Java异步编程第2篇
作者:互联网
假如如今有一个Buttonbutton,Buttonbutton上有click和doubleclick事件。
两个不同的事件须要进行不同的处理。这时候就须要为对应的事件注冊Listener了。改动后的文件夹组织结构例如以下:
1、事件基本类的编写例如以下:
package com.event.test02;
public class Event {
public String action; // 事件名称
public String message; // 附加说明
/**
* @param action
* @param message
*/
public Event(String action, String message) {
this.action = action;
this.message = message;
}
}
package com.event.test02;
public class EventNames {
/**
* 单击事件
*/
public static final String Click = "Click";
/**
* 双击事件
*/
public static final String DoubleClick = "DoubleClick";
}
package com.event.test02;
import com.event.test02.exception.EventAlreadyRegisteredException;
import com.event.test02.handler.ClickHandler;
import com.event.test02.handler.DoubleClickHandler;
public class EventBinder {
public static void bindEvents(){
try {
EventDispatcher eventDispatcher = EventDispatcher.getInstance();
eventDispatcher.addEventListener(EventNames.Click, new ClickHandler());
eventDispatcher.addEventListener(EventNames.DoubleClick, new DoubleClickHandler());
} catch (EventAlreadyRegisteredException e) {
e.printStackTrace();
}
}
}
package com.event.test02;
import java.util.HashMap;
import com.event.test02.exception.EventAlreadyRegisteredException;
import com.event.test02.exception.UnknowEventException;
import com.event.test02.handler.EventListener;
public class EventDispatcher {
private static EventDispatcher eventDispatcher;
private EventDispatcher(){}
/**
* 获取实例
* @return EventDispatcher
*/
public static EventDispatcher getInstance(){
if(eventDispatcher == null){
eventDispatcher = new EventDispatcher();
}
return eventDispatcher;
}
HashMap<String, EventListener> map = new HashMap<String, EventListener>();
/**
* 加入监听器
* @param event
* @param listener
* @throws EventAlreadyRegisteredException
*/
public void addEventListener(String event, EventListener listener)
throws EventAlreadyRegisteredException {
if(map.get(event) != null){
throw new EventAlreadyRegisteredException();
}
map.put(event, listener);
}
/**
* 移除某一个监听器
* @param event
*/
public void removeEventListener(String event) {
map.remove(event);
}
/**
* @param e
* @throws UnknowEventException
*/
public void dispatchEvent(Event e) throws UnknowEventException {
EventListener listener = map.get(e.action);
if(listener == null){
throw new UnknowEventException();
}else{
listener.handleEvent(e);
}
}
/**
* 移除全部监听器
*/
public void removeAllListeners() {
map.clear();
}
}
package com.event.test02.handler;
import com.event.test02.Event;
public interface EventListener {
public void handleEvent(Event e);
}
package com.event.test02.handler;
import com.event.test02.Event;
public class DoubleClickHandler implements EventListener{
public void handleEvent(Event e) {
System.out.println("hand doubleclick event ....");
}
}
package com.event.test02.handler;
import com.event.test02.Event;
public class ClickHandler implements EventListener{
public void handleEvent(Event e) {
System.out.println("hand click event ....");
}
}
3、自己定义异常处理类
package com.event.test02.exception;
public class EventAlreadyRegisteredException extends Exception {
private static final long serialVersionUID = 741821449383395827L;
}
package com.event.test02.exception;
public class UnknowEventException extends Exception {
private static final long serialVersionUID = 4829929946904208467L;
}
最后执行的结果例如以下:hand click event ....
hand doubleclick event ....
如上的程序灵活了不少,其组织也很清晰。
在使用的时候不要拘泥于某一种形式。
在实际项目开发的过程中,能够将很多大的操作封装为一个专门的任务Task,也能够启动若干个承担不同任务的线程。仅仅要给这些任务定义一个事件名称,当须要执行某个任务时,利用事件触发就可以。
有兴趣的读者能够去看一个框架disruptor,推荐的地址例如以下:
标签:异步,Java,编程,public,test02,import,com,event,Event 来源: https://www.cnblogs.com/ldxsuanfa/p/10801644.html