int do_class_start(int nargs, char **args)
{service_for_each_class(args[1], service_start_if_not_disabled);return 0;
}

void service_for_each_class(const char *classname,void (*func)(struct service *svc))
{……
}static void service_start_if_not_disabled(struct service *svc)
{if (!(svc->flags & SVC_DISABLED)) {service_start(svc, NULL);}
}

int main(){

　　　　　//挂在文件

//解析配置文件：init.rc……

//初始化化action queue

　　　　 ……for(;;){execute_one_command();restart_processes();for (i = 0; i < fd_count; i++) {if (ufds[i].revents == POLLIN) {if (ufds[i].fd == get_property_set_fd())handle_property_set_fd();else if (ufds[i].fd == get_keychord_fd())handle_keychord();else if (ufds[i].fd == get_signal_fd())handle_signal();}}}
}

service servicemanager /system/bin/servicemanagerclass coreuser systemgroup systemcriticalonrestart restart zygoteonrestart restart mediaonrestart restart surfaceflingeronrestart restart drm

service zygote /system/bin/app_process -Xzygote /system/bin --zygote --start-system-serverclass mainsocket zygote stream 666onrestart write /sys/android_power/request_state wakeonrestart write /sys/power/state ononrestart restart mediaonrestart restart netd参数：--zygote --start-system-server

int main( ){AppRuntime runtime;if (zygote) {runtime.start("com.android.internal.os.ZygoteInit",startSystemServer ? "start-system-server" : "");}
}class AppRuntime : public AndroidRuntime{}；

void start(const char* className, const char* options){// start the virtual machine Java在虚拟机中运行的JNIEnv* env;if (startVm(&mJavaVM, &env) != 0) {return;}//向刚刚新建的虚拟机注册JNI本地接口if (startReg(env) < 0) {return;}// jni 调用 java 方法，获取对应类的静态main方法jmethodID startMeth = env->GetStaticMethodID(startClass,"main","([Ljava/lang/String;)V");// jni调用 java方法，调用到ZygoteInit类的main函数
jclass startClass = env->FindClass(className);env->CallStaticVoidMethod(startClass, startMeth, strArray);
}

public static void main(String argv[]) {//Registers a server socket for zygote command connectionsregisterZygoteSocket();//Loads and initializes commonly used classes and//used resources that can be shared across processespreload();// Do an initial gc to clean up after startupgc();if (argv[1].equals("start-system-server")) {startSystemServer();}/*** Runs the zygote process's select loop. Accepts new connections as* they happen, and reads commands from connections one spawn-request's* worth at a time.*/runSelectLoopMode();    //loop中/*** Close and clean up zygote sockets. Called on shutdown and on the* child's exit path.*/closeServerSocket();
}

private static boolean startSystemServer(){/* Request to fork the system server process 孵化新的进程 */ZygoteConnection.Arguments parsedArgs = null;pid = Zygote.forkSystemServer(parsedArgs.uid, parsedArgs.gid,parsedArgs.gids,parsedArgs.debugFlags,null,parsedArgs.permittedCapabilities,parsedArgs.effectiveCapabilities);/* For child process 对新的子进程设置 */if (pid == 0) {handleSystemServerProcess(parsedArgs);}
}void handleSystemServerProcess(parsedArgs){closeServerSocket();//"system_server"Process.setArgV0(parsedArgs.niceName);//Pass the remaining arguments to SystemServer.RuntimeInit.zygoteInit(parsedArgs.targetSdkVersion,parsedArgs.remainingArgs);/* should never reach here */
}

//The main function called when started through the zygote process.
void zygoteInit(int targetSdkVersion, String[] argv){applicationInit(targetSdkVersion, argv);
}void applicationInit(int targetSdkVersion, String[] argv){// Remaining arguments are passed to the start class's static maininvokeStaticMain(args.startClass, args.startArgs);
}void invokeStaticMain(String className, String[] argv){Class<?> cl;cl = Class.forName(className);//获取SystemServer的main方法，抛出MethodAndArgsCaller异常Method m;m = cl.getMethod("main", new Class[] { String[].class });int modifiers = m.getModifiers();throw new ZygoteInit.MethodAndArgsCaller(m, argv);
}

