不論你的activity是繼承自AppCompateActivity還是Activity，最終startActivity都會走到Activity中的方法
預設設定參數bundl為null
@Override
public void startActivity(Intent intent) {
this.startActivity(intent, null);
}
預設設定了requestCode也為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);
}
}
最終startActivity會走到這個方法裡來，可見啟動activity有三種參數的設定，intent，bundle，requestCode,
隻不過預設後兩個都可以為null
/**
* Launch an activity for which you would like a result when it finished.
* When this activity exits, your
* onActivityResult() method will be called with the given requestCode.
* Using a negative requestCode is the same as calling
* {@link #startActivity} (the activity is not launched as a sub-activity).
*
* <p>Note that this method should only be used with Intent protocols
* that are defined to return a result. In other protocols (such as
* {@link Intent#ACTION_MAIN} or {@link Intent#ACTION_VIEW}), you may
* not get the result when you expect. For example, if the activity you
* are launching uses {@link Intent#FLAG_ACTIVITY_NEW_TASK}, it will not
* run in your task and thus you will immediately receive a cancel result.
*
* <p>As a special case, if you call startActivityForResult() with a requestCode
* >= 0 during the initial onCreate(Bundle savedInstanceState)/onResume() of your
* activity, then your window will not be displayed until a result is
* returned back from the started activity. This is to avoid visible
* flickering when redirecting to another activity.
*
* <p>This method throws {@link android.content.ActivityNotFoundException}
* if there was no Activity found to run the given Intent.
*
* @param intent The intent to start.
* @param requestCode If >= 0, this code will be returned in
* onActivityResult() when the activity exits.
* @param options Additional options for how the Activity should be started.
* See {@link android.content.Context#startActivity(Intent, Bundle)}
* Context.startActivity(Intent, Bundle)} for more details.
*
* @throws android.content.ActivityNotFoundException
*
* @see #startActivity
*/
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);
...省略部分代碼...
} 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);
}
}
}
在Instrumentation類中找到這個方法
/**
* Execute a startActivity call made by the application. The default
* implementation takes care of updating any active {@link ActivityMonitor}
* objects and dispatches this call to the system activity manager; you can
* override this to watch for the application to start an activity, and
* modify what happens when it does.
*
* <p>This method returns an {@link ActivityResult} object, which you can
* use when intercepting application calls to avoid performing the start
* activity action but still return the result the application is
* expecting. To do this, override this method to catch the call to start
* activity so that it returns a new ActivityResult containing the results
* you would like the application to see, and don't call up to the super
* class. Note that an application is only expecting a result if
* <var>requestCode</var> is >= 0.
*
* <p>This method throws {@link android.content.ActivityNotFoundException}
* if there was no Activity found to run the given Intent.
*
* @param who The Context from which the activity is being started.
* @param contextThread The main thread of the Context from which the activity
* is being started.
* @param token Internal token identifying to the system who is starting
* the activity; may be null.
* @param target Which activity is performing the start (and thus receiving
* any result); may be null if this call is not being made
* from an activity.
* @param intent The actual Intent to start.
* @param requestCode Identifier for this request's result; less than zero
* if the caller is not expecting a result.
* @param options Addition options.
*
* @return To force the return of a particular result, return an
* ActivityResult object containing the desired data; otherwise
* return null. The default implementation always returns null.
