mysql数据变化通通知机制_深入理解Notification机制

先贴上这些源码里面相关的文件：

framework/base/core/java/android/app/NotificationManager.java

framework/base/services/java/com/android/server/NotificationManagerService.java{@hide} extends INotificationManager.Stub

framework/base/services/java/com/android/server/StatusBarManagerService.java extends IStatusBarService.Stub

framework/base/core/java/com/android/internal/statusbar/StatusBarNotification implements Parcelable

framework/base/core/java/com/android/internal/statusbar/IStatusBar.aidl

framework/base/core/java/com/android/internal/statusbar/IStatusBarService.aidl

framework/base/core/java/com/android/internal/statusbar/StatusBarNotification.aidl

framework/base/packages/SystemUI/src/com/android/systemui/statusbar/StatusBarService.java extends Service implements CommandQueue.Callbacks

framework/base/packages/SystemUI/src/com/android/systemui/statusbar/CommandQueue.java extends IStatusBar.Stub

1>.系统启动的时候：framework/base/services/java/com/android/server/SystemServer.java中：

try{

Slog.i(TAG,"Status Bar");

statusBar= newStatusBarManagerService(context);

ServiceManager.addService(Context.STATUS_BAR_SERVICE, statusBar);

}catch(Throwable e) {

Slog.e(TAG,"Failure starting StatusBarManagerService", e);

}try{

Slog.i(TAG,"Notification Manager");

notification= newNotificationManagerService(context, statusBar, lights);

ServiceManager.addService(Context.NOTIFICATION_SERVICE, notification);

}catch(Throwable e) {

Slog.e(TAG,"Failure starting Notification Manager", e);

}

这段代码是注册状态栏管理和通知管理这两个服务。

2>.在StatusBarManagerService.java中，有addNotification，removeNotification,updateNotification等方法用于管理传递给他的通知对象。这个类是一些管理方法，实际执行相关动作的是在IStatusBar.java里面，这个是framework/base/core/java/com/android/internal/statusbar/IStatusBar.aidl自动生成的用于IPC的类。

拿addNotification方法示范：

publicIBinder addNotification(StatusBarNotification notification) {synchronized(mNotifications) {

IBinder key= newBinder();

mNotifications.put(key, notification);if (mBar != null) {try{

mBar.addNotification(key, notification);

}catch(RemoteException ex) {

}

}returnkey;

}

这里的mBar其实就是IStatusBar的实例

volatile IStatusBar mBar;

为了防止NPE，每次使用mBar都先判断是否为null，mBar是在方法registerStatusBar中传递进来的。

public voidregisterStatusBar(IStatusBar bar, StatusBarIconList iconList,

List notificationKeys, Listnotifications) {

enforceStatusBarService();

Slog.i(TAG,"registerStatusBar bar=" +bar);

mBar=bar;synchronized(mIcons) {

iconList.copyFrom(mIcons);

}synchronized(mNotifications) {for (Map.Entrye: mNotifications.entrySet()) {

notificationKeys.add(e.getKey());

notifications.add(e.getValue());

}

framework/base/packages/SystemUI/src/com/android/systemui/statusbar/CommandQueue.java实现IStatusBar.java接口，

framework/base/packages/SystemUI/src/com/android/systemui/statusbar/StatusBarService.java提供IStatusBar相关服务。

CommandQueue.java中，IStatusBar.java里面对应的方法是用callback的形式调用的，callback的实现当然就在对应的服务提供类也就是StatusBarService.java中提供的啦。

CommandQueue.java中：

public voidaddNotification(IBinder key, StatusBarNotification notification) {synchronized(mList) {

NotificationQueueEntry ne= newNotificationQueueEntry();

ne.key=key;

ne.notification=notification;

mHandler.obtainMessage(MSG_ADD_NOTIFICATION,0, 0, ne).sendToTarget();//这句话对应的mHandler执行语句是：//final NotificationQueueEntry ne = (NotificationQueueEntry)msg.obj;//mCallbacks.addNotification(ne.key, ne.notification);//也就是调用回调函数里面的addNotification。

}

在StatusBarService.java中：

mCommandQueue = new CommandQueue(this, iconList);//StatusBarService实现了CommandQueue中的CommandQueue.Callbacks接口

mBarService =IStatusBarService.Stub.asInterface(

ServiceManager.getService(Context.STATUS_BAR_SERVICE));try{//将IStatusBar实现类的对象传递到StatusBarManagerService.java中，这里的mCommandQueue就是上面对应的mBar啦。

mBarService.registerStatusBar(mCommandQueue, iconList, notificationKeys, notifications);

}catch(RemoteException ex) {//If the system process isn't there we're doomed anyway.

}

最终执行状态栏更新通知等事件都是在实现的CommandQueue.Callbacks里面执行。还是以addNotification为例：

public voidaddNotification(IBinder key, StatusBarNotification notification) {boolean shouldTick = true;if (notification.notification.fullScreenIntent != null) {

shouldTick= false;

Slog.d(TAG,"Notification has fullScreenIntent; sending fullScreenIntent");try{

notification.notification.fullScreenIntent.send();

}catch(PendingIntent.CanceledException e) {

}

StatusBarIconView iconView=addNotificationViews(key, notification);if (iconView == null) return;//。。。以下省略N字。

大致流程就是:调用StatusBarManagerService.java中的addNotification方法->(mBar不为空的话)执行mBar.addNotification(key, notification);->对应的是CommandQueue中的addNotification(IBinder key, StatusBarNotification notification)->CommandQueue中的mCallbacks.addNotification(ne.key, ne.notification);->StatusBarService中的addNotification。

3>.上面是提供相关功能的一些类，具体的notification的管理类是framework/base/services/java/com/android/server/NotificationManagerService.java，从该类的定义public class NotificationManagerService extends INotificationManager.Stub可以知道

他是用来实现接口中INotificationManager中定义的相关方法并向外部提供服务的类。主要向外提供public void enqueueNotificationWithTag(String pkg, String tag, int id, Notification notification,int[] idOut)方法。该方法实际上是调用public void enqueueNotificationInternal(String pkg, int callingUid, int callingPid,String tag, int id, Notification notification, int[] idOut)，他里面提供了notification的具体处理方法。

摘取部分代码片段看看：

if (notification.icon != 0) {

StatusBarNotification n= newStatusBarNotification(pkg, id, tag,

r.uid, r.initialPid, notification);if (old != null && old.statusBarKey != null) {

r.statusBarKey=old.statusBarKey;long identity =Binder.clearCallingIdentity();try{

mStatusBar.updateNotification(r.statusBarKey, n);

}finally{

Binder.restoreCallingIdentity(identity);

}

}else{//省略。。。

当判断好需要更新通知的时候调用mStatusBar.updateNotification(r.statusBarKey, n);方法，这个就是StatusBarManagerService.java中的addNotification方法，这样就进入上面所说的处理流程了。

4>. 在3中的NotificationManagerService.java是管理notification的服务，服务嘛就是用来调用的，调用他的就是大家熟悉的NotificationManager了。