从点击桌面app图片开始看，代码如下：
然后就是调用startActivitySafely方法，代码如下：
调用startActivity方法，代码如下 ：
然后调用activity.java中的startActivity方法，代码如下：
然后调用startActivityForResult方法，代码如下：
然后调用Instrumentation.java的execStartActivity方法返回ActivityManagerService的远程接口，代码如下：
可以看到 它其它是前面说的返回ActivityManagerService调用他的startActivity：
调用startActivityAsUser继续调用startActivityMayWait：
解析Intent然后进入startActivityLocked方法检测机制：
创建即将要启动的Activity相关信息:
继续调用startActivityUncheckedLocked方法：
然后通知WindowManagerService服务后判断参数doResume的值是为true。
//源码路径D:\dow\android-5.1.1_r1\android-5.1.1_r1\packages\apps\Launcher2\src\com\android\launcher2\Launcher.java
public void onClick(View v) {
// Make sure that rogue clicks don‘t get through while allapps is launching,or after the
// view has detached (it‘s possible for this to happen if the view is removed mid touch).
if (v.getwindowToken() == null) {
return;
}
if (!mWorkspace.isFinishedSwitchingState()) {
return;
}
Object tag = v.getTag();
if (tag instanceof ShortcutInfo) {
// Open shortcut
final Intent intent = ((ShortcutInfo) tag).intent;
int[] pos = new int[2];
v.getLocationOnScreen(pos);
intent.setSourceBounds(new Rect(pos[0],pos[1],pos[0] + v.getWidth(),pos[1] + v.getHeight()));
boolean success = startActivitySafely(v,intent,tag);
if (success && v instanceof BubbleTextView) {
mWaitingForResume = (BubbleTextView) v;
mWaitingForResume.setStaypressed(true);
}
} else if (tag instanceof FolderInfo) {
if (v instanceof FolderIcon) {
FolderIcon fi = (FolderIcon) v;
handleFolderClick(fi);
}
} else if (v == mAllAppsButton) {
if (isAllAppsVisible()) {
showWorkspace(true);
} else {
onClickAllAppsButton(v);
}
}
}
然后就是调用startActivitySafely方法，代码如下：
boolean startActivitySafely(View v,Intent intent,Object tag) {
boolean success = false;
try {
success = startActivity(v,tag);
} catch (ActivityNotFoundException e) {
Toast.makeText(this,R.string.activity_not_found,Toast.LENGTH_SHORT).show();
Log.e(TAG,"Unable to launch. tag=" + tag + " intent=" + intent,e);
}
return success;
}
调用startActivity方法，代码如下 ：
boolean startActivity(View v,Object tag) {
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
try {
// Only launch using the new animation if the shortcut has not opted out (this is a
// private contract between launcher and may be ignored in the future).
boolean useLaunchAnimation = (v != null) &&
!intent.hasExtra(INTENT_EXTRA_IGnorE_LAUNCH_ANIMATION);
UserHandle user = (UserHandle) intent.getParcelableExtra(ApplicationInfo.EXTRA_PROFILE);
LauncherApps launcherApps = (LauncherApps)
this.getSystemService(Context.LAUNCHER_APPS_SERVICE);
if (useLaunchAnimation) {
ActivityOptions opts = ActivityOptions.makeScaleUpAnimation(v,v.getMeasuredWidth(),v.getMeasuredHeight());
if (user == null || user.equals(android.os.Process.myUserHandle())) {
// Could be launching some bookkeeping activity
startActivity(intent,opts.toBundle());
} else {
launcherApps.startMainActivity(intent.getComponent(),user,intent.getSourceBounds(),opts.toBundle());
}
} else {
if (user == null || user.equals(android.os.Process.myUserHandle())) {
startActivity(intent);
} else {
launcherApps.startMainActivity(intent.getComponent(),null);
}
}
return true;
} catch (SecurityException e) {
Toast.makeText(this,"Launcher does not have the permission to launch " + intent +
". Make sure to create a MAIN intent-filter for the corresponding activity " +
"or use the exported attribute for this activity. "
+ "tag="+ tag + " intent=" + intent,e);
}
return false;
}
然后调用activity.java中的startActivity方法，代码如下：
//路径：D:\dow\android-5.1.1_r1\android-5.1.1_r1\frameworks\base\core\java\android\app\Activity.java
@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);
}
}
然后调用startActivityForResult方法，代码如下：
public void startActivityForResult(Intent intent,int requestCode,@Nullable Bundle options) {
if (mParent == null) {
Instrumentation.ActivityResult ar =
mInstrumentation.execStartActivity(
this,mMainThread.getApplicationThread(),mToken,this,requestCode,options);
if (ar != null) {
mMainThread.sendActivityResult(
mToken,mEmbeddedID,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;
}
final View decor = mWindow != null ? mWindow.peekDecorView() : null;
if (decor != null) {
decor.cancelPendingInputEvents();
}
// Todo Consider clearing/flushing other event sources and events for child windows.