*
* @throws android.content.ActivityNotFoundException
*
* @see Activity#startActivity(Intent)
* @see Activity#startActivityForResult(Intent, int)
* @see Activity#startActivityFromChild
*
* {@hide}
*/
public ActivityResult execStartActivity(
Context who, IBinder contextThread, IBinder token, Activity target,
Intent intent, int requestCode, Bundle options) {
...省略部分代碼,設定一些參數...
try {
...省略部分代碼,設定一些參數...
int result = ActivityManager.getService()
.startActivity(whoThread, who.getBasePackageName(), intent,
intent.resolveTypeIfNeeded(who.getContentResolver()),
token, target != null ? target.mEmbeddedID : null,
requestCode, 0, null, options);
//異常檢測
checkStartActivityResult(result, intent);
} catch (RemoteException e) {
throw new RuntimeException("Failure from system", e);
}
return null;
}
找到ActivityManager.getService()得到的對象
/**
* @hide
*/
public static IActivityManager getService() {
return IActivityManagerSingleton.get();
}
其中IActivityManagerSingleton是
private static final Singleton<IActivityManager> IActivityManagerSingleton =
new Singleton<IActivityManager>() {
@Override
protected IActivityManager create() {
final IBinder b = ServiceManager.getService(Context.ACTIVITY_SERVICE);
final IActivityManager am = IActivityManager.Stub.asInterface(b);
return am;
}
};
WX20180323-130247.png
可見，get方法最終傳回的就是子類重寫create方法得到的IActivityManager，它是一個接口，沒有找到api26的源碼，先看api21的吧，應該出入不大
public interface IActivityManager extends IInterface { 1
public int startActivity(IApplicationThread caller,
Intent intent, String resolvedType, Uri[] grantedUriPermissions,
int grantedMode, IBinder resultTo, String resultWho,int requestCode,
boolean onlyIfNeeded, boolean debug) throws RemoteException; 2
public boolean finishActivity(IBinder token,int code, Intent data)
throws RemoteException;
public int broadcastIntent(IApplicationThread caller, Intent intent,
String resolvedType, IIntentReceiver resultTo, int resultCode,
String resultData, Bundle map, String requiredPermission,
boolean serialized, boolean sticky) throws RemoteException;
public ComponentName startService(IApplicationThread caller, Intent service,
String resolvedType) throws RemoteException;
public int bindService(IApplicationThread caller, IBinder token,
Intent service, String resolvedType,
IServiceConnection connection, int flags)throws RemoteException;
...
String descriptor = "android.app.IActivityManager"; 3
int START_RUNNING_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION;
int HANDLE_APPLICATION_ERROR_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+1;
int START_ACTIVITY_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+2;
int UNHANDLED_BACK_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+3;
int OPEN_CONTENT_URI_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+4; 4
...
}
與根據aidl定義生成的接口類一樣，IActivityManager也是基于IInterface生成的接口類，于是在這裡我們隻會定義接口方法，而不提供具體實作。
對于每一個需要實作接口方法而言，因為每個方法都将是跨程序的調用，是以每個方法都必須抛出Remote Exception。
作為使用Binder傳輸對象，都需要一個DESCRIPTOR作為傳輸時的辨別，于是在Binder接收時會以這個Token作為驗證傳輸是否有效的憑據。
雖然不是自動生成，但在這一接口類也會定義一系列Binder指令，Binder指令都是從IBinder.FIRST_CALL_TRANSACTION開始，其他指令都會通過+1進行Binder指令的統一化。
IActiivtyManager接口類,這是一段來自網上的解釋：
在建立了Intent之後，大體上會有三種Intent的發送方式，startActivity()|startActivityForResult()來啟動一個Activity，startService()|bindService()來啟動一個Service，以及sendBroadcast()來發送廣播消息。而在Android内部實作上，Intent的發送，大緻都如下圖所示：
1350564638_4423.png
