消息注册机制更加丰富了MessageHandle的流程，它把过程严格阶段化了，分成消息注册和通知消息处理两个部分，让人一目了然。
消息注册机制的总体思想是：一个对象中开辟一个空间用于存放Message，当调用regist方法时将Message存放进去，当其调用notify方法时将所有Message取出并发送到MessageQueue中等待处理。
下面是模拟程序，提供Registrant，RegistrantList，AsyncResult，MiddleUser类
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package com.zte.liu.registermessage;
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public class AsyncResult {
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MessageParmeters parmList;
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Object result;
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Throwable exception;
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public Throwable getException() {
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return exception;
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}
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public void setException(Throwable exception) {
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this.exception = exception;
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}
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AsyncResult(Object result, Throwable exception){
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parmList = new MessageParmeters();
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this.result = result;
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this.exception = exception;
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}
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public MessageParmeters getMessageParms(){
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return parmList;
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}
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public Object getResult(){
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return result;
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}
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public void setResult(Object result){
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this.result = result;
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}
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public AsyncResult refresh(Object parm){
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parmList.refresh(parm);
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return this;
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}
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}
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package com.zte.liu.registermessage;
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import com.zte.liu.messagehandler.Handler;
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public class MiddleUser {
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RegistrantList registrantList = new RegistrantList();
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public void registForReason(Handler handler, int what, Object firstParms){
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registrantList.add(handler, what, firstParms);
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}
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public void notifyRegistrant(Object secondParms, Throwable exception){
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registrantList.notifyRegistrantList(secondParms, exception);
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}
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public void unRegistForReason(int what){
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registrantList.remove(what);
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}
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}
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package com.zte.liu.registermessage;
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import com.zte.liu.messagehandler.Handler;
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import com.zte.liu.messagehandler.Message;
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public class Registrant {
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private Message msg = null;
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Registrant(Handler handler, int what, Object firstParms){
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msg = new Message(what, handler, new AsyncResult(null,null).refresh(firstParms));
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}
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public void notifyRegistrant(Object secondParms, Throwable exception){
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if(msg == null){
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return;
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}
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AsyncResult asyncResult = (AsyncResult)msg.getObj();
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asyncResult.refresh(secondParms).setException(exception);
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msg.sendToTarget();
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}
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public Message getMessage(){
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return msg;
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}
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}
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package com.zte.liu.registermessage;
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import java.util.ArrayList;
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import com.zte.liu.messagehandler.Handler;
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public class RegistrantList {
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private ArrayList<Registrant> registrantList = new ArrayList<Registrant>();
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public synchronized void add(Handler handler, int what, Object firstParms){
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Registrant registrant = new Registrant(handler, what, firstParms);
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registrantList.add(registrant);
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}
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public synchronized void remove(int what){
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for(int i=0; i<registrantList.size(); i++){
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if(((Registrant)registrantList.get(i)).getMessage().getId() == what){
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registrantList.remove(i);
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}
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}
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}
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public synchronized void notifyRegistrantList(Object secondParms, Throwable exception){
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for(int i=0; i<registrantList.size(); i++){
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Registrant registrant = (Registrant)registrantList.get(i);
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registrant.notifyRegistrant(secondParms, exception);
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}
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}
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}
