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webSocket 简单实例

2015-11-18 11:50 399 查看
什么是webSocket？webSocket 是解决服务器端和客户端通信实时的技术。ajax也可以通信，但是他做不到实时。在webSocket之前我们想要实时效果，都是要通过轮询的方式，显然这样很浪费资源。webSocket 的强大在于，比起ajax 需要从客户端发起请求，webSocket的 服务端与客户端可以相互实时推送消息。如何使用webSocket？首先你得有一个支持它的浏览器。（IE 是不支持的）创建socket后 ，客户端可以通过 onopen,onmessage,onclose,onerror 这四个时间对socket进行响应。举个栗子：环境：tomcat7或以上。jdk7 或以上 1.webSocketTest.java package instance;import java.io.IOException;import javax.websocket.OnClose;import javax.websocket.OnMessage;import javax.websocket.OnOpen;import javax.websocket.Session;import javax.websocket.server.ServerEndpoint;<span style="color:#ff6666;">@ServerEndpoint("/websocket")</span>public class WebSocketTest {@OnMessagepublic void onMessage(String message, Session session)throws IOException, InterruptedException {// Print the client message for testing purposesSystem.out.println("Received: " + message);// Send the first message to the clientsession.getBasicRemote().sendText("This is the first server message");// Send 3 messages to the client every 5 secondsint sentMessages = 0;while(sentMessages < 3){Thread.sleep(5000);session.getBasicRemote().sendText("This is an intermediate server message. Count: "+ sentMessages);sentMessages++;}// Send a final message to the clientsession.getBasicRemote().sendText("This is the last server message");}@OnOpenpublic void onOpen() {System.out.println("Client connected");}@OnClosepublic void onClose() {System.out.println("Connection closed");}}2.page.html<!DOCTYPE html><html><head><title>Testing websockets</title></head><body><div><input type="submit" value="Start" onclick="start()" /></div><div id="messages"></div><script type="text/javascript">var webSocket =new WebSocket('ws://localhost:8080/webScoket/<span style="color:#ff6666;">websocket</span>');webSocket.onerror = function(event) {onError(event)};webSocket.onopen = function(event) {onOpen(event)};webSocket.onmessage = function(event) {onMessage(event)};function onMessage(event) {document.getElementById('messages').innerHTML+= '<br />' + event.data;}function onOpen(event) {document.getElementById('messages').innerHTML= 'Connection established';}function onError(event) {alert(event.data);}function start() {webSocket.send('hello');return false;}</script></body></html>这里要注意：var webSocket =new WebSocket('ws://localhost:8080/webScoket/websocket');
其中：一个是项目名称，一个是注解的服务器名称
到此你启动服务器，运行page.html 出现如图，就说明成功了
                                            

                                        

                        
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                                                java
                                                webSocket
                                                

                        

                    


                

            


            

                
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