStateRequest();
final int finalState = finalStateRequest != null ? finalStateRequest.getTargetState()
: UNDEFINED;
// Index of the last callback that requests some post-execution state.
final int lastCallbackRequestingState = lastCallbackRequestingState(transaction);
final int size = callbacks.size();
for (int i = 0; i < size; ++i) {
final ClientTransactionItem item = callbacks.get(i);
log("Resolving callback: " + item);
final int postExecutionState = item.getPostExecutionState();
final int closestPreExecutionState = mHelper.getClosestPreExecutionState(r,
item.getPostExecutionState());
if (closestPreExecutionState != UNDEFINED) {
cycleToPath(r, closestPreExecutionState);
}
item.execute(mTransactionHandler, token, mPendingActions);//数据类型LaunchActivityItem
item.postExecute(mTransactionHandler, token, mPendingActions);
if (r == null) {
// Launch activity request will create an activity record.
r = mTransactionHandler.getActivityClient(token);
}
if (postExecutionState != UNDEFINED && r != null) {
// Skip the very last transition and perform it by explicit state request instead.
final boolean shouldExcludeLastTransition =
i == lastCallbackRequestingState && finalState == postExecutionState;
cycleToPath(r, postExecutionState, shouldExcludeLastTransition);
}
}
}
LaunchActivityItem::execute
public void execute(ClientTransactionHandler client, IBinder token,
PendingTransactionActions pendingActions) {
Trace.traceBegin(TRACE_TAG_ACTIVITY_MANAGER, "activityStart");
ActivityClientRecord r = new ActivityClientRecord(token, mIntent, mIdent, mInfo,
mOverrideConfig, mCompatInfo, mReferrer, mVoiceInteractor, mState, mPersistentState,
mPendingResults, mPendingNewIntents, mIsForward,
mProfilerInfo, client);
client.handleLaunchActivity(r, pendingActions, null /* customIntent */);
Trace.traceEnd(TRACE_TAG_ACTIVITY_MANAGER);
}
public Activity handleLaunchActivity(ActivityClientRecord r,
PendingTransactionActions pendingActions, Intent customIntent) {
// If we are getting ready to gc after going to the background, well
// we are back active so skip it.
unscheduleGcIdler();
mSomeActivitiesChanged = true;
if (r.profilerInfo != null) {
mProfiler.setProfiler(r.profilerInfo);
mProfiler.startProfiling();
}
// Make sure we are running with the most recent config.
handleConfigurationChanged(null, null);
if (localLOGV) Slog.v(
TAG, "Handling launch of " + r);
// Initialize before creating the activity
if (!ThreadedRenderer.sRendererDisabled) {
GraphicsEnvironment.earlyInitEGL();
}
WindowManagerGlobal.initialize();
final Activity a = performLaunchActivity(r, customIntent);
private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent) {
ActivityInfo aInfo = r.activityInfo;
if (r.packageInfo == null) {
r.packageInfo = getPackageInfo(aInfo.applicationInfo, r.compatInfo,
Context.CONTEXT_INCLUDE_CODE);
}
ComponentName component = r.intent.getComponent();
if (component == null) {
component = r.intent.resolveActivity(
mInitialApplication.getPackageManager());
r.intent.setComponent(component);
}
if (r.activityInfo.targetActivity != null) {
component = new ComponentName(r.activityInfo.packageName,
r.activityInfo.targetActivity);
}
ContextImpl appContext = createBaseContextForActivity(r);
Activity activity = null;
try {
java.lang.ClassLoader cl = appContext.getClassLoader();
activity = mInstrumentation.newActivity(
cl, component.getClassName(), r.intent);
StrictMode.incrementExpectedActivityCount(activity.getClass());
r.intent.setExtrasClassLoader(cl);
r.intent.prepareToEnterProcess();
if (r.state != null) {
r.state.setClassLoader(cl);
}
} catch (Exception e) {
if (!mInstrumentation.onException(activity, e)) {
throw new RuntimeException(
"Unable to instantiate activity " + component
+ ": " + e.toString(), e);
}
}
try {
Application app = r.packageInfo.makeApplication(false, mInstrumentation);
if (localLOGV) Slog.v(TAG, "Performing launch of " + r);
if (localLOGV) Slog.v(
TAG, r + ": app=" + app
+ ", appName=" + app.getPackageName()
+ ", pkg=" + r.packageInfo.getPackageName()
+ ", comp=" + r.intent.getComponent().toShortString()
+ ", dir=" + r.packageInfo.getAppDir());
if (activity != null) {
CharSequence title = r.activityInfo.loadLabel(appContext.getPackageManager());
Configuration config = new Configuration(mCompatConfiguration);
if (r.overrideConfig != null) {
config.updateFrom(r.overrideConfig);
}
if (DEBUG_CONFIGURATION) Slog.v(TAG, "Launching activity "
+ r.activityInfo.name + " with config " + config);
Window window = null;
if (r.mPendingRemoveWindow != null && r.mPreserveWindow) {
window = r.mPendingRemoveWindow;
r.mPendingRemoveWindow = null;
r.mPendingRemoveWindowManager = null;
}
appContext.setOuterContext(activity);
activity.attach(appContext, this, getInstrumentation(), r.token,
r.ident, app, r.intent, r.activityInfo, title, r.parent,
r.embeddedID, r.lastNonConfigurationInstances, config,
r.referrer, r.voiceInteractor, window, r.configCallback);
调用activity的attch方法将token传递给了activity
这样token就保存在ams，wms和app中
简单总结
过程：Activity通过PhoneWindow把Token放到DecorView的WindowManager.LayoutParams中。然后App进程向WMS发起IPC，WMS拿到Token保存到WindowState，最终存储到WMS的mWindowMap中。
Token对于WMS的作用？
Activity在创建Token后，在ActivityStarter.startActivityLocked()方法中创建WindowToken，然后以Token和WindowToken为键值存储在DisplayContent的mTokenMap中(点击查看)。当WMS调用addWindow添加Window时候，会使用Activity传过来的Token去mTokenMap查找，来验证Token的合法性。
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