應(yīng)用內(nèi)啟動(dòng)Activity流程圖
1 Activity會(huì)執(zhí)行的startActivity有幾種重載方法伐谈，但最終會(huì)調(diào)用startActivityForResult
2 Activity 的startActivityForResult會(huì)調(diào)用Instrumentation的execStartActivity方法
Instrumentation.ActivityResult ar =
mInstrumentation.execStartActivity(
this, mMainThread.getApplicationThread(), mToken, this,
intent, requestCode, options);
3 Instrumentation的execStartActivity方法會(huì)調(diào)用 ActivityManagerNative的startActivity
int result = ActivityManagerNative.getDefault()
.startActivity(whoThread, who.getBasePackageName(), intent,
intent.resolveTypeIfNeeded(who.getContentResolver()),
token, target != null ? target.mEmbeddedID : null,
requestCode, 0, null, options);
ps:這個(gè)方法最后還會(huì)執(zhí)行
checkStartActivityResult來(lái)檢查是否啟動(dòng)成功溶弟。
4 ActivityManagerNative的gDefault會(huì)通過(guò)Binder返回ActivityManagerService的單例昔逗。實(shí)際上是調(diào)用的是ActivityManagerService的startActivity方法昧旨，會(huì)調(diào)用startActivityAsUser
startActivityAsUser(caller, callingPackage, intent, resolvedType, resultTo,
resultWho, requestCode, startFlags, profilerInfo, options,
UserHandle.getCallingUserId());
5 ActivityManagerService的` startActivityAsUser `會(huì)調(diào)用ActivityStackSupervisor的` startActivityMayWait `
mStackSupervisor.startActivityMayWait(caller, -1, callingPackage, intent,
resolvedType, null, null, resultTo, resultWho, requestCode, startFlags,
profilerInfo, null, null, options, userId, null, null);
6 ActivityStackSupervisor的startActivityMayWait會(huì)調(diào)用startActivityLocked
int res = startActivityLocked(caller, intent, resolvedType, aInfo,
voiceSession, voiceInteractor, resultTo, resultWho,
requestCode, callingPid, callingUid, callingPackage,
realCallingPid, realCallingUid, startFlags, options,
componentSpecified, null, container, inTask);
7 ActivityStackSupervisor的startActivityLocked會(huì)調(diào)用startActivityUncheckedLocked
err = startActivityUncheckedLocked(r, sourceRecord, voiceSession, voiceInteractor,
startFlags, true, options, inTask);
8 ActivityStackSupervisor的startActivityUncheckedLocked會(huì)調(diào)用ActivityStack的startActivityLocked
targetStack.startActivityLocked(r, newTask, doResume, keepCurTransition, options);
9 ActivityStack的startActivityLocked會(huì)ActivityStackSupervisor調(diào)用的resumeTopActivitiesLocked
mStackSupervisor.resumeTopActivitiesLocked(this, r, options);
10 ActivityStackSupervisor的resumeTopActivitiesLocked又會(huì)調(diào)用回ActivityStack的resumeTopActivityLocked
result = targetStack.resumeTopActivityLocked(target, targetOptions);
11 ActivityStack的resumeTopActivityLocked又會(huì)調(diào)用自身的resumeTopActivityInnerLocked
result = resumeTopActivityInnerLocked(prev, options);
12 ActivityStack的resumeTopActivityInnerLocked會(huì)調(diào)用自身的startPausingLocked先暫停之前的Activity
pausing |= startPausingLocked(userLeaving, false, true, dontWaitForPause);
PS： 這里會(huì)結(jié)束掉這個(gè)resumeTopActivityInnerLocked，返回true
if (pausing) {
if (DEBUG_SWITCH || DEBUG_STATES) Slog.v(TAG,
"resumeTopActivityLocked: Skip resume: need to start pausing");
// At this point we want to put the upcoming activity's process
// at the top of the LRU list, since we know we will be needing it
// very soon and it would be a waste to let it get killed if it
// happens to be sitting towards the end.
