Android 10 SystemServer服务中启动SystemUi中SystemUIService服务

代码路径：
frameworks/base/servicesjava/com/android/server/SystemServer.java
1、SystemServer.java文件中的main方法是在通过zygote中调用该方法

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

2、在SystemServer.java文件中.run()方法中调用startOtherServices(),该方法中就是来启动SystemUIService服务

private void run() {
   // Start services.
try {
    traceBeginAndSlog("StartServices");
    startBootstrapServices();
    startCoreServices();
    startOtherServices();
    SystemServerInitThreadPool.shutdown();
} catch (Throwable ex) {
    Slog.e("System", "******************************************");
    Slog.e("System", "************ Failure starting system services", ex);
    throw ex;
} finally {
    traceEnd();
}
}

3、在SystemServer.java文件中startSystemUi()方法就是拉起SystemUI中SystemUIService服务

private void startOtherServices() {
    traceBeginAndSlog("StartSystemUI");
try {
    startSystemUi(context, windowManagerF);
} catch (Throwable e) {
    reportWtf("starting System UI", e);
}
traceEnd();
}
private static void startSystemUi(Context context, WindowManagerService windowManager) {
    Intent intent = new Intent();
    intent.setComponent(new ComponentName("com.android.systemui",
            "com.android.systemui.SystemUIService"));
    intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);
    context.startServiceAsUser(intent, UserHandle.SYSTEM);
    windowManager.onSystemUiStarted();
}