本文主要有三個步驟
1、用戶登錄後建立websocket連接，默認選擇websocket連接，如果瀏覽器不支持，則使用sockjs進行模擬連接
2、建立連接後，服務端返回該用戶的未讀消息
3、服務端進行相關操作後，推送給某一個用戶或者所有用戶新消息相關環境Spring4.0.6(要選擇4.0+),tomcat7.0.55
Websocet服務端實現
WebSocketConfig.java
@Configuration@EnableWebMvc@EnableWebSocketpublic class WebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {@Overridepublic void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {registry.addHandler(systemWebSocketHandler(),"/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor());registry.addHandler(systemWebSocketHandler(), "/sockjs/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor()).withSockJS();}@Beanpublic WebSocketHandler systemWebSocketHandler(){return new SystemWebSocketHandler();}}不要忘記在springmvc的配置文件中配置對此類的自動掃描
<context:component-scan base-package="com.ldl.origami.websocket" />
@Configuration
@EnableWebMvc
@EnableWebSocket
這三個大致意思是使這個類支持以@Bean的方式加載bean，並且支持springmvc和websocket，不是很準確大致這樣，試了一下@EnableWebMvc不加也沒什麼影響，@Configuration本來就支持springmvc的自動掃描
registry.addHandler(systemWebSocketHandler(),"/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor())
用來註冊websocket server實現類，第二個參數是訪問websocket的地址
registry.addHandler(systemWebSocketHandler(), "/sockjs/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor()).withSockJS();}
這個是使用Sockjs的註冊方法
首先SystemWebSocketHandler.java
public class SystemWebSocketHandler implements WebSocketHandler {private static final Logger logger;private static final ArrayList<WebSocketSession> users;static {users = new ArrayList<>();logger = LoggerFactory.getLogger(SystemWebSocketHandler.class);}@Autowiredprivate WebSocketService webSocketService;@Overridepublic void afterConnectionEstablished(WebSocketSession session) throws Exception {logger.debug("connect to the websocket success......");users.add(session);String userName = (String) session.getAttributes().get(Constants.WEBSOCKET_USERNAME);if(userName!= null){//查詢未讀消息int count = webSocketService.getUnReadNews((String) session.getAttributes().get(Constants.WEBSOCKET_USERNAME));session.sendMessage(new TextMessage(count + ""));}}@Overridepublic void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception {//sendMessageToUsers();}@Overridepublic void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {if(session.isOpen()){session.close();}logger.debug("websocket connection closed......");users.remove(session);}@Overridepublic void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {logger.debug("websocket connection closed......");users.remove(session);}@Overridepublic boolean supportsPartialMessages() {return false;}/*** 給所有在線用戶發送消息** @param message*/public void sendMessageToUsers(TextMessage message) {for (WebSocketSession user : users) {try {if (user.isOpen()) {user.sendMessage(message);}} catch (IOException e) {e.printStackTrace();}}}/*** 給某個用戶發送消息** @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;}}}}相關內容大家一看就能明白，就不多解釋了
然後WebSocketHandshakeInterceptor.java
public class WebSocketHandshakeInterceptor implements HandshakeInterceptor {private static Logger logger = LoggerFactory.getLogger(HandshakeInterceptor.class);@Overridepublic boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object> attributes) throws Exception {if (request instanceof ServletServerHttpRequest) {ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) request;HttpSession session = servletRequest.getServletRequest().getSession(false);if (session != null) {//使用userName區分WebSocketHandler，以便定向發送消息String userName = (String) session.getAttribute(Constants.SESSION_USERNAME);attributes.put(Constants.WEBSOCKET_USERNAME,userName);}}return true;}@Overridepublic void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception exception) {}}這個的主要作用是取得當前請求中的用戶名，並且保存到當前的WebSocketHandler中，以便確定WebSocketHandler所對應的用戶，具體可參考HttpSessionHandshakeInterceptor
用戶登錄建立websocket連接
index.jsp
<script type="text/javascript" src="http://localhost:8080/Origami/websocket/sockjs-0.3.min.js"></script><script>var websocket;if ('WebSocket' in window) {websocket = new WebSocket("ws://localhost:8080/Origami/webSocketServer");} else if ('MozWebSocket' in window) {websocket = new MozWebSocket("ws://localhost:8080/Origami/webSocketServer");} else {websocket = new SockJS("http://localhost:8080/Origami/sockjs/webSocketServer");}websocket.onopen = function (evnt) {};websocket.onmessage = function (evnt) {$("#msgcount").html("(<font color='red'>"+evnt.data+"</font>)")};websocket.onerror = function (evnt) {};websocket.onclose = function (evnt) {}</script>使用sockjs時要注意
1、這兩個的寫法
<script type="text/javascript" src="http://localhost:8080/Origami/websocket/sockjs-0.3.min.js"></script>websocket = new SockJS(http://localhost:8080/Origami/sockjs/webSocketServer);
2、web.xml中
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_1.xsd">
version
web-app_3_1.xsd
這兩個的版本都要是3.0+
然後在這個servlet中加入
<async-supported>true</async-supported><servlet><servlet-name>appServlet</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><init-param><param-name>contextConfigLocation</param-name><param-value>classpath*:servlet-context.xml</param-value></init-param><load-on-startup>1</load-on-startup><async-supported>true</async-supported></servlet>
然後所有的filter中也加入
<async-supported>true</async-supported>
3、添加相關依賴
<dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-annotations</artifactId><version>2.3.0</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-core</artifactId><version>2.3.1</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.3.3</version></dependency>
好了，現在websocket可以正常建立起來了
返回用戶未讀的消息
當連接建立後，會進入SystemWebSocketHandler的afterConnectionEstablished方法，代碼看上邊，取出WebSocketHandshakeInterceptor中保存的用戶名
查詢信息後使用session.sendMessage(new TextMessage(count + ""));返回給用戶，從哪來回哪去
服務端推送消息給用戶
@Controllerpublic class AdminController {static Logger logger = LoggerFactory.getLogger(AdminController.class);@Autowired(required = false)private AdminService adminService;@Beanpublic SystemWebSocketHandler systemWebSocketHandler() {return new SystemWebSocketHandler();}@RequestMapping("/auditing")@ResponseBodypublic String auditing(HttpServletRequest request){//無關代碼都省略了int unReadNewsCount = adminService.getUnReadNews(username);systemWebSocketHandler().sendMessageToUser(username, new TextMessage(unReadNewsCount + ""));return result;}}在這裡可以使用sendMessageToUser給某個用戶推送信息，也可以使用sendMessageToUsers給所有用戶推送信息