Spring boot项目整合WebSocket方法-编程学习网

WebSocket是一种在单个TCP连接上进行全双工通信的协议。WebSocket通信协议于2011年被IETF定为标准RFC 6455，并由RFC7936补充规范。WebSocket API也被W3C定为标准。WebSocket使得客户端和服务器之间的数据交换变得更加简单，允许服务端主动向客户端推送数据。在WebSocket API中，浏览器和服务器只需要完成一次握手，两者之间就直接可以创建持久性的连接，并进行双向数据传输。

springboot对websocket支持很友好,只需要继承webSocketHandler类,重写几个方法就可以了

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



@Service
public class CustomWebSocketHandler extends TextWebSocketHandler implements WebSocketHandler {
    private Logger logger = LoggerFactory.getLogger(CustomWebSocketHandler.class);
    // 在线用户列表
    private static final Map<String, WebSocketSession> users;
    // 用户标识
    private static final aString CLIENT_ID = "mchNo";

    static {
        users = new HashMap<>();
    }

    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        logger.info("成功建立websocket-spring连接");
        String mchNo = getMchNo(session);
        if (StringUtils.isNotEmpty(mchNo)) {
            users.put(mchNo, session);
            session.sendMessage(new TextMessage("成功建立websocket-spring连接"));
            logger.info("用户标识：{}，Session：{}", mchNo, session.toString());
        }
    }

    @Override
    public void handleTextMessage(WebSocketSession session, TextMessage message) {
        logger.info("收到客户端消息：{}", message.getPayload());
        JSONObject msgJson = JSONObject.parseObject(message.getPayload());
        String to = msgJson.getString("to");
        String msg = msgJson.getString("msg");
        WebSocketMessage<?> webSocketMessageServer