Android的System Server

http://www.cnblogs.com/armlinux/archive/2012/01/12/2396769.html

System Server是Android系統的核心，他在Dalvik虛拟機啟動後立即開始初始化和運作。其它的系統服務在System Server程序的環境中運作。/base/services/java/com/android/server/SystemServer.java

Java代碼

native public static void init1(String[] args);
public static void main(String[] args) {
if (System.currentTimeMillis() < EARLIEST_SUPPORTED_TIME) {
// If a device's clock is before 1970 (before 0), a lot of
// APIs crash dealing with negative numbers, notably
// java.io.File#setLastModified, so instead we fake it and
// hope that time from cell towers or NTP fixes it
// shortly.
Slog.w(TAG, "System clock is before 1970; setting to 1970.");
SystemClock.setCurrentTimeMillis(EARLIEST_SUPPORTED_TIME);
}
if (SamplingProfilerIntegration.isEnabled()) {
SamplingProfilerIntegration.start();
timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
SamplingProfilerIntegration.writeSnapshot("system_server");
}
}, SNAPSHOT_INTERVAL, SNAPSHOT_INTERVAL);
}
// The system server has to run all of the time, so it needs to be
// as efficient as possible with its memory usage.
VMRuntime.getRuntime().setTargetHeapUtilization(0.8f);
System.loadLibrary("android_servers");
init1(args);
}
public static final void init2() {
Slog.i(TAG, "Entered the Android system server!");
Thread thr = new ServerThread();
thr.setName("android.server.ServerThread");
thr.start();
}

在main函數中，首先檢查系統時間設定和SamplingProfiler。然後加載一個叫android_servers的本地庫，他提供本地方法的接口（源程式在framework/base/services/jni/目錄中）。然後調用本地方法設定服務。具體執行設定的代碼在frameworks/base/cmds/system_server/library/system_init.cpp中。

C代碼

Android的System Server

extern "C" status_t system_init()
{
LOGI("Entered system_init()");
sp<ProcessState> proc(ProcessState::self());
sp<IServiceManager> sm = defaultServiceManager();
LOGI("ServiceManager: %p\n", sm.get());
sp<GrimReaper> grim = new GrimReaper();
sm->asBinder()->linkToDeath(grim, grim.get(), 0);
char propBuf[PROPERTY_VALUE_MAX];
property_get("system_init.startsurfaceflinger", propBuf, "1");
if (strcmp(propBuf, "1") == 0) {
// Start the SurfaceFlinger
SurfaceFlinger::instantiate();
}
// Start the sensor service
SensorService::instantiate();
// On the simulator, audioflinger et al don't get started the
// same way as on the device, and we need to start them here
if (!proc->supportsProcesses()) {
// Start the AudioFlinger
AudioFlinger::instantiate();
// Start the media playback service
MediaPlayerService::instantiate();
// Start the camera service
CameraService::instantiate();
// Start the audio policy service
AudioPolicyService::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.
LOGI("System server: starting Android runtime.\n");
AndroidRuntime* runtime = AndroidRuntime::getRuntime();
LOGI("System server: starting Android services.\n");
runtime->callStatic("com/android/server/SystemServer", "init2");
// If running in our own process, just go into the thread
// pool. Otherwise, call the initialization finished
// func to let this process continue its initilization.
if (proc->supportsProcesses()) {
LOGI("System server: entering thread pool.\n");
ProcessState::self()->startThreadPool();
IPCThreadState::self()->joinThreadPool();
LOGI("System server: exiting thread pool.\n");
}
return NO_ERROR;
}

等初始化傳感器，視訊，音頻等服務後，調用一個回調方法init2 (在SystemServer.java中)。在上面的代碼可以看到，這個方法開啟了ServerThread來初始化其它的服務。

