用到的代码文件
frameworks/base/core/java/android/app/ApplicationThreadNative.java
frameworks/base/core/java/android/app/ActivityThread.java
frameworks/base/core/java/android/app/Instrumentation.java
frameworks/base/core/java/android/app/Activity.java
代称执行流程图
android activity启动流程
下面的代码是以android N（api 24）为基础。
当ApplicationThreadProxy类的schedulePauseActivity方法通过Binder通信方式发送消息后，ApplicationThreadNative类的onTransact()方法接收到消息。
下面是ApplicationThreadNative类中onTransact()方法内容。
@Override
public boolean onTransact(int code, Parcel data, Parcel reply, int flags)
throws RemoteException {
switch (code) {
case SCHEDULE_PAUSE_ACTIVITY_TRANSACTION:
{
android.util.Log.d(MTAG,
"onTransact: case SCHEDULE_PAUSE_ACTIVITY_TRANSACTION");
data.enforceInterface(IApplicationThread.descriptor);
IBinder b = data.readStrongBinder();
boolean finished = data.readInt() != 0;
boolean userLeaving = data.readInt() != 0;
int configChanges = data.readInt();
boolean dontReport = data.readInt() != 0;
/*
* 这个是定义在IApplicationThread接口中的抽象方法。
*/
schedulePauseActivity(b, finished, userLeaving,
configChanges, dontReport);
return true;
}
......
}
....
}
ApplicationThread继承自ApplicationThreadNative类。
ApplicationThread是定义在ActivityThread中的内部类。
下面schedulePauseActivity()方法即是对该抽象方法的具体实现。
public final void schedulePauseActivity(IBinder token, boolean finished,
boolean userLeaving, int configChanges, boolean dontReport) {
log("method called schedulePauseActivity();");
int seq = getLifecycleSeq();
log("pauseActivity " + ActivityThread.this
+ " operation received seq: " + seq);
/*pauseActivity android.app.ActivityThread@
a9813eb operation received seq: 0*/
/*
* 构造一个消息，具体是在类H中进行处理。
*/
sendMessage(
finished ? H.PAUSE_ACTIVITY_FINISHING : H.PAUSE_ACTIVITY,
token,
(userLeaving ? USER_LEAVING : 0)
| (dontReport ? DONT_REPORT : 0),
configChanges,
seq);
}
class H extends Handler{},下面是handleMessage()方法的具体内容。
public void handleMessage(Message msg) {
switch (msg.what) {
......
case PAUSE_ACTIVITY: {
log("handler case PAUSE_ACTIVITY");
Trace.traceBegin(
Trace.TRACE_TAG_ACTIVITY_MANAGER, "activityPause");
SomeArgs args = (SomeArgs) msg.obj;
//执行该方法
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;
......
}
}
接下来调用ActivityThread类中的handlePauseActivity()方法，下面是具体内容。
private void handlePauseActivity(IBinder token, boolean finished,
boolean userLeaving, int configChanges,
boolean dontReport, int seq) {
log("method called handlePauseActivity()");
log("token: "+token);//token: android.os.BinderProxy@17acb46
log("finished: "+finished);//finished: false
log("userLeaving: "+userLeaving);//true
log("configChanges: "+configChanges);//0
log("dontReport: "+dontReport);//false
log("seq: "+seq);//0
ActivityClientRecord r = mActivities.get(token);
/*ActivityRecord{dc3591d token=android.os.BinderProxy@6e1452f
{com.tct.launcher/com.tct.launcher.Launcher}}*/
log("ActivityClientRecord r: "+r);
if (DEBUG_ORDER)
Slog.d(TAG, "handlePauseActivity " + r + ", seq: " + seq);
if (!checkAndUpdateLifecycleSeq(seq, r, "pauseActivity")) {
return;
}
if (r != null) {
//Slog.v(TAG, "userLeaving=" + userLeaving
// + " handling pause of " + r);
if (userLeaving) {
performUserLeavingActivity(r);
}
r.activity.mConfigChangeFlags |= configChanges;
//进入这个方法
performPauseActivity(token, finished, r.isPreHoneycomb(),
"handlePauseActivity");
// Make sure any pending writes are now committed.