Intent的發送，分别有可能通過Context的startActivity()、startService()、sendBroadcast()三個出口進行發送。Context由Framework實作的ContextImpl來提供具體的發送功能，在ContextImpl類裡會經過不同的特殊處理，比如在startActivity()之上會再套接一層execStartActivity()方法來驅動Instrumentation測試架構，但最終都會通過ActivityManagerNative類來通路到一個處理Intent請求的gDefault對象。正如我們看到的gDefault，實際上是Singleton<IActivityManager>生成的程序唯一的IActivityManager對象。于是，最終，所有的Intent，都會通過IActivityManager來走入Activity、Service與Broadcast三個不同的處理方法。
如果是按照aidl的标準寫法，此時我們理論上應該會在IAcitvityManager.java的同一級目錄裡找到一個IActivityManager.aidl檔案。但很不幸，我們找不到這麼一個檔案，跟我們前面見到的aidl實作似乎很不一樣。所有需要使用到AIDL實作的地方，總需要某種機制可以得到IBinder引用，而像ActivityManager，還有稍後會介紹的一個ServiceManager，都會是嘗試去擷取一個IBinder引用的，這時便有了個“雞與蛋”的問題，為了簡化邏輯，于是這一層便是繞開AIDL，直接實作IActivityManager接口類。
仔細看一下的話，其實IActivityManager.java與通過aidl自動生成的檔案很類似，基本構成都是一樣,如上
可見，IActivityManager的作用是很大的，未來我們想通過動态代理實作hook技術，也離不開這個接口，
接下來我們回到activity的啟動流程中去，因為IActivityManager是個接口，是以
ActivityManager.getService()
.startActivity(whoThread, who.getBasePackageName(), intent,
intent.resolveTypeIfNeeded(who.getContentResolver()),
token, target != null ? target.mEmbeddedID : null,
requestCode, 0, null, options);
startActivity這個方法實際上是調用的IActivityManager的實作類中的方法，那麼這個實作類是什麼呢？
ActivityManagerNative 是一個抽象類，它實作了IActivityManager接口，并且内部又一個内部類ActivityManagerProxy實作了IActivityManager并且重寫了startActivity方法，但是我們目前暫且不看這個，
ActivityManagerNative有一個字類ActivityManagerService,ActivityManagerService中定義了startActivity這個方法，我們看源碼：
@Override
public final int startActivity(IApplicationThread caller, String callingPackage,
Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
int startFlags, ProfilerInfo profilerInfo, Bundle bOptions) {
return startActivityAsUser(caller, callingPackage, intent, resolvedType, resultTo,
resultWho, requestCode, startFlags, profilerInfo, bOptions,
UserHandle.getCallingUserId());
}
@Override
public final int startActivityAsUser(IApplicationThread caller, String callingPackage,
Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
int startFlags, ProfilerInfo profilerInfo, Bundle bOptions, int userId) {
enforceNotIsolatedCaller("startActivity");
userId = mUserController.handleIncomingUser(Binder.getCallingPid(), Binder.getCallingUid(),
userId, false, ALLOW_FULL_ONLY, "startActivity", null);
// TODO: Switch to user app stacks here.
return mActivityStarter.startActivityMayWait(caller, -1, callingPackage, intent,
resolvedType, null, null, resultTo, resultWho, requestCode, startFlags,
profilerInfo, null, null, bOptions, false, userId, null, null,
"startActivityAsUser");
}
進入了ActivityStarter類中
final int startActivityMayWait(IApplicationThread caller, int callingUid,
String callingPackage, Intent intent, String resolvedType,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
IBinder resultTo, String resultWho, int requestCode, int startFlags,
ProfilerInfo profilerInfo, WaitResult outResult,
Configuration globalConfig, Bundle bOptions, boolean ignoreTargetSecurity, int userId,
IActivityContainer iContainer, TaskRecord inTask, String reason) {
......
final ActivityRecord[] outRecord = new ActivityRecord[1];
int res = startActivityLocked(caller, intent, ephemeralIntent, resolvedType,
aInfo, rInfo, voiceSession, voiceInteractor,
resultTo, resultWho, requestCode, callingPid,
callingUid, callingPackage, realCallingPid, realCallingUid, startFlags,
options, ignoreTargetSecurity, componentSpecified, outRecord, container,
inTask, reason);
......