} else {
if (options != null) {
mParent.startActivityFromChild(this,options);
} else {
// Note we want to go through this method for compatibility with
// existing applications that may have overridden it.
mParent.startActivityFromChild(this,requestCode);
}
}
if (options != null && !isTopOfTask()) {
mActivityTransitionState.startExitOutTransition(this,options);
}
}
然后调用Instrumentation.java的execStartActivity方法返回ActivityManagerService的远程接口，代码如下：
public ActivityResult execStartActivity(
Context who,IBinder contextThread,IBinder token,Activity target,Bundle options) {
IApplicationThread whoThread = (IApplicationThread) contextThread;
if (mActivityMonitors != null) {
synchronized (mSync) {
final int N = mActivityMonitors.size();
for (int i=0; i<N; i++) {
final ActivityMonitor am = mActivityMonitors.get(i);
if (am.match(who,null,intent)) {
am.mHits++;
if (am.isBlocking()) {
return requestCode >= 0 ? am.getResult() : null;
}
break;
}
}
}
}
try {
intent.migrateExtraStreamToClipData();
intent.preparetoLeaveProcess();
int result = ActivityManagerNative.getDefault()
.startActivity(whoThread,who.getBasePackageName(),intent.resolveTypeIfNeeded(who.getContentResolver()),token,target != null ? target.mEmbeddedID : null,options);
checkStartActivityResult(result,intent);
} catch (remoteexception e) {
}
return null;
}
调用ActivityManagerNative.java的getDefault()方法，代码如下：
路径：D:\dow\android-5.1.1_r1\android-5.1.1_r1\frameworks\base\core\java\android\app\ActivityManagerNative.java
static public IActivityManager getDefault() {
return gDefault.get();
}
private static final Singleton<IActivityManager> gDefault = new Singleton<IActivityManager>() { protected IActivityManager create() { IBinder b = ServiceManager.getService("activity"); if (false) { Log.v("ActivityManager","default service binder = " + b); } IActivityManager am = asInterface(b); if (false) { Log.v("ActivityManager","default service = " + am); } return am; } };
可以看到 它其它是前面说的返回ActivityManagerService调用他的startActivity：
IBinder b = ServiceManager.getService("activity");
int result = ActivityManagerNative.getDefault()
.startActivity(whoThread,options);
现在我们去看这个服务的源码：
路径：D:\dow\android-5.1.1_r1\android-5.1.1_r1\frameworks\base\services\core\java\com\android\server\am\ActivityManagerService.java
public final int startActivity(IApplicationThread caller,String callingPackage,String resolvedType,IBinder resultTo,String resultWho,int startFlags,ProfilerInfo profilerInfo,Bundle options) {
return startActivityAsUser(caller,callingPackage,resolvedType,resultTo,resultWho,startFlags,profilerInfo,options,UserHandle.getCallingUserId());
}
调用startActivityAsUser继续调用startActivityMayWait：
public final int startActivityAsUser(IApplicationThread caller,Bundle options,int userId) {
enforceNotIsolatedCaller("startActivity");
userId = handleIncomingUser(Binder.getCallingPid(),Binder.getCallingUid(),userId,false,ALLOW_FULL_ONLY,"startActivity",null);
// Todo: Switch to user app stacks here.
