java spring websocket

1.简介：WebSocket协议是基于TCP的一种新的网络协议。它实现了浏览器与服务器实现持久连接的全双工双向通信，客户端可以主动的向服务器发起请求以获取数据，服务器也可以主动向客户端返回响应以传输数据。
在JS中创建WebSocket后，会有一个HTTP请求发向浏览器以发起请求。在取得服务器响应后，建立的连接会使用HTTP升级将HTTP协议转换为WebSocket协议。
也就是说，使用标准的HTTP协议无法实现WebSocket，只有支持那些协议的专门浏览器才能正常工作。
WebSocket是应用层协议，是TCP/IP协议的子集，通过HTTP/1.1协议的101状态码进行握手。也就是说，WebSocket协议的建立需要先借助HTTP协议，在服务器返回101状态码之后，就可以进行websocket全双工双向通信了，就没有HTTP协议什么事情了。
WebScoket使用了自定义协议，所以URL与HTTP协议略有不同。未加密的连接为ws://，而不是http://。加密的连接为wss://，而不是https://。
2.推送：
1.传统推送采用ajax轮询，是客户端向服务器发起HTTP请求，无论数据是否更新，服务器都会传输数据，一个request对应一个response。
2.dwr推送，一个类似于ajax的框架，可以将后台代码转换成js，前端页面js调用后台，也可以后台推送前端。

3.websocket推送，客户端与服务器建立http连接，服务端可以随时向客户端进行推送。

3.用法：

一、java websocket

1.下载java websocket包，maven下载

<!-- java-websocket -->
<dependency><groupId>javax.websocket</groupId><artifactId>javax.websocket-api</artifactId><version>1.1</version><scope>provided</scope>
</dependency>

2.java websocket类

package com.ss.websocket;import org.springframework.beans.factory.annotation.Autowired;
import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArraySet;
//要求：Tomcat从7.0.27开始支持WebSocket，从7.0.47开始支持JSR-356，下面的Demo代码也是需要部署在Tomcat7.0.47上才能运行。
//该注解用来指定一个URI，客户端可以通过这个URI来连接到WebSocket。类似Servlet的注解mapping。无需在web.xml中配置。
@ServerEndpoint("/javaWebsocket")
public class JavaWebsocket {//静态变量，用来记录当前在线连接数。应该把它设计成线程安全的。private static int onlineCount = 0;//concurrent包的线程安全Set，用来存放每个客户端对应的MyWebSocket对象。若要实现服务端与单一客户端通信的话，可以使用Map来存放，其中Key可以为用户标识private static CopyOnWriteArraySet<JavaWebsocket> webSocketSet = new CopyOnWriteArraySet<JavaWebsocket>();private static Map<Session,JavaWebsocket> websocketMap = new HashMap();//与某个客户端的连接会话，需要通过它来给客户端发送数据private Session session;/*** 连接建立成功调用的方法* @param session  可选的参数。session为与某个客户端的连接会话，需要通过它来给客户端发送数据*/@OnOpenpublic void onOpen(Session session){this.session = session;webSocketSet.add(this);     //加入set中websocketMap.put(session,this);System.out.println("有新连接加入！当前在线人数为" +websocketMap.size());}/*** 连接关闭调用的方法*/@OnClosepublic void onClose(){webSocketSet.remove(this);  //从set中删除websocketMap.remove(this);System.out.println("有一连接关闭！当前在线人数为" +websocketMap.size());}/*** 收到客户端消息后调用的方法* @param message 客户端发送过来的消息* @param session 可选的参数*/@OnMessagepublic void onMessage(String message, Session session) {System.out.println(session.getId()+"来自客户端的消息:" + message);//群发消息/*for(JavaWebsocket item: webSocketSet){try {item.sendMessage("您好："+message);} catch (IOException e) {e.printStackTrace();continue;}}*///一对一单发消息try{JavaWebsocket ws = websocketMap.get(session);ws.sendMessage("您好："+message);}catch(Exception e){e.printStackTrace();}}/*** 发生错误时调用* @param session* @param error*/@OnErrorpublic void onError(Session session, Throwable error){System.out.println("发生错误");websocketMap.remove(session);error.printStackTrace();}/*** 这个方法与上面几个方法不一样。没有用注解，是根据自己需要添加的方法。* @param message* @throws IOException*/public void sendMessage(String message) throws IOException{this.session.getBasicRemote().sendText(message);//this.session.getAsyncRemote().sendText(message);}
}