public static void main(String argv[]) {try {……if (argv[1].equals("start-system-server")) {startSystemServer();       //这里如果抛出异常，跳过下面流程}runSelectLoopMode();    //loop中……} catch (MethodAndArgsCaller caller) {caller.run();        //处理的异常}
}

public static void main(String[] args) {System.loadLibrary("android_servers");    /** This method is called from Zygote to initialize the system.* This will cause the native services (SurfaceFlinger, AudioFlinger, etc..)* to be started. After that it will call back* up into init2() to start the Android services.*/init1(args);    //native 完了回调init2( )}//init1:frameworks/base/services/jni/com_android_server_SystemServer.cpp:: android_server_SystemServer_init1( ) 　　中调用：system_init
extern "C" status_t system_init()
{sp<ProcessState> proc(ProcessState::self());sp<IServiceManager> sm = defaultServiceManager();//启动SurfaceFlinger 和传感器property_get("system_init.startsurfaceflinger", propBuf, "1");SurfaceFlinger::instantiate();property_get("system_init.startsensorservice", propBuf, "1");SensorService::instantiate();// And now start the Android runtime.  We have to do this bit// of nastiness because the Android runtime initialization requires// some of the core system services to already be started.// All other servers should just start the Android runtime at// the beginning of their processes's main(), before calling// the init function.AndroidRuntime* runtime = AndroidRuntime::getRuntime();//回调 com.android.server.SystemServer init2 方法
JNIEnv* env = runtime->getJNIEnv();jclass clazz = env->FindClass("com/android/server/SystemServer");jmethodID methodId = env->GetStaticMethodID(clazz, "init2", "()V");env->CallStaticVoidMethod(clazz, methodId);//启动线程池 做为binder 服务ProcessState::self()->startThreadPool();IPCThreadState::self()->joinThreadPool();return NO_ERROR;}

public static final void init2() {   //建立线程来处理Thread thr = new ServerThread();      thr.setName("android.server.ServerThread");thr.start();
}//看看线程ServerThread里面都做了什么事情？
public void run() {addBootEvent(new String("Android:SysServerInit_START"));Looper.prepare();android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_FOREGROUND);//初始化服务，创建各种服务实例，如：电源、网络、Wifi、蓝牙，USB等，
　　//初始化完成以后加入到 ServiceManager中，//事我们用 Context.getSystemService (String name) 才获取到相应的服务PowerManagerService power = null;NetworkManagementService networkManagement = null;WifiP2pService wifiP2p = null;WindowManagerService wm = null;BluetoothService bluetooth = null;UsbService usb = null;NotificationManagerService notification = null;StatusBarManagerService statusBar = null;……power = new PowerManagerService();ServiceManager.addService(Context.POWER_SERVICE, power);……// ActivityManagerService作为ApplicationFramework最重要的服务ActivityManagerService.setSystemProcess();ActivityManagerService.installSystemProviders();ActivityManagerService.self().setWindowManager(wm);   // We now tell the activity manager it is okay to run third party
　　// code.  It will call back into us once it has gotten to the state
　　// where third party code can really run (but before it has actually
　　// started launching the initial applications), for us to complete our
　　// initialization.
　　//系统服务初始化准备就绪，通知各个模块ActivityManagerService.self().systemReady(new Runnable() {public void run() {startSystemUi(contextF);batteryF.systemReady();networkManagementF.systemReady();usbF.systemReady();……// It is now okay to let the various system services start their// third party code...appWidgetF.systemReady(safeMode);wallpaperF.systemReady();}});////BOOTPROFaddBootEvent(new String("Android:SysServerInit_END"));Looper.loop();
}

 public void systemReady(final Runnable goingCallback) {……
　　　　//ready callbackif (goingCallback != null)goingCallback.run();synchronized (this) {// Start up initial activity.// ActivityStack mMainStack;mMainStack.resumeTopActivityLocked(null);}
……}final boolean resumeTopActivityLocked(ActivityRecord prev) {// Find the first activity that is not finishing.ActivityRecord next = topRunningActivityLocked(null);if (next == null) {
　　　　// There are no more activities!  Let's just start up the// Launcher...if (mMainStack) {//ActivityManagerService mService;return mService.startHomeActivityLocked();}}……
}