一、介绍
1.两种方式，一种使用tomcat的websocket实现，一种使用spring的websocket
2.tomcat的方式需要tomcat 7.x，JEE7的支持。
3.spring与websocket整合需要spring 4.x，并且使用了socketjs，对不支持websocket的浏览器可以模拟websocket使用
二、方式一：tomcat
使用这种方式无需别的任何配置，只需服务端一个处理类，
服务器端代码
package com.Socket; import java.io.IOException; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; import javax.websocket.*; import javax.websocket.server.PathParam; import javax.websocket.server.ServerEndpoint; import net.sf.json.JSONObject; @ServerEndpoint("/websocket/{username}") public class WebSocket { private static int onlineCount = 0; private static Map<String, WebSocket> clients = new ConcurrentHashMap<String, WebSocket>(); private Session session; private String username; @OnOpen public void onOpen(@PathParam("username") String username, Session session) throws IOException { this.username = username; this.session = session; addOnlineCount(); clients.put(username, this); System.out.println("已连接"); } @OnClose public void onClose() throws IOException { clients.remove(username); subOnlineCount(); } @OnMessage public void onMessage(String message) throws IOException { JSONObject jsonTo = JSONObject.fromObject(message); if (!jsonTo.get("To").equals("All")){ sendMessageTo("给一个人", jsonTo.get("To").toString()); }else{ sendMessageAll("给所有人"); } } @OnError public void onError(Session session, Throwable error) { error.printStackTrace(); } public void sendMessageTo(String message, String To) throws IOException { // session.getBasicRemote().sendText(message); //session.getAsyncRemote().sendText(message); for (WebSocket item : clients.values()) { if (item.username.equals(To) ) item.session.getAsyncRemote().sendText(message); } } public void sendMessageAll(String message) throws IOException { for (WebSocket item : clients.values()) { item.session.getAsyncRemote().sendText(message); } } public static synchronized int getOnlineCount() { return onlineCount; } public static synchronized void addOnlineCount() { WebSocket.onlineCount++; } public static synchronized void subOnlineCount() { WebSocket.onlineCount--; } public static synchronized Map<String, WebSocket> getClients() { return clients; } } 客户端js
var websocket = null; var username = localStorage.getItem("name"); //判断当前浏览器是否支持WebSocket if ('WebSocket' in window) { websocket = new WebSocket("ws://" + document.location.host + "/WebChat/websocket/" + username + "/"+ _img); } else { alert('当前浏览器 Not support websocket') } //连接发生错误的回调方法 websocket.onerror = function() { setMessageInnerHTML("WebSocket连接发生错误"); }; //连接成功建立的回调方法 websocket.onopen = function() { setMessageInnerHTML("WebSocket连接成功"); } //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("WebSocket连接关闭"); } //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() { closeWebSocket(); } //关闭WebSocket连接 function closeWebSocket() { websocket.close(); } 发送消息只需要使用websocket.send(“发送消息”)，就可以触发服务端的onMessage()方法，当连接时，触发服务器端onOpen()方法，此时也可以调用发送消息的方法去发送消息。关闭websocket时，触发服务器端onclose()方法，此时也可以发送消息，但是不能发送给自己，因为自己的已经关闭了连接，但是可以发送给其他人。
三、方法二：spring整合
WebSocketConfig.java
这个类是配置类，所以需要在spring mvc配置文件中加入对这个类的扫描，第一个addHandler是对正常连接的配置，第二个是如果浏览器不支持websocket，使用socketjs模拟websocket的连接。
package com.websocket; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; 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; @Configuration @EnableWebSocket public class WebSocketConfig implements WebSocketConfigurer { @Override public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) { registry.addHandler(chatMessageHandler(),"/webSocketServer").addInterceptors(new ChatHandshakeInterceptor()); registry.addHandler(chatMessageHandler(), "/sockjs/webSocketServer").addInterceptors(new ChatHandshakeInterceptor()).withSockJS(); } @Bean public TextWebSocketHandler chatMessageHandler(){ return new ChatMessageHandler(); } } ChatHandshakeInterceptor.java
这个类的作用就是在连接成功前和成功后增加一些额外的功能，Constants.java类是一个工具类，两个常量。
