Activity、Service、ContentProvider、BroadcastReceiver这四大组件，在启动的过程中，当其承载的进程不存在时需要调用startProcessLocked先创建进程。
下面以launcher activtity的启动流程为例
@frameworks/base/services/core/java/com/android/server/wm/ActivityStartController.javaService.getActivityStartController().startHomeActivity(homeIntent, aInfo, myReason, taskDisplayArea);
@frameworks/base/services/core/java/com/android/server/wm/ActivityStarter.javamLastHomeActivityStartResult = obtainStarter(intent, "startHomeActivity: " + reason).setActivityOptions(options.toBundle()).execute();res = executeRequest(mRequest);ActivityRecord r = new ActivityRecord.Builder(mService)..setActivityInfo(aInfo)mLastStartActivityResult = startActivityUnchecked(r, sourceRecord, voiceSession,result = startActivityInner(r, sourceRecord, voiceSession, voiceInteractor,startFlags, doResume, options, inTask, inTaskFragment, restrictedBgActivity,mTargetRootTask.startActivityLocked(mStartActivity,
@frameworks/base/services/core/java/com/android/server/wm/RootWindowContainer.javamRootWindowContainer.resumeFocusedTasksTopActivities(mTargetRootTask, mStartActivity, mOptions, mTransientLaunch);final Task focusedRoot = display.getFocusedRootTask();
@frameworks/base/services/core/java/com/android/server/wm/Task.javafocusedRoot.resumeTopActivityUncheckedLocked(target, targetOptions);someActivityResumed = resumeTopActivityInnerLocked(prev, options, deferPause);
@frameworks/base/services/core/java/com/android/server/wm/TaskFragment.javaresumed[0] = topFragment.resumeTopActivity(prev, options, deferPause);ActivityRecord next = topRunningActivity(true /* focusableOnly */);pausing |= startPausing(mTaskSupervisor.mUserLeaving, false /* uiSleeping */, next, "resumeTopActivity"); //这里就是stop上一个activity的地方if (next.attachedToProcess()) { //要启动的activity所在的进程已经起来了，直接通过事务的形式去启动activityfinal ClientTransaction transaction = ClientTransaction.obtain(next.app.getThread(), next.appToken);mAtmService.getLifecycleManager().scheduleTransaction(transaction);} else { //如果进程没启动，调用ActivityTaskSupervisor的startSpecificActivity
@frameworks/base/services/core/java/com/android/server/wm/ActivityTaskSupervisor.javamTaskSupervisor.startSpecificActivity(next, true, true);
@base/services/core/java/com/android/server/wm/ActivityTaskManagerService.javamService.startProcessAsync(r, knownToBeDead, isTop, isTop ? "top-activity" : "activity");final Message m = PooledLambda.obtainMessage(ActivityManagerInternal::startProcess, mAmInternal, activity.processName,mH.sendMessage(m);LocalService::startProcess //class LocalService extends ActivityManagerInternalstartProcessLocked(processName, info, knownToBeDead, 0 /* intentFlags */, new HostingRecord(hostingType, hostingName, isTop),
@frameworks/base/services/core/java/com/android/server/am/ProcessList.javareturn mProcessList.startProcessLocked(processName, info, knownToBeDead, intentFlags,startProcessLocked(app, hostingRecord, zygotePolicyFlags, abiOverride);startProcessLocked(app, hostingRecord, zygotePolicyFlags, falsestartProcessLocked(hostingRecord, entryPoint, app, uid, gids, runtimeFlags, zygotePolicyFlags, mountExternal, seInfo, requiredAbi,mService.mProcStartHandler.post(() -> handleProcessStart( app,handleProcessStartedLocked(app, startResult, startSeq);return handleProcessStartedLocked(pending, startResult.pid, startResult.usingWrapper,buf.append("Start proc "); //Start proc 1486:com.android.launcher/1000 for top-activity {com.android.launcher/com.android.launcher.MainActivity}buf.append(pid);buf.append(':');buf.append(app.processName);buf.append('/');buf.append(app.getHostingRecord().getType());buf.append(app.getHostingRecord().getName());..............