}
int startActivityLocked(IApplicationThread caller, Intent intent, Intent ephemeralIntent,
String resolvedType, ActivityInfo aInfo, ResolveInfo rInfo,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
IBinder resultTo, String resultWho, int requestCode, int callingPid, int callingUid,
String callingPackage, int realCallingPid, int realCallingUid, int startFlags,
ActivityOptions options, boolean ignoreTargetSecurity, boolean componentSpecified,
ActivityRecord[] outActivity, ActivityStackSupervisor.ActivityContainer container,
TaskRecord inTask, String reason) {
if (TextUtils.isEmpty(reason)) {
throw new IllegalArgumentException("Need to specify a reason.");
}
mLastStartReason = reason;
mLastStartActivityTimeMs = System.currentTimeMillis();
mLastStartActivityRecord[0] = null;
mLastStartActivityResult = startActivity(caller, intent, ephemeralIntent, resolvedType,
aInfo, rInfo, voiceSession, voiceInteractor, resultTo, resultWho, requestCode,
callingPid, callingUid, callingPackage, realCallingPid, realCallingUid, startFlags,
options, ignoreTargetSecurity, componentSpecified, mLastStartActivityRecord,
container, inTask);
if (outActivity != null) {
// mLastStartActivityRecord[0] is set in the call to startActivity above.
outActivity[0] = mLastStartActivityRecord[0];
}
return mLastStartActivityResult;
}
/** DO NOT call this method directly. Use {@link #startActivityLocked} instead. */
private int startActivity(IApplicationThread caller, Intent intent, Intent ephemeralIntent,
String resolvedType, ActivityInfo aInfo, ResolveInfo rInfo,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
IBinder resultTo, String resultWho, int requestCode, int callingPid, int callingUid,
String callingPackage, int realCallingPid, int realCallingUid, int startFlags,
ActivityOptions options, boolean ignoreTargetSecurity, boolean componentSpecified,
ActivityRecord[] outActivity, ActivityStackSupervisor.ActivityContainer container,
TaskRecord inTask) {
......
return startActivity(r, sourceRecord, voiceSession, voiceInteractor, startFlags, true,
options, inTask, outActivity);
}
private int startActivity(final ActivityRecord r, ActivityRecord sourceRecord,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
int startFlags, boolean doResume, ActivityOptions options, TaskRecord inTask,
ActivityRecord[] outActivity) {
int result = START_CANCELED;
try {
mService.mWindowManager.deferSurfaceLayout();
result = startActivityUnchecked(r, sourceRecord, voiceSession, voiceInteractor,
startFlags, doResume, options, inTask, outActivity);
} finally {
// If we are not able to proceed, disassociate the activity from the task. Leaving an
// activity in an incomplete state can lead to issues, such as performing operations
// without a window container.
if (!ActivityManager.isStartResultSuccessful(result)
&& mStartActivity.getTask() != null) {
mStartActivity.getTask().removeActivity(mStartActivity);
}
mService.mWindowManager.continueSurfaceLayout();
}
postStartActivityProcessing(r, result, mSupervisor.getLastStack().mStackId, mSourceRecord,
mTargetStack);
return result;
}
// Note: This method should only be called from {@link startActivity}.
private int startActivityUnchecked(final ActivityRecord r, ActivityRecord sourceRecord,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
int startFlags, boolean doResume, ActivityOptions options, TaskRecord inTask,
ActivityRecord[] outActivity) {
......
mTargetStack.startActivityLocked(mStartActivity, topFocused, newTask, mKeepCurTransition,
mOptions);
......
}
進入了ActivityStack類中
final void startActivityLocked(ActivityRecord r, ActivityRecord focusedTopActivity,
boolean newTask, boolean keepCurTransition, ActivityOptions options) {
.......
if (r.mLaunchTaskBehind) {
// Don't do a starting window for mLaunchTaskBehind. More importantly make sure we
// tell WindowManager that r is visible even though it is at the back of the stack.
r.setVisibility(true);
ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
} else if (SHOW_APP_STARTING_PREVIEW && doShow) {
// Figure out if we are transitioning from another activity that is
// "has the same starting icon" as the next one. This allows the
// window manager to keep the previous window it had previously
// created, if it still had one.
