SystemServer.java

• 类中方法执行

类中方法执行

  在这个类中有main()方法，这个类从main（）方法开始执行。

• main():

public static void main(String[] args){
    new SystemServer().run();
}

  在main（）方法中去生成一个SystemServer对象，并执行这个对象的run（）方法。

public SystemServer(){
    //省略代码;
}

• run():

private void run(){
    //省略代码;
    Looper.prepareMainLooper();
    //加载native服务;
    System.loadLibrary("android_servers");
    //检测上次是否成功关机;
    performPendingShutdown();
    //生成Context，初始化系统上下文，其实是生成一个ContextImpl对象;
    createSystemContext();
    //生成一个SystemServiceManager对象，并把它添加到LocalServices中，其中mSystemContext参数就是通过createSystemContext()方法来生成的;
    mSystemServiceManager = new SystemServiceManager(mSystemContext);
    mSystemServiceManager.setRuntimeRestarted(mRuntimeRestart);
    LocalServices.addService(SystemServiceManager.class,mSystemServiceManager);
    //使用单例模式生成SystemServerInitThreadPool线程池对象;
    SystemServerInitThreadPool.get();
    
    //---;
    //启动一些服务;
    //启动引导服务;
    startBootstarpServices();
    //启动核心服务;
    startCoreServices();
    //启动其他服务;
    startOtherServices();
    SystemServerInitThreadPool.shutdown();
    //---;
    //开始消息循环;
    Looper.loop();
}

• startBootstrapService():

private void startBootstrapService(){
    //---;
    //创建SystemConfig，进行权限的获取;
    SystemServerInitThreadPool.get().submit(SystemConfig::getInstance,TAG_SYSTEM_CONFIG);
    //启动Installer安装器服务;
    Installer installer = mSystemServiceManager.startService(Installer.class);
    //开启设备识别器服务;
    mSystemServiceManager.startService(DeviceIdentifiersPolicyService.class);
    //启动并初始化ActivityManagerService，Installer服务赋值给AMS;
        mActivityManagerService = mSystemServiceManager.startService(ActivityManagerService.lifecycle.class).getService();
        mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
    mActivityManagerService.setInstaller(installer);
    //启动PowerManagerService电量管理服务;
    mPowerManagerService = mSystemServiceManager.startService(PowerManagerService.class);
    //初始化电量管理器;
    mActivityManagerService.initPowerManagement();
    //---;
    //启动RecoverySystem服务;
    mSystemServiceManager.startService(RecoverySystemService.class);
    //标记裸机已经启动完了，如果我们困在运行时的重启循环中，这个标记可以跳出循环;
    RescueParty.noteBoot(mSystemContext);
    //启动灯光服务，包括背景亮度、闪光灯等;
    mSystemServiceManager.startService(LightService.class);
    //启动显示服务，用来显示UI;
    mDisplayManagerService = mSystemServiceManager.startService(DisplayManagerService.class);
    //开始开机动画;
    mSystemServiceManager.startBootPhase(SystemService.PHASE_WAIT_FOR_DEFAULT_DISPLAY);
    //加密模式下，只运行内核应用，此处先设置标志位;
    String cryptState = SystemProperties.get("vold.decrypt");
    if (ENCRYPTING_STATE.equals(cryptState)) {
         mOnlyCore = true;
    } else if (ENCRYPTED_STATE.equals(cryptState)) {
        mOnlyCore = true;
    }
    //---;
    //获取包管理器;
    mPackageManagerService = PackageManagerService.main(mSystemContext,installer,mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF,mOnlyCore);
    //---;
    //启动用户管理服务;
    mSystemServiceManager.startService(UserManagerService.LifeCycle.class);
    //从系统包中初始化属性资源;
    AttributeCache.init(mSystemContext);
    //设置系统进程;
    mActivityManagerService.setSystemProcess();
    //设置ui的调整策略;
    mDisplayManagerService.setupSchedulerPolicies();
    //启动OverlayManagerService;
    mSystemServiceManager.startService(new OverManagerService(mSystemContext,installer));
    //启动传感器服务;
    mSersorServiceStart = SystemServerInitThreadPool.get().submit(() -> {
        BootTimingsTraceLog traceLog = new BootTimingsTraceLog(
                SYSTEM_SERVER_TIMING_ASYNC_TAG, Trace.TRACE_TAG_SYSTEM_SERVER);
        traceLog.traceBegin(START_SENSOR_SERVICE);
    startSensorService();
}

• startCoreServices():

private void startCoreService(){
    //启动DropBox服务，用来记录系统日志;
    mSystemServiceManager.startService(DropBoxManagerService.class);
    //启动电池服务;
    mSystemServiceManager.startService(BatteryService.class);
    //启动使用状态服务;
    mSystemServiceManager.startService(UsageStateService.class);
    mActivityManagerService.setUsageStatsManager(LocalServices.getService(UsageStatsManagerInternal.class));
    //启动WebView更新服务;
    mWebViewUpdateService = mSystemServiceManager.startService(WebViewUpdateService.class);
}

• startOtherServices():

private void startOtherServices(){
    //在这个方法里也启动了好多其他的服务，这个方法代码一千多行，暂时不分析;
}

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