Android相關(guān)流程圖

init:

1. 掛載和創(chuàng)建系統(tǒng)文件
2. 解析rc文件
3. 進(jìn)入無限循環(huán)
   1. 執(zhí)行action -- zygote啟動
   2. 檢測并重啟進(jìn)程
   3. 接收子進(jìn)程的SIGCHLD信號，執(zhí)行響應(yīng)的方法

zygote：

1. native
   1. 初始化Android運行環(huán)境
   2. 注冊jni
   3. 執(zhí)行ZygoteInit.main 方法 進(jìn)入Java層
2. Java
   1. 創(chuàng)建 socket
   2. 執(zhí)行預(yù)加載
   3. 通過fork創(chuàng)建 SystemServer 進(jìn)程
   4. 進(jìn)入循環(huán)：等待AMS的通知，創(chuàng)建對應(yīng)的進(jìn)程

SystemServer
nice-name 給進(jìn)程的名稱

pid = Zygote.forkSystemServer

//啟動 SystemServer.main
return handleSystemServerProcess(parsedArgs);
    //開啟Binder線程池
    ZygoteInit.nativeZygoteInit();
        gCurRuntime->onZygoteInit();
             sp<ProcessState> proc = ProcessState::self();
                proc->startThreadPool();
    // 運行 SystemServer.main
    RuntimeInit.applicationInit
        // 通過反射執(zhí)行 SystemServer.main
        mMethod.invoke(null, new Object[] { mArgs }); 

SystemServer進(jìn)程:

1. createSystemContext();
   //執(zhí)行systemMain()@ActivityThread,在systemMain方法中

   1. new ActivityThread()兼丰，執(zhí)行attach()@ActivityThread
      //在attach方法中
   2. new Instrumentation(),
   3. ContextImpl context = ContextImpl.createAppContext(
      this, getSystemContext().mPackageInfo);
   4. Application mInitialApplication = context.mPackageInfo.makeApplication(true, null);

2. mSystemServiceManager = new SystemServiceManager(mSystemContext); // 系統(tǒng)服務(wù)

   1. startService --> service.onStart(); // 繼承自 SystemService 的服務(wù)

3. startBootstrapServices(t); // 引導(dǎo)服務(wù) --AMS
   //android 10開始 多了個 ATMS(ActivityTaskManagerService)

   1. mService = new ActivityTaskManagerService(context);

      mService.start();

       ServiceManager.addService(name, service,resumeTopActivityInnerLocked allowIsolated, dumpPriority);
      

   2. 創(chuàng)建 AMS -- 其他三個服務(wù)尖阔，持有 ATMS
      mService = new ActivityManagerService(context, sAtm);

      mService.start();

4. startCoreServices(t); // 核心服務(wù)

5. startOtherServices(t); // 其他服務(wù) -- WMS

   mActivityManagerService.systemReady // 啟動Launcher

   startSystemUi(context, windowManagerF); // 啟動 SystemUI

mActivityManagerService.systemReady -->

mActivityTaskManager.onSystemReady@ActivityTaskManagerService -->

mAtmInternal.resumeTopActivities@ActivityTaskManagerService -->

mRootWindowContainer.resumeFocusedStacksTopActivities()@RootWindowContainer -->

resumeFocusedStacksTopActivities@RootWindowContainer -->

targetStack.resumeTopActivityUncheckedLocked@ActivityStack

--> resumeTopActivityInnerLocked@ActivityStack -->

resumeNextFocusableActivityWhenStackIsEmpty@ActivityStack

--> mRootWindowContainer.resumeHomeActivity@RootWindowContainer -->

startHomeOnTaskDisplayArea@RootWindowContainer -->

resolveHomeActivity@RootWindowContainer -->

mService.getActivityStartController().startHomeActivity@ActivityStartController obtainStarter@ActivityStartController -->

execute@ActivityStarter -->

executeRequest@ActivityStarter -->

startActivityInner@ActivityStarter

這里調(diào)用了startActivity()方法來啟動Launcher春贸，最終會進(jìn)入Launcher的onCreate()方法，Launcher啟動完成。

mSystemServiceManager.startBootPhase // 狀態(tài)設(shè)置

SystemServiceManager:管理服務(wù)的生命周期

ServerManager：管理Binder服務(wù)的

ServiceManager.getService(Context.ACTIVITY_TASK_SERVICE);

publishBinderService(Context.ACTIVITY_TASK_SERVICE, mService);

ServiceManager.addService(name, service, allowIsolated, dumpPriority); // 注冊Binder服務(wù)

Activity啟動流程：

startActivity@Activity --> startActivityForResult@Activity

--> mInstrumentation.execStartActivity@Instrumentation -->

ActivityTaskManager.getService().startActivity@ActivityTaskManagerService

--> startActivityAsUser@ActivityTaskManagerService

--> execute@ActivityStarter -->

executeRequest@ActivityStarter -->

startActivityUnchecked@ActivityStarter -->

startActivityInner@ActivityStarter -->

resumeFocusedStacksTopActivities@RootWindowContainer -->

resumeTopActivityUncheckedLocked@ActivityStack -->

resumeTopActivityInnerLocked@ActivityStack -->

startSpecificActivity@ActivityStackSupervisor -->

realStartActivityLocked@ActivityStackSupervisor -->

scheduleTransaction@ClientLifecycleManager -->

schedule@ClientTransaction -->

scheduleTransaction@ApplicationThread -->

scheduleTransaction@Activity -->

execute@TransactionExecutor -->

executeCallbacks@TransactionExecutor -->

execute@LaunchActivityItem -->

handleLaunchActivity@ActivityThread -->

performLaunchActivity@ActivityThread -->

createBaseContextForActivity@ActivityThread 、mInstrumentation.newActivity此疹、makeApplication@LoadApk -->

attach@Activity、callActivityOnCreate@Instrumentation -->

onCreate@Activity

小結(jié)

1. 調(diào)用從system_server進(jìn)程傳過來的ClientTransaction.CallBack類中的execute方法遮婶，其繼續(xù)調(diào)用ActivityThread.handleLaunchActivity方法來啟動Activity蝗碎。
2. ActivityThread.handleLaunchActivity調(diào)用performLaunchActivity方法啟動Activity
3. performLaunchActivity先獲取啟動Activity的ActivityInfo，而后創(chuàng)建一個LoadedApk和上下文ContextImpl旗扑。在通過反射去創(chuàng)建此Activity對象蹦骑，并執(zhí)行Activity的onCreate方法。

SystemServer執(zhí)行流程圖：

image.png

Activity啟動：

image.png

Android 啟動流程時序圖：

image.png

Activity生命周期管理類圖：

image.png

下圖是ATMS處理startActivity過程臀防，并回調(diào)啟動進(jìn)程的ApplicationThread:

22650779-eabf22046e2f33d4.png

下圖為Android 30 之后眠菇，ActivityThread啟動Activity過程的時序圖：

22650779-72d2d3d9acda317d.png