TaskRecord prevTask = r.getTask();
ActivityRecord prev = prevTask.topRunningActivityWithStartingWindowLocked();
if (prev != null) {
// We don't want to reuse the previous starting preview if:
// (1) The current activity is in a different task.
if (prev.getTask() != prevTask) {
prev = null;
}
// (2) The current activity is already displayed.
else if (prev.nowVisible) {
prev = null;
}
}
r.showStartingWindow(prev, newTask, isTaskSwitch(r, focusedTopActivity));
}
.......
}
進入ActivityStack的resumeTopActivityInnerLocked()方法
private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) {
......
if (mResumedActivity != null) {
if (DEBUG_STATES) Slog.d(TAG_STATES,
"resumeTopActivityLocked: Pausing " + mResumedActivity);
pausing |= startPausingLocked(userLeaving, false, next, false);
}
......
}
/**
* Start pausing the currently resumed activity. It is an error to call this if there
* is already an activity being paused or there is no resumed activity.
*
* @param userLeaving True if this should result in an onUserLeaving to the current activity.
* @param uiSleeping True if this is happening with the user interface going to sleep (the
* screen turning off).
* @param resuming The activity we are currently trying to resume or null if this is not being
* called as part of resuming the top activity, so we shouldn't try to instigate
* a resume here if not null.
* @param pauseImmediately True if the caller does not want to wait for the activity callback to
* complete pausing.
* @return Returns true if an activity now is in the PAUSING state, and we are waiting for
* it to tell us when it is done.
*/
final boolean startPausingLocked(boolean userLeaving, boolean uiSleeping,
ActivityRecord resuming, boolean pauseImmediately) {
......
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, 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;
}
......
}
進入到ActivityThread内部類ApplicationThread類中
private class ApplicationThread extends IApplicationThread.Stub {
......
public final void schedulePauseActivity(IBinder token, boolean finished,
boolean userLeaving, int configChanges, boolean dontReport) {
int seq = getLifecycleSeq();
if (DEBUG_ORDER) Slog.d(TAG, "pauseActivity " + ActivityThread.this
+ " operation received seq: " + seq);
sendMessage(
finished ? H.PAUSE_ACTIVITY_FINISHING : H.PAUSE_ACTIVITY,
token,
(userLeaving ? USER_LEAVING : 0) | (dontReport ? DONT_REPORT : 0),
configChanges,
seq);
}
......
}
找到接收消息的handler
public void handleMessage(Message msg) {
if (DEBUG_MESSAGES) Slog.v(TAG, ">>> handling: " + codeToString(msg.what));
switch (msg.what) {
......
case PAUSE_ACTIVITY: {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "activityPause");
SomeArgs args = (SomeArgs) msg.obj;
handlePauseActivity((IBinder) args.arg1, false,
(args.argi1 & USER_LEAVING) != 0, args.argi2,
(args.argi1 & DONT_REPORT) != 0, args.argi3);
maybeSnapshot();
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
} break;
case PAUSE_ACTIVITY_FINISHING: {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "activityPause");
SomeArgs args = (SomeArgs) msg.obj;
handlePauseActivity((IBinder) args.arg1, true, (args.argi1 & USER_LEAVING) != 0,
args.argi2, (args.argi1 & DONT_REPORT) != 0, args.argi3);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
} break;
......
}
private void handlePauseActivity(IBinder token, boolean finished,
boolean userLeaving, int configChanges, boolean dontReport, int seq) {
......
performPauseActivity(token, finished, r.isPreHoneycomb(), "handlePauseActivity");
......