@src/main/java/com/dynabook/launcher/MainActivity.javaMainActivity::onCreate @frameworks/base/services/core/java/com/android/server/wm/ActivityStartController.java
Service.getActivityStartController().startHomeActivity(homeIntent, aInfo, myReason, taskDisplayArea);
@frameworks/base/services/core/java/com/android/server/wm/ActivityStarter.java
mLastHomeActivityStartResult = obtainStarter(intent, "startHomeActivity: " + reason).setActivityOptions(options.toBundle()).execute();
res = executeRequest(mRequest);
ActivityRecord r = new ActivityRecord.Builder(mService)..setActivityInfo(aInfo)
mLastStartActivityResult = startActivityUnchecked(r, sourceRecord, voiceSession,
result = startActivityInner(r, sourceRecord, voiceSession, voiceInteractor,startFlags, doResume, options, inTask, inTaskFragment, restrictedBgActivity,
mTargetRootTask.startActivityLocked(mStartActivity,
@frameworks/base/services/core/java/com/android/server/wm/RootWindowContainer.java
mRootWindowContainer.resumeFocusedTasksTopActivities(mTargetRootTask, mStartActivity, mOptions, mTransientLaunch);
final Task focusedRoot = display.getFocusedRootTask();
@frameworks/base/services/core/java/com/android/server/wm/Task.java
focusedRoot.resumeTopActivityUncheckedLocked(target, targetOptions);
someActivityResumed = resumeTopActivityInnerLocked(prev, options, deferPause);
@frameworks/base/services/core/java/com/android/server/wm/TaskFragment.java
resumed[0] = topFragment.resumeTopActivity(prev, options, deferPause);
ActivityRecord next = topRunningActivity(true /* focusableOnly */);
pausing |= startPausing(mTaskSupervisor.mUserLeaving, false /* uiSleeping */, next, "resumeTopActivity"); //这里就是stop上一个activity的地方
if (next.attachedToProcess()) { //要启动的activity所在的进程已经起来了，直接通过事务的形式去启动activity
final ClientTransaction transaction = ClientTransaction.obtain(next.app.getThread(), next.appToken);
mAtmService.getLifecycleManager().scheduleTransaction(transaction);
} else { //如果进程没启动，调用ActivityTaskSupervisor的startSpecificActivity
@frameworks/base/services/core/java/com/android/server/wm/ActivityTaskSupervisor.java
mTaskSupervisor.startSpecificActivity(next, true, true);
@base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
mService.startProcessAsync(r, knownToBeDead, isTop, isTop ? "top-activity" : "activity");
final Message m = PooledLambda.obtainMessage(ActivityManagerInternal::startProcess, mAmInternal, activity.processName,
mH.sendMessage(m);
LocalService::startProcess //class LocalService extends ActivityManagerInternal
startProcessLocked(processName, info, knownToBeDead, 0 /* intentFlags */, new HostingRecord(hostingType, hostingName, isTop),
@frameworks/base/services/core/java/com/android/server/am/ProcessList.java
return mProcessList.startProcessLocked(processName, info, knownToBeDead, intentFlags,
startProcessLocked(app, hostingRecord, zygotePolicyFlags, abiOverride);
startProcessLocked(app, hostingRecord, zygotePolicyFlags, false
startProcessLocked(hostingRecord, entryPoint, app, uid, gids, runtimeFlags, zygotePolicyFlags, mountExternal, seInfo, requiredAbi,
mService.mProcStartHandler.post(() -> handleProcessStart( app,
handleProcessStartedLocked(app, startResult, startSeq);
return handleProcessStartedLocked(pending, startResult.pid, startResult.usingWrapper,
buf.append("Start proc "); //Start proc 1486:com.android.launcher/1000 for top-activity {com.android.launcher/com.android.launcher.MainActivity}
buf.append(pid);
buf.append(':');
buf.append(app.processName);
buf.append('/');
buf.append(app.getHostingRecord().getType());
buf.append(app.getHostingRecord().getName());
..............
@src/main/java/com/dynabook/launcher/MainActivity.java
MainActivity::onCreate
