Java 的Event機制淺析

通常java添加監聽類似C裡面的回調，通常在使用時比較簡單，自己定義的事件類（繼承EventObject)，定義監聽器接口(繼承EventListener)，定義一個者向量來保存添加的這些監聽器，通過addListenerremoveListener來操作。

但是監聽器如何被觸發的，從底層消息到啟動監聽器的流程是什麼樣子的？

將分篇來說明,下面以一個BossXi ,BossLi類來說明：

添加EmployeeEvent事件類：

package Company;

import java.util.EventObject;

public class EmployeeEvent extends EventObject{
private int m_nReason;

private int m_nType;

private Object m_sSource;

public EmployeeEvent(Object arg0,int reason , int type) {
super(arg0);
// TODO Auto-generated constructor stub
this.setType(type);
this.m_nReason = reason;
this.m_sSource = arg0;
}

/**
*
*/
private static final long serialVersionUID = 1L;

public static final int EVENT_WORK_ON = 0;

public static final int EVENT_WORK_OFF = 1;

public int getReason(){
return m_nReason;
}

public int getType(){
return m_nType;
}

public int setType(int nType){
return this.m_nType = nType;
}

public Object getSource(){
return (java.lang.Object)m_sSource;
}
}

添加EmployeeListener監聽接口：

package Company;

// 實現 EventListener接口
public interface EmployeeListener extends java.util.EventListener{

// 使用監聽器的時候，實現並添加到
public void onEmPloyeeEvent(EmployeeEvent empEvent);

}

添加分發消息接口MessageHandler：

package Company;

public interface MessageHandler {

public void processMessage(Message message);

}

添加消息Message類：

package Company;

public class Message {
public final static int TerminateType = -1;
public int type;
public Object data;
MessageHandler handler;

public Message(MessageHandler p, int t, Object d)
{
handler = p;
type = t;
data = d;
}

public boolean equals(Object o)
{
Message e = (Message) o;
return ((handler == e.handler) && (type == e.type) &&
data.equals(e.data));
}
}

更多詳情見請繼續閱讀下一頁的精彩內容： http://www.linuxidc.com/Linux/2014-05/101046p2.htm