// Tell the activity manager we have paused.
if (!dontReport) {
try {
ActivityManager.getService().activityPaused(token);
} catch (RemoteException ex) {
throw ex.rethrowFromSystemServer();
}
}
mSomeActivitiesChanged = true;
}
}
final Bundle performPauseActivity(IBinder token, boolean finished,
boolean saveState, String reason) {
ActivityClientRecord r = mActivities.get(token);
return r != null ? performPauseActivity(r, finished, saveState, reason) : null;
}
final Bundle performPauseActivity(ActivityClientRecord r, boolean finished,
boolean saveState, String reason) {
if (r.paused) {
if (r.activity.mFinished) {
// If we are finishing, we won't call onResume() in certain cases.
// So here we likewise don't want to call onPause() if the activity
// isn't resumed.
return null;
}
RuntimeException e = new RuntimeException(
"Performing pause of activity that is not resumed: "
+ r.intent.getComponent().toShortString());
Slog.e(TAG, e.getMessage(), e);
}
if (finished) {
r.activity.mFinished = true;
}
// Next have the activity save its current state and managed dialogs...
if (!r.activity.mFinished && saveState) {
callCallActivityOnSaveInstanceState(r);
}
performPauseActivityIfNeeded(r, reason);
// Notify any outstanding on paused listeners
ArrayList<OnActivityPausedListener> listeners;
synchronized (mOnPauseListeners) {
listeners = mOnPauseListeners.remove(r.activity);
}
int size = (listeners != null ? listeners.size() : 0);
for (int i = 0; i < size; i++) {
listeners.get(i).onPaused(r.activity);
}
return !r.activity.mFinished && saveState ? r.state : null;
}
private void performPauseActivityIfNeeded(ActivityClientRecord r, String reason) {
if (r.paused) {
// You are already paused silly...
return;
}
try {
r.activity.mCalled = false;
mInstrumentation.callActivityOnPause(r.activity);
EventLog.writeEvent(LOG_AM_ON_PAUSE_CALLED, UserHandle.myUserId(),
r.activity.getComponentName().getClassName(), reason);
if (!r.activity.mCalled) {
throw new SuperNotCalledException("Activity " + safeToComponentShortString(r.intent)
+ " did not call through to super.onPause()");
}
} catch (SuperNotCalledException e) {
throw e;
} catch (Exception e) {
if (!mInstrumentation.onException(r.activity, e)) {
throw new RuntimeException("Unable to pause activity "
+ safeToComponentShortString(r.intent) + ": " + e.toString(), e);
}
}
r.paused = true;
}
再次進入Instrumentation中
/**
* Perform calling of an activity's {@link Activity#onPause} method. The
* default implementation simply calls through to that method.
*
* @param activity The activity being paused.
*/
public void callActivityOnPause(Activity activity) {
activity.performPause();
}
進入Activity的performPause中
final void performPause() {
mDoReportFullyDrawn = false;
//activity 暫停，關聯的fragment也pause，這裡就說明了為什麼fragment和activity的生命周期是綁定的
mFragments.dispatchPause();
mCalled = false;
// 調用onPause()暫停方法
onPause();
mResumed = false;
if (!mCalled && getApplicationInfo().targetSdkVersion
>= android.os.Build.VERSION_CODES.GINGERBREAD) {
throw new SuperNotCalledException(
"Activity " + mComponent.toShortString() +
" did not call through to super.onPause()");
}
mResumed = false;
}
可見，在啟動一個Activity的時候最先被執行的是棧頂的Activity的onPause方法
接下來我們回到代碼
ActivityManager.getService().activityPaused(token);
進入ActivityManagerService中的activityPaused()方法
@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);
}
進入ActivityStack中的activityPausedLocked()方法
final void activityPausedLocked(IBinder token, boolean timeout) {
......
try {
completePauseLocked(true /* resumeNext */, null /* resumingActivity */);
} finally {
mService.mWindowManager.continueSurfaceLayout();
}
return;
......
}
......