Java代碼

Android的System Server

public void run() {
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_SYSTEM_RUN,
SystemClock.uptimeMillis());
Looper.prepare();
android.os.Process.setThreadPriority(
android.os.Process.THREAD_PRIORITY_FOREGROUND);
BinderInternal.disableBackgroundScheduling(true);
android.os.Process.setCanSelfBackground(false);
// Check whether we failed to shut down last time we tried.
{
final String shutdownAction = SystemProperties.get(
ShutdownThread.SHUTDOWN_ACTION_PROPERTY, "");
if (shutdownAction != null && shutdownAction.length() > 0) {
boolean reboot = (shutdownAction.charAt(0) == '1');
final String reason;
if (shutdownAction.length() > 1) {
reason = shutdownAction.substring(1, shutdownAction.length());
} else {
reason = null;
}
ShutdownThread.rebootOrShutdown(reboot, reason);
}
}
String factoryTestStr = SystemProperties.get("ro.factorytest");
int factoryTest = "".equals(factoryTestStr) ? SystemServer.FACTORY_TEST_OFF
: Integer.parseInt(factoryTestStr);
LightsService lights = null;
PowerManagerService power = null;
BatteryService battery = null;
ConnectivityService connectivity = null;
IPackageManager pm = null;
Context context = null;
WindowManagerService wm = null;
BluetoothService bluetooth = null;
BluetoothA2dpService bluetoothA2dp = null;
HeadsetObserver headset = null;
DockObserver dock = null;
UsbService usb = null;
UiModeManagerService uiMode = null;
RecognitionManagerService recognition = null;
ThrottleService throttle = null;
// Critical services...
try {
Slog.i(TAG, "Entropy Service");
ServiceManager.addService("entropy", new EntropyService());
Slog.i(TAG, "Power Manager");
power = new PowerManagerService();
ServiceManager.addService(Context.POWER_SERVICE, power);
Slog.i(TAG, "Activity Manager");
context = ActivityManagerService.main(factoryTest);
Slog.i(TAG, "Telephony Registry");
ServiceManager.addService("telephony.registry", new TelephonyRegistry(context));
AttributeCache.init(context);
Slog.i(TAG, "Package Manager");
pm = PackageManagerService.main(context,
factoryTest != SystemServer.FACTORY_TEST_OFF);
ActivityManagerService.setSystemProcess();
mContentResolver = context.getContentResolver();
// The AccountManager must come before the ContentService
try {
Slog.i(TAG, "Account Manager");
ServiceManager.addService(Context.ACCOUNT_SERVICE,
new AccountManagerService(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Account Manager", e);
}
Slog.i(TAG, "Content Manager");
ContentService.main(context,
factoryTest == SystemServer.FACTORY_TEST_LOW_LEVEL);
Slog.i(TAG, "System Content Providers");
ActivityManagerService.installSystemProviders();
Slog.i(TAG, "Battery Service");
battery = new BatteryService(context);
ServiceManager.addService("battery", battery);
Slog.i(TAG, "Lights Service");
lights = new LightsService(context);
Slog.i(TAG, "Vibrator Service");
ServiceManager.addService("vibrator", new VibratorService(context));
// only initialize the power service after we have started the
// lights service, content providers and the battery service.
power.init(context, lights, ActivityManagerService.getDefault(), battery);
Slog.i(TAG, "Alarm Manager");
AlarmManagerService alarm = new AlarmManagerService(context);
ServiceManager.addService(Context.ALARM_SERVICE, alarm);
Slog.i(TAG, "Init Watchdog");
Watchdog.getInstance().init(context, battery, power, alarm,
ActivityManagerService.self());
Slog.i(TAG, "Window Manager");
wm = WindowManagerService.main(context, power,
factoryTest != SystemServer.FACTORY_TEST_LOW_LEVEL);
ServiceManager.addService(Context.WINDOW_SERVICE, wm);
((ActivityManagerService)ServiceManager.getService("activity"))
.setWindowManager(wm);
// Skip Bluetooth if we have an emulator kernel
// TODO: Use a more reliable check to see if this product should
// support Bluetooth - see bug 988521
if (SystemProperties.get("ro.kernel.qemu").equals("1")) {
Slog.i(TAG, "Registering null Bluetooth Service (emulator)");
ServiceManager.addService(BluetoothAdapter.BLUETOOTH_SERVICE, null);
} else if (factoryTest == SystemServer.FACTORY_TEST_LOW_LEVEL) {
Slog.i(TAG, "Registering null Bluetooth Service (factory test)");
ServiceManager.addService(BluetoothAdapter.BLUETOOTH_SERVICE, null);
} else {
Slog.i(TAG, "Bluetooth Service");
bluetooth = new BluetoothService(context);
ServiceManager.addService(BluetoothAdapter.BLUETOOTH_SERVICE, bluetooth);
bluetooth.initAfterRegistration();
bluetoothA2dp = new BluetoothA2dpService(context, bluetooth);
ServiceManager.addService(BluetoothA2dpService.BLUETOOTH_A2DP_SERVICE,
bluetoothA2dp);
int bluetoothOn = Settings.Secure.getInt(mContentResolver,
Settings.Secure.BLUETOOTH_ON, 0);
if (bluetoothOn > 0) {
bluetooth.enable();
}
}
} catch (RuntimeException e) {
Slog.e("System", "Failure starting core service", e);
