/**

* 负责发送和处理消息

*/

public class Handler {

// 消息队列

private MessageQueue messageQueue;

// 消息泵

Looper looper;

public Handler() {

looper = Looper.getLocalLooper();

if (looper == null) {

throw new RuntimeException("Can't create handler inside thread that has not called Looper.prepare()");

}

messageQueue = looper.messageQueue;

}

public final void sendMessage(Message msg) {

MessageQueue queue = messageQueue;

if (queue != null) {

msg.handler = this;

queue.enqueueMessage(msg);

} else {

throw new RuntimeException(this + " sendMessage() called with no mQueue");

}

}

/**

* 子类必须实现此方法接收处理消息

* Subclasses must implement this to receive messages.

*/

public void handleMessage(Message msg) {

}

/**

* 在此处理系统消息

* Handle system messages here.

*/

public void dispatchMessage(Message msg) {

handleMessage(msg);

}

}