}
private void completePauseLocked(boolean resumeNext, ActivityRecord resuming) {
......
if (resumeNext) {
final ActivityStack topStack = mStackSupervisor.getFocusedStack();
if (!mService.isSleepingOrShuttingDownLocked()) {
mStackSupervisor.resumeFocusedStackTopActivityLocked(topStack, prev, null);
} rvisor.ensureActivitiesVisibleLocked(resuming, 0, !PRESERVE_WINDOWS);
}
進入ActivityStackSupervisor中的resumeFocusedStackTopActivityLocked()方法
boolean resumeFocusedStackTopActivityLocked(
ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {
......
if (targetStack != null && isFocusedStack(targetStack)) {
return targetStack.resumeTopActivityUncheckedLocked(target, targetOptions);
}
......
}
進入ActivityStack中的resumeTopActivityUncheckedLocked()方法
/**
* Ensure that the top activity in the stack is resumed.
*
* @param prev The previously resumed activity, for when in the process
* of pausing; can be null to call from elsewhere.
* @param options Activity options.
*
* @return Returns true if something is being resumed, or false if
* nothing happened.
*
* NOTE: It is not safe to call this method directly as it can cause an activity in a
* non-focused stack to be resumed.
* Use {@link ActivityStackSupervisor#resumeFocusedStackTopActivityLocked} to resume the
* right activity for the current system state.
*/
boolean resumeTopActivityUncheckedLocked(ActivityRecord prev, ActivityOptions options) {
if (mStackSupervisor.inResumeTopActivity) {
// Don't even start recursing.
return false;
}
boolean result = false;
try {
// Protect against recursion.
mStackSupervisor.inResumeTopActivity = true;
result = resumeTopActivityInnerLocked(prev, options);
} finally {
mStackSupervisor.inResumeTopActivity = false;
}
// When resuming the top activity, it may be necessary to pause the top activity (for
// example, returning to the lock screen. We suppress the normal pause logic in
// {@link #resumeTopActivityUncheckedLocked}, since the top activity is resumed at the end.
// We call the {@link ActivityStackSupervisor#checkReadyForSleepLocked} again here to ensure
// any necessary pause logic occurs.
mStackSupervisor.checkReadyForSleepLocked();
return result;
}
private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) {
......
mStackSupervisor.startSpecificActivityLocked(next, true, true);
......
}
進入ActivityStackSupervisor中的startSpecificActivityLocked()方法
private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) {
if (!mService.mBooting && !mService.mBooted) {
......
mStackSupervisor.startSpecificActivityLocked(next, true, true);
}
void startSpecificActivityLocked(ActivityRecord r,
boolean andResume, boolean checkConfig) {
......
realStartActivityLocked(r, app, andResume, checkConfig);
......
}
final boolean realStartActivityLocked(ActivityRecord r, ProcessRecord app,
boolean andResume, boolean checkConfig) throws RemoteException {
......
app.thread.scheduleLaunchActivity(new Intent(r.intent), r.appToken,
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, !andResume,
mService.isNextTransitionForward(), profilerInfo);
}
進入ApplicationThread中的scheduleLaunchActivity()方法
@Override
public final void scheduleLaunchActivity(Intent intent, IBinder token, int ident,
ActivityInfo info, Configuration curConfig, Configuration overrideConfig,
CompatibilityInfo compatInfo, String referrer, IVoiceInteractor voiceInteractor,
int procState, Bundle state, PersistableBundle persistentState,
List<ResultInfo> pendingResults, List<ReferrerIntent> pendingNewIntents,
boolean notResumed, boolean isForward, ProfilerInfo profilerInfo) {
updateProcessState(procState, false);
ActivityClientRecord r = new ActivityClientRecord();
r.token = token;
r.ident = ident;
r.intent = intent;
r.referrer = referrer;
r.voiceInteractor = voiceInteractor;
r.activityInfo = info;
r.compatInfo = compatInfo;
r.state = state;
r.persistentState = persistentState;
r.pendingResults = pendingResults;
r.pendingIntents = pendingNewIntents;
r.startsNotResumed = notResumed;
r.isForward = isForward;
r.profilerInfo = profilerInfo;
r.overrideConfig = overrideConfig;
updatePendingConfiguration(curConfig);
sendMessage(H.LAUNCH_ACTIVITY, r);
}
public void handleMessage(Message msg) {
if (DEBUG_MESSAGES) Slog.v(TAG, ">>> handling: " + codeToString(msg.what));
switch (msg.what) {
case LAUNCH_ACTIVITY: {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "activityStart");
final ActivityClientRecord r = (ActivityClientRecord) msg.obj;
r.packageInfo = getPackageInfoNoCheck(
r.activityInfo.applicationInfo, r.compatInfo);
handleLaunchActivity(r, null, "LAUNCH_ACTIVITY");
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
} break;
}
private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {
......