}
DevicePolicyManagerService devicePolicy = null;
StatusBarManagerService statusBar = null;
InputMethodManagerService imm = null;
AppWidgetService appWidget = null;
NotificationManagerService notification = null;
WallpaperManagerService wallpaper = null;
LocationManagerService location = null;
if (factoryTest != SystemServer.FACTORY_TEST_LOW_LEVEL) {
try {
Slog.i(TAG, "Device Policy");
devicePolicy = new DevicePolicyManagerService(context);
ServiceManager.addService(Context.DEVICE_POLICY_SERVICE, devicePolicy);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting DevicePolicyService", e);
}
try {
Slog.i(TAG, "Status Bar");
statusBar = new StatusBarManagerService(context);
ServiceManager.addService(Context.STATUS_BAR_SERVICE, statusBar);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting StatusBarManagerService", e);
}
try {
Slog.i(TAG, "Clipboard Service");
ServiceManager.addService(Context.CLIPBOARD_SERVICE,
new ClipboardService(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Clipboard Service", e);
}
try {
Slog.i(TAG, "Input Method Service");
imm = new InputMethodManagerService(context, statusBar);
ServiceManager.addService(Context.INPUT_METHOD_SERVICE, imm);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Input Manager Service", e);
}
try {
Slog.i(TAG, "NetStat Service");
ServiceManager.addService("netstat", new NetStatService(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting NetStat Service", e);
}
try {
Slog.i(TAG, "NetworkManagement Service");
ServiceManager.addService(
Context.NETWORKMANAGEMENT_SERVICE,
NetworkManagementService.create(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting NetworkManagement Service", e);
}
try {
Slog.i(TAG, "Connectivity Service");
connectivity = ConnectivityService.getInstance(context);
ServiceManager.addService(Context.CONNECTIVITY_SERVICE, connectivity);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Connectivity Service", e);
}
try {
Slog.i(TAG, "Throttle Service");
throttle = new ThrottleService(context);
ServiceManager.addService(
Context.THROTTLE_SERVICE, throttle);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting ThrottleService", e);
}
try {
Slog.i(TAG, "Accessibility Manager");
ServiceManager.addService(Context.ACCESSIBILITY_SERVICE,
new AccessibilityManagerService(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Accessibility Manager", e);
}
try {
Slog.i(TAG, "Mount Service");
ServiceManager.addService("mount", new MountService(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Mount Service", e);
}
try {
Slog.i(TAG, "Notification Manager");
notification = new NotificationManagerService(context, statusBar, lights);
ServiceManager.addService(Context.NOTIFICATION_SERVICE, notification);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Notification Manager", e);
}
try {
Slog.i(TAG, "Device Storage Monitor");
ServiceManager.addService(DeviceStorageMonitorService.SERVICE,
new DeviceStorageMonitorService(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting DeviceStorageMonitor service", e);
}
try {
Slog.i(TAG, "Location Manager");
location = new LocationManagerService(context);
ServiceManager.addService(Context.LOCATION_SERVICE, location);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Location Manager", e);
}
try {
Slog.i(TAG, "Search Service");
ServiceManager.addService(Context.SEARCH_SERVICE,
new SearchManagerService(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Search Service", e);
}
if (INCLUDE_DEMO) {
Slog.i(TAG, "Installing demo data...");
(new DemoThread(context)).start();
}
try {
Slog.i(TAG, "DropBox Service");
ServiceManager.addService(Context.DROPBOX_SERVICE,
new DropBoxManagerService(context, new File("/data/system/dropbox")));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting DropBoxManagerService", e);
}
try {
Slog.i(TAG, "Wallpaper Service");
wallpaper = new WallpaperManagerService(context);
ServiceManager.addService(Context.WALLPAPER_SERVICE, wallpaper);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Wallpaper Service", e);
}
try {
Slog.i(TAG, "Audio Service");
ServiceManager.addService(Context.AUDIO_SERVICE, new AudioService(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Audio Service", e);
}
try {
Slog.i(TAG, "Headset Observer");
// Listen for wired headset changes
headset = new HeadsetObserver(context);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting HeadsetObserver", e);
}
try {
Slog.i(TAG, "Dock Observer");
// Listen for dock station changes
dock = new DockObserver(context, power);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting DockObserver", e);
}
try {
Slog.i(TAG, "USB Service");
// Listen for USB changes
usb = new UsbService(context);