if (next.app != null && next.app.thread != null) {
mService.updateLruProcessLocked(next.app, true, null);
}
if (DEBUG_STACK) mStackSupervisor.validateTopActivitiesLocked();
return true;
}
13 ActivityStack的startPausingLocked會(huì)調(diào)用ActivityRecord的ProcessRecord
的IApplicationThread禽车，通過(guò)Binder實(shí)際上調(diào)用ActivityThread的ApplicationThread的schedulePauseActivity
prev.app.thread.schedulePauseActivity(prev.appToken, prev.finishing,
userLeaving, prev.configChangeFlags, dontWait);
14 ActivityThread的ApplicationThread的schedulePauseActivity發(fā)送消息最后會(huì)調(diào)用ActivityThread的handlePauseActivity,最后會(huì)調(diào)用ActivityManagerService的activityPaused
PS:performPauseActivity會(huì)調(diào)用Activity的onPause
ActivityManagerNative.getDefault().activityPaused(token);
15 ActivityManagerService的activityPaused會(huì)調(diào)用ActivityStack的activityPausedLocked
stack.activityPausedLocked(token, false);
16 用ActivityStack的activityPausedLocked會(huì)調(diào)用自身的completePauseLocked
completePauseLocked(true);
17 用ActivityStack的completePauseLocked又會(huì)調(diào)用ActivityStackSupervisor的resumeTopActivitiesLocked
mStackSupervisor.resumeTopActivitiesLocked(topStack, prev, null);
18 ActivityStackSupervisor的resumeTopActivitiesLocked又會(huì)調(diào)用回ActivityStack的resumeTopActivityLocked
result = targetStack.resumeTopActivityLocked(target, targetOptions);
19 ActivityStack的resumeTopActivityLocked又會(huì)調(diào)用自身的resumeTopActivityInnerLocked
result = resumeTopActivityInnerLocked(prev, options);
20 ActivityStack的resumeTopActivityInnerLocked會(huì)調(diào)用ActivityStackSupervisor的startSpecificActivityLocked
if (next.app != null && next.app.thread != null) {
...
}else{
mStackSupervisor.startSpecificActivityLocked(next, true, true);
}
21 ActivityStackSupervisor的startSpecificActivityLocked,因?yàn)閼?yīng)用程序已經(jīng)運(yùn)行艇搀，會(huì)調(diào)用ActivityStackSupervisor的realStartActivityLocked
// Is this activity's application already running?
ProcessRecord app = mService.getProcessRecordLocked(r.processName,
r.info.applicationInfo.uid, true);
r.task.stack.setLaunchTime(r);
if (app != null && app.thread != null) {
try {
if ((r.info.flags&ActivityInfo.FLAG_MULTIPROCESS) == 0
|| !"android".equals(r.info.packageName)) {
// Don't add this if it is a platform component that is marked
// to run in multiple processes, because this is actually
// part of the framework so doesn't make sense to track as a
// separate apk in the process.
app.addPackage(r.info.packageName, r.info.applicationInfo.versionCode,
mService.mProcessStats);
}
realStartActivityLocked(r, app, 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.
}
22 ActivityStackSupervisor的realStartActivityLocked會(huì)調(diào)用ActivityThread的ApplicationThread的scheduleLaunchActivity
app.thread.scheduleLaunchActivity(new Intent(r.intent), r.appToken,
System.identityHashCode(r), r.info, new Configuration(mService.mConfiguration),
r.compat, r.launchedFromPackage, r.task.voiceInteractor, app.repProcState,
r.icicle, r.persistentState, results, newIntents, !andResume,
23 ApplicationThread的scheduleLaunchActivity最終會(huì)調(diào)用ActivityThread的handleLaunchActivity
24 ActivityThread的handleLaunchActivity會(huì)調(diào)用自身的performLaunchActivity
Activity a = performLaunchActivity(r, customIntent);
25 ActivityThread的performLaunchActivity會(huì)調(diào)用Instrumentation的callActivityOnCreate
mInstrumentation.callActivityOnCreate(activity, r.state, r.persistentState);
26 Instrumentation的callActivityOnCreate會(huì)調(diào)用Activity的performCreate
activity.performCreate(icicle);
27 Activity的performCreate會(huì)調(diào)用自身的onCreate，至此Activity就onCreateonCreate(icicle);
總結(jié)
- 和Launcher啟動(dòng)應(yīng)用程序區(qū)別在于應(yīng)用已啟動(dòng)亲桦，在21步的時(shí)候崖蜜，不用新建PID和運(yùn)行ActivityThread，而是直接啟動(dòng)Activity客峭。