package com.websocket; import java.util.Map; import org.apache.shiro.SecurityUtils; import org.springframework.http.server.ServerHttpRequest; import org.springframework.http.server.ServerHttpResponse; import org.springframework.web.socket.WebSocketHandler; import org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor; public class ChatHandshakeInterceptor extends HttpSessionHandshakeInterceptor { @Override public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object> attributes) throws Exception { System.out.println("Before Handshake"); /* * if (request instanceof ServletServerHttpRequest) { * ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) * request; HttpSession session = * servletRequest.getServletRequest().getSession(false); if (session != * null) { //使用userName区分WebSocketHandler，以便定向发送消息 String userName = * (String) session.getAttribute(Constants.SESSION_USERNAME); if * (userName==null) { userName="default-system"; } * attributes.put(Constants.WEBSOCKET_USERNAME,userName); * * } } */ //使用userName区分WebSocketHandler，以便定向发送消息(使用shiro获取session,或是使用上面的方式) String userName = (String) SecurityUtils.getSubject().getSession().getAttribute(Constants.SESSION_USERNAME); if (userName == null) { userName = "default-system"; } attributes.put(Constants.WEBSOCKET_USERNAME, userName); return super.beforeHandshake(request, response, wsHandler, attributes); } @Override public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception ex) { System.out.println("After Handshake"); super.afterHandshake(request, response, wsHandler, ex); } } ChatMessageHandler.java
这个类是对消息的一些处理，比如是发给一个人，还是发给所有人，并且前端连接时触发的一些动作
package com.websocket; import java.io.IOException; import java.util.ArrayList; import org.apache.log4j.Logger; import org.springframework.web.socket.CloseStatus; import org.springframework.web.socket.TextMessage; import org.springframework.web.socket.WebSocketSession; import org.springframework.web.socket.handler.TextWebSocketHandler; public class ChatMessageHandler extends TextWebSocketHandler { private static final ArrayList<WebSocketSession> users;// 这个会出现性能问题，最好用Map来存储，key用userid private static Logger logger = Logger.getLogger(ChatMessageHandler.class); static { users = new ArrayList<WebSocketSession>(); } /** * 连接成功时候，会触发UI上onopen方法 */ @Override public void afterConnectionEstablished(WebSocketSession session) throws Exception { System.out.println("connect to the websocket success......"); users.add(session); // 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); } /** * 在UI在用js调用websocket.send()时候，会调用该方法 */ @Override protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception { sendMessageToUsers(message); //super.handleTextMessage(session, message); } /** * 给某个用户发送消息 * * @param userName * @param message */ public void sendMessageToUser(String userName, TextMessage message) { for (WebSocketSession user : users) { if (user.getAttributes().get(Constants.WEBSOCKET_USERNAME).equals(userName)) { try { if (user.isOpen()) { user.sendMessage(message); } } catch (IOException e) { e.printStackTrace(); } break; } } } /** * 给所有在线用户发送消息 * * @param message */ public void sendMessageToUsers(TextMessage message) { for (WebSocketSession user : users) { try { if (user.isOpen()) { user.sendMessage(message); } } catch (IOException e) { e.printStackTrace(); } } } @Override public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception { if (session.isOpen()) { session.close(); } logger.debug("websocket connection closed......"); users.remove(session); } @Override public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception { logger.debug("websocket connection closed......"); users.remove(session); } @Override public boolean supportsPartialMessages() { return false; } } spring-mvc.xml
正常的配置文件，同时需要增加对WebSocketConfig.java类的扫描，并且增加
xmlns:websocket="http://www.springframework.org/schema/websocket" http://www.springframework.org/schema/websocket <a target="_blank" href="http://www.springframework.org/schema/websocket/spring-websocket-4.1.xsd" rel="external nofollow" >http://www.springframework.org/schema/websocket/spring-websocket-4.1.xsd</a>
客户端
<script type="text/javascript" src="http://localhost:8080/Bank/js/sockjs-0.3.min.js"></script> <script> var websocket; if ('WebSocket' in window) { websocket = new WebSocket("ws://" + document.location.host + "/Bank/webSocketServer"); } else if ('MozWebSocket' in window) { websocket = new MozWebSocket("ws://" + document.location.host + "/Bank/webSocketServer"); } else { websocket = new SockJS("http://" + document.location.host + "/Bank/sockjs/webSocketServer"); } websocket.onopen = function(evnt) {}; websocket.onmessage = function(evnt) { $("#test").html("(<font color='red'>" + evnt.data + "</font>)") }; websocket.onerror = function(evnt) {}; websocket.onclose = function(evnt) {} $('#btn').on('click', function() { if (websocket.readyState == websocket.OPEN) { var msg = $('#id').val(); //调用后台handleTextMessage方法 websocket.send(msg); } else { alert("连接失败!"); } }); </script> 注意导入socketjs时要使用地址全称，并且连接使用的是http而不是websocket的ws
总结
以上所述是小编给大家介绍的java 实现websocket的两种方式实例详解，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对VeVb武林网网站的支持！
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