ServiceManager.addService(Context.USB_SERVICE, usb);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting UsbService", e);
}
try {
Slog.i(TAG, "UI Mode Manager Service");
// Listen for UI mode changes
uiMode = new UiModeManagerService(context);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting UiModeManagerService", e);
}
try {
Slog.i(TAG, "Backup Service");
ServiceManager.addService(Context.BACKUP_SERVICE,
new BackupManagerService(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Backup Service", e);
}
try {
Slog.i(TAG, "AppWidget Service");
appWidget = new AppWidgetService(context);
ServiceManager.addService(Context.APPWIDGET_SERVICE, appWidget);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting AppWidget Service", e);
}
try {
Slog.i(TAG, "Recognition Service");
recognition = new RecognitionManagerService(context);
} catch (Throwable e) {
Slog.e(TAG, "Failure starting Recognition Service", e);
}
try {
Slog.i(TAG, "DiskStats Service");
ServiceManager.addService("diskstats", new DiskStatsService(context));
} catch (Throwable e) {
Slog.e(TAG, "Failure starting DiskStats Service", e);
}
}
// make sure the ADB_ENABLED setting value matches the secure property value
Settings.Secure.putInt(mContentResolver, Settings.Secure.ADB_ENABLED,
"1".equals(SystemProperties.get("persist.service.adb.enable")) ? 1 : 0);
// register observer to listen for settings changes
mContentResolver.registerContentObserver(Settings.Secure.getUriFor(Settings.Secure.ADB_ENABLED),
false, new AdbSettingsObserver());
// Before things start rolling, be sure we have decided whether
// we are in safe mode.
final boolean safeMode = wm.detectSafeMode();
if (safeMode) {
try {
ActivityManagerNative.getDefault().enterSafeMode();
// Post the safe mode state in the Zygote class
Zygote.systemInSafeMode = true;
// Disable the JIT for the system_server process
VMRuntime.getRuntime().disableJitCompilation();
} catch (RemoteException e) {
}
} else {
// Enable the JIT for the system_server process
VMRuntime.getRuntime().startJitCompilation();
}
// It is now time to start up the app processes...
if (devicePolicy != null) {
devicePolicy.systemReady();
}
if (notification != null) {
notification.systemReady();
}
if (statusBar != null) {
statusBar.systemReady();
}
wm.systemReady();
power.systemReady();
try {
pm.systemReady();
} catch (RemoteException e) {
}
// These are needed to propagate to the runnable below.
final StatusBarManagerService statusBarF = statusBar;
final BatteryService batteryF = battery;
final ConnectivityService connectivityF = connectivity;
final DockObserver dockF = dock;
final UsbService usbF = usb;
final ThrottleService throttleF = throttle;
final UiModeManagerService uiModeF = uiMode;
final AppWidgetService appWidgetF = appWidget;
final WallpaperManagerService wallpaperF = wallpaper;
final InputMethodManagerService immF = imm;
final RecognitionManagerService recognitionF = recognition;
final LocationManagerService locationF = location;
// 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.
((ActivityManagerService)ActivityManagerNative.getDefault())
.systemReady(new Runnable() {
public void run() {
Slog.i(TAG, "Making services ready");
if (statusBarF != null) statusBarF.systemReady2();
if (batteryF != null) batteryF.systemReady();
if (connectivityF != null) connectivityF.systemReady();
if (dockF != null) dockF.systemReady();
if (usbF != null) usbF.systemReady();
if (uiModeF != null) uiModeF.systemReady();
if (recognitionF != null) recognitionF.systemReady();
Watchdog.getInstance().start();
// It is now okay to let the various system services start their
// third party code...
if (appWidgetF != null) appWidgetF.systemReady(safeMode);
if (wallpaperF != null) wallpaperF.systemReady();
if (immF != null) immF.systemReady();
if (locationF != null) locationF.systemReady();
if (throttleF != null) throttleF.systemReady();
}
});
// For debug builds, log event loop stalls to dropbox for analysis.
if (StrictMode.conditionallyEnableDebugLogging()) {
Slog.i(TAG, "Enabled StrictMode for system server main thread.");
}
Looper.loop();
Slog.d(TAG, "System ServerThread is exiting!");
}

這裡啟動的沒一個程序都作為一個Dalvik線程而存在于SystemServer程序裡面。

Android的System Server

Android的System Server

繼續閱讀

專訪鄧凡平：深入了解Android

與專家面對面：Android開發入門問與答

Android MVP架構MVCMVP

mvp初探

Android常用工具類簡介目錄

android常用工具類轉載自：http://www.trinea.cn/android/android-common-utils/Android常用工具類

Android常用工具類ToastUtilsSizeUtilsLogUtilsRetrofitManagerAnimUtil

Android Studio 0.8.0解決 Failure [INSTALL_FAILED_OLDER_SDK] 問題

Android – ListView 中添加按鈕，動态删除添加ItemView的操作

Kotlin的ListView與RecyclerView的簡單應用

關于公司的那些坑：Android Studio篇

android SQLite事務和kotlin協程

無法正常編譯錯誤Compilation failed to complete

關于Gradle配置的小結

AOP程式設計_Android優雅權限架構(1)概念基礎，2021金三銀四前言正文大綱正文

Android APK檔案反編譯Android APK檔案反編譯