3.页面

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<script type="text/javascript">var websocket = null;var host = window.location.host;//获取当前服务器ip:port//判断当前浏览器是否支持WebSocketif('WebSocket' in window){websocket = new WebSocket("ws://"+host+"/${basePath}/javaWebsocket");}else{alert('Not support websocket')}//连接发生错误的回调方法websocket.onerror = function(){setMessageInnerHTML("error");};//连接成功建立的回调方法websocket.onopen = function(event){setMessageInnerHTML("open");}//接收到消息的回调方法websocket.onmessage = function(event){setMessageInnerHTML(event.data);}//连接关闭的回调方法websocket.onclose = function(){setMessageInnerHTML("close");}//监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。window.onbeforeunload = function(){websocket.close();}//将消息显示在网页上function setMessageInnerHTML(innerHTML){document.getElementById('message').innerHTML += innerHTML + '<br/>';}//关闭连接function closeWebSocket(){websocket.close();}//发送消息function send(){var message = document.getElementById('text').value;websocket.send(message);}
</script>
<body>java websocket测试<br/><input id="text" type="text" /><button onclick="send()">Send</button><button onclick="closeWebSocket()">Close</button><div id="message"></div></body>
</html>

4.运行结果

二、spring websocket

1.下载spring-websocket包。maven下载与自己spring一致的版本

<!-- spring-websocket -->
<dependency><groupId>org.springframework</groupId><artifactId>spring-websocket</artifactId><version>4.3.9.RELEASE</version>
</dependency>

2.spring socket配置类

package com.ss.config;import com.ss.websocket.SpringWebSocket;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
import org.springframework.web.socket.handler.TextWebSocketHandler;
/*** spring websocket配置类*/
@Configuration
@EnableWebMvc
@EnableWebSocket
public class SpringWebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {//.setAllowedOrigins(sites);设置运行跨域，setAllowedOrigins("*"); *代表所有//设置允许跨域的站点String[] sites={"http://www.baidu.com","http://www.csdn.net"};//添加连接通道registry.addHandler(webSocketHandler(),"/websocket/springWebsocket").addInterceptors(new SpringWebSocketInterceptor()).setAllowedOrigins(sites);registry.addHandler(webSocketHandler(), "/sockjs/springWebsocket").addInterceptors(new SpringWebSocketInterceptor()).withSockJS();}@Beanpublic TextWebSocketHandler webSocketHandler(){return new SpringWebSocket();}
}

3.spring socket接收推送类

package com.ss.websocket;import com.ss.service.system.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
/*** spring socket接收推送类*/
public class SpringWebSocket extends TextWebSocketHandler {@Autowiredprivate UserService userService;private static Map<WebSocketSession, SpringWebSocket> websocketMap = new HashMap<>();public SpringWebSocket() {}/*** 连接成功时候，会触发页面上onopen方法*/public void afterConnectionEstablished(WebSocketSession session) throws Exception {websocketMap.put(session, this);System.out.println("connect to the websocket success......当前在线数量:" + websocketMap.size());//这块会实现自己业务，比如，当用户登录后，会把离线消息推送给用户//TextMessage returnMessage = new TextMessage("你将收到的离线");//session.sendMessage(returnMessage);}/*** 关闭连接时触发*/public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {System.out.println("用户" + session.getId() + "已退出！");websocketMap.remove(session);System.out.println("剩余在线用户" + websocketMap.size());}/*** js调用websocket.send时候，会调用该方法*/@Overrideprotected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {System.out.println(session.getId() + "发来消息：" + message);websocketMap.get(session).sendMessageToUser(session,message);super.handleTextMessage(session, message);}public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {if (session.isOpen()) {session.close();}websocketMap.remove(session);}public boolean supportsPartialMessages() {return false;}/*** 给某个用户发送消息** @param session* @param message*/public void sendMessageToUser(WebSocketSession session, TextMessage message) {int cc = userService.getUserCount(0,null);System.out.println("数据库用户数"+cc);System.out.println("--"+message.getPayload());WebSocketMessage msg = new TextMessage("您好:"+message.getPayload());try {if (session.isOpen()) {session.sendMessage(msg);}} catch (IOException e) {e.printStackTrace();}}/*** 给所有在线用户发送消息** @param message*/public void sendMessageToAllUser(TextMessage message) {Set<WebSocketSession> ks = websocketMap.keySet();for (WebSocketSession key : ks) {try {if (key.isOpen()) {key.sendMessage(message);}} catch (IOException e) {e.printStackTrace();}}}
}