if (r.isPreHoneycomb()) {
QueuedWork.waitToFinish();
}
// Tell the activity manager we have paused.
if (!dontReport) {
try {
// android.app.ActivityManagerProxy
ActivityManagerNative.getDefault().activityPaused(token);
} catch (RemoteException ex) {
throw ex.rethrowFromSystemServer();
}
}
mSomeActivitiesChanged = true;
}
}
接下来调用ActivityThread类中的performPauseActivity()方法。
final Bundle performPauseActivity(IBinder token,
boolean finished,
boolean saveState, String reason) {
ActivityClientRecord r = mActivities.get(token);
//调用其重载方法
return r != null
? performPauseActivity(r, finished, saveState, reason) : null;
}
下面进入performPauseActivity()这个重载方法的执行流程。
final Bundle performPauseActivity(ActivityClientRecord r,
boolean finished,
boolean saveState, String reason) {
log("method called performPauseActivity()");
/*ActivityRecord{dc3591d
token=android.os.BinderProxy@6e1452f
{com.tct.launcher/com.tct.launcher.Launcher}}*/
log("ActivityClientRecord r : " + r);
log("finished : " + finished);//false
log("saveState : " + saveState);//false
log("reason: " + reason);//handlePauseActivity
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;
}
//// com.tct.launcher.Launcher
log("r.activity: " + r.activity.getClass().getName());
// Next have the activity save its current state
// and managed dialogs...
if (!r.activity.mFinished && saveState) {
callCallActivityOnSaveInstanceState(r);
}
/*
* 进入这里
*/
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;
}
下面进入ActivityThread类中的performPauseActivityIfNeeded()方法。
instrumentation n. 使用仪器, 乐器化, 仪表化, 指令
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;
}
下面调用Instrumentation类中的callActivityOnPause()方法。
/**
* 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) {
//调用了Activity自身的performPause方法
activity.performPause();
}
下面是Activity类中performPause()方法的具体内容。
final void performPause() {
mDoReportFullyDrawn = false;
mFragments.dispatchPause();
mCalled = false;
/**
* 找到了一个生命周期方法onPause()
* 表明我们在启动一个Activity的时候最先
* 被执行的是当前的Activity的onPause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;
}
在ActivityThread类的handlePauseActivity()方法中执行完performPauseActivity()方法后将会进入下面的流程。
private void handlePauseActivity(IBinder token,
boolean finished,boolean userLeaving,
int configChanges, boolean dontReport,
int seq) {
......
//这步暂停指定Activity已经结束了。
performPauseActivity(token,
finished, r.isPreHoneycomb(), "handlePauseActivity");
......
// Tell the activity manager we have paused.
if (!dontReport) {// dontReport -> false
try {
/**
* 关键的是这里，继续往下追踪。
*/
////android.app.ActivityManagerProxy
ActivityManagerNative.getDefault().activityPaused(token);
} catch (RemoteException ex) {
throw ex.rethrowFromSystemServer();
}
}
mSomeActivitiesChanged = true;
}
}
ActivityManagerProxy类是定义在ActivityManagerNative中的一个内部类。
下面是ActivityManagerProxy类中activityPaused()方法的具体实现。
public void activityPaused(IBinder token) throws RemoteException
{
Parcel data = Parcel.obtain();
Parcel reply = Parcel.obtain();
data.writeInterfaceToken(IActivityManager.descriptor);
data.writeStrongBinder(token);
mRemote.transact(ACTIVITY_PAUSED_TRANSACTION, data, reply, 0);
reply.readException();
data.recycle();
reply.recycle();
}
又调用Binder了，又进行进程间通信了......
本文由 tuzhao 创作，采用 知识共享署名4.0 国际许可协议进行许可
本站文章除注明转载/出处外，均为本站原创或翻译，转载前请务必署名
最后编辑时间为:
2017/12/05 13:43