Activity a = performLaunchActivity(r, customIntent);
if (a != null) {
......
handleResumeActivity(r.token, false, r.isForward,
!r.activity.mFinished && !r.startsNotResumed, r.lastProcessedSeq, reason);
if (!r.activity.mFinished && r.startsNotResumed) {
// The activity manager actually wants this one to start out paused, because it
// needs to be visible but isn't in the foreground. We accomplish this by going
// through the normal startup (because activities expect to go through onResume()
// the first time they run, before their window is displayed), and then pausing it.
// However, in this case we do -not- need to do the full pause cycle (of freezing
// and such) because the activity manager assumes it can just retain the current
// state it has.
performPauseActivityIfNeeded(r, reason);
// We need to keep around the original state, in case we need to be created again.
// But we only do this for pre-Honeycomb apps, which always save their state when
// pausing, so we can not have them save their state when restarting from a paused
// state. For HC and later, we want to (and can) let the state be saved as the
// normal part of stopping the activity.
if (r.isPreHoneycomb()) {
r.state = oldState;
}
}
} else {
......
ActivityManager.getService()
.finishActivity(r.token, Activity.RESULT_CANCELED, null,
Activity.DONT_FINISH_TASK_WITH_ACTIVITY);
......
}
}
類的加載機制從這裡開始，ClassLoader開始加載這個activity
private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent) {
......
ContextImpl appContext = createBaseContextForActivity(r);
Activity activity = null;
try {
java.lang.ClassLoader cl = appContext.getClassLoader();
activity = mInstrumentation.newActivity(
cl, component.getClassName(), r.intent);
} catch (Exception e) {
}
try {
......
if (activity != null) {
......
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);
......
if (!r.activity.mFinished) {
activity.performStart();
r.stopped = false;
}
......
return activity;
}
來自網上：
** ActivityManagerService** 元件通信系統核心管理類 （ActivityManagerNative）IPC通信
** ActivityStackSupervisor** 管理整個手機的Activity任務棧
ActivityStack Activity棧（任務棧）
** PackageManagerService** 主要負責對系統的apk進行管理，不管是系統apk(/system/app)，還是我們手工安裝上去的，系統所有的apk都是由其管理的。
** ActivityThread** Activity的入口是onCreate方法，Android上一個應用的入口是ActivityThread。和普通的Java類一樣有一個main方法。用于控制與管理一個應用程序的主線程的操作，包括管理與處理activity manager發送過來的關于activities、廣播以及其他的操作請求
ActivityManagerService和ActivityStack位于同一個程序中，而ApplicationThread和ActivityThread位于另一個程序中。其中，ActivityManagerService是負責管理Activity的生命周期的，ActivityManagerService還借助ActivityStack是來把所有的Activity按照後進先出的順序放在一個堆棧中；對于每一個應用程式來說，都有一個ActivityThread來表示應用程式的主程序，而每一個ActivityThread都包含有一個ApplicationThread執行個體，它是一個Binder對象，負責和其它程序進行通信。