4.spring websocket拦截器

package com.ss.config;import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor;
import javax.servlet.http.HttpSession;
import java.util.Map;
/***  spring WebSocket拦截器**/
public class SpringWebSocketInterceptor extends HttpSessionHandshakeInterceptor {@Overridepublic boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler,Map<String, Object> attributes) throws Exception {//只在页面初始化打开连接时调用System.out.println("spring WebSocket拦截器 ...Before Handshake");return super.beforeHandshake(request, response, wsHandler, attributes);}@Overridepublic void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler,Exception ex) {super.afterHandshake(request, response, wsHandler, ex);}
}

5.把拦截器加入spring配置中

导入websocket标签

xmlns:websocket="http://www.springframework.org/schema/websocket
http://www.springframework.org/schema/websocket
http://www.springframework.org/schema/websocket/spring-websocket.xsd

配置拦截器

<!--  spring socket拦截器-->
<bean id="springWebocketHandler" class="com.ss.websocket.SpringWebSocket"/>
<bean id="springWebocketInterceptor" class="com.ss.config.SpringWebSocketInterceptor"/>
<websocket:handlers ><websocket:mapping path="/websocket" handler="springWebocketHandler"/><websocket:handshake-interceptors><ref bean="springWebocketInterceptor"/></websocket:handshake-interceptors>
</websocket:handlers>

6.页面

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title><script type="text/javascript" src="${basePath}/static/js/jquery-1.11.0.min.js"></script><script type="text/javascript" src="${basePath}/static/js/reconnecting-websocket.min.js"></script><script type="text/javascript" src="${basePath}/static/js/sockjs-1.15.min.js"></script>
</head>
<script>var host = window.location.host;//获取当前服务器ip:portconsole.log(host);var websocket = null;if ('WebSocket' in window) {websocket = new WebSocket("ws://"+host+"/app/websocket/springWebsocket");//websocket = new ReconnectingWebSocket("ws://"+ host + "/app/websocket/springWebsocket", null, {debug:true, maxReconnectAttempts:4});}else if ('MozWebSocket' in window) {websocket = new MozWebSocket("ws://"+host+"/app/websocket/springWebsocket");}else {websocket = new SockJS("http://"+host+"/app/sockjs/springWebsocket");}//连接发生错误的回调方法websocket.onerror = function(){setMessageInnerHTML("error");};//连接成功建立的回调方法websocket.onopen = function(event){setMessageInnerHTML("open");}//接收到消息的回调方法websocket.onmessage = function(event){setMessageInnerHTML(event.data);}//连接关闭的回调方法websocket.onclose = function(){setMessageInnerHTML("close");}//监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。window.onbeforeunload = function(){websocket.close();}//将消息显示在网页上function setMessageInnerHTML(innerHTML){document.getElementById('message').innerHTML += innerHTML + '<br/>';}//关闭连接function closeWebSocket(){websocket.close();}//发送消息function send(){var message = document.getElementById('text').value;websocket.send(message);}
</script>
<body>spring websocket测试<br/><input id="text" type="text" /><button onclick="send()">Send</button><button onclick="closeWebSocket()">Close</button><div id="message"></div>
</body>
</html>