return mStackSupervisor.startActivityMayWait(caller,null);
}
//D:\dow\android-5.1.1_r1\android-5.1.1_r1\frameworks\base\services\core\java\com\android\server\am\ActivityStackSupervisor.java
final int startActivityMayWait(IApplicationThread caller,int callingUid,IVoiceInteractionSession voiceSession,IVoiceInteractor voiceInteractor,WaitResult outResult,Configuration config,int userId,IActivityContainer iContainer,TaskRecord inTask) {
// Refuse possible leaked file descriptors
if (intent != null && intent.hasFileDescriptors()) {
throw new IllegalArgumentException("File descriptors passed in Intent");
}
boolean componentSpecified = intent.getComponent() != null;
解析Intent然后进入startActivityLocked方法检测机制：
//D:\dow\android-5.1.1_r1\android-5.1.1_r1\frameworks\base\services\core\java\com\android\server\am\ActivityStackSupervisor.java
ResolveInfo rInfo =
AppGlobals.getPackageManager().resolveIntent(
intent,PackageManager.MATCH_DEFAULT_ONLY
| ActivityManagerService.STOCK_PM_FLAGS,userId);
aInfo = rInfo != null ? rInfo.activityInfo : null;
aInfo = mService.getActivityInfoForUser(aInfo,userId);
} catch (remoteexception e) {
aInfo = null;
}
}
}
}
int res = startActivityLocked(caller,aInfo,voiceSession,voiceInteractor,callingPid,callingUid,realCallingPid,realCallingUid,componentSpecified,container,inTask);
Binder.restoreCallingIdentity(origId);
创建即将要启动的Activity相关信息:
//D:\dow\android-5.1.1_r1\android-5.1.1_r1\frameworks\base\services\core\java\com\android\server\am\ActivityStackSupervisor.java
final int startActivityLocked(IApplicationThread caller,ActivityInfo aInfo,int callingPid,int realCallingPid,int realCallingUid,boolean componentSpecified,ActivityRecord[] outActivity,ActivityContainer container,TaskRecord inTask) {
int err = ActivityManager.START_SUCCESS;
Proce***ecord callerApp = null;
if (caller != null) {
callerApp = mService.getRecordForAppLocked(caller);
if (callerApp != null) {
callingPid = callerApp.pid;
.............
ActivityRecord r = new ActivityRecord(mService,callerApp,mService.mConfiguration,resultRecord,options);
if (outActivity != null) {
outActivity[0] = r;
}
final ActivityStack stack = getFocusedStack();
if (voiceSession == null && (stack.mResumedActivity == null
|| stack.mResumedActivity.info.applicationInfo.uid != callingUid)) {
if (!mService.checkAppSwitchAllowedLocked(callingPid,"Activity start")) {
PendingActivityLaunch pal =
new PendingActivityLaunch(r,sourceRecord,stack);
mPendingActivityLaunches.add(pal);
ActivityOptions.abort(options);
return ActivityManager.START_SWITCHES_CANCELED;
}
}
继续调用startActivityUncheckedLocked方法：
mService.mDidAppSwitch = true;
}
doPendingActivityLaunchesLocked(false);
err = startActivityUncheckedLocked(r,true,inTask);
然后通知WindowManagerService服务后判断参数doResume的值是为true。
// sure we have correctly resumed the top activity.
if (doResume) {
resumetopActivitiesLocked(targetStack,options);
// Make sure to notify Keyguard as well if we are not running an app
// transition later.
if (!movedToFront) {
notifyActivityDrawnForKeyguard();
}
} else {
ActivityOptions.abort(options);
}
return ActivityManager.START_RETURN_INTENT_TO_CALLER;
}
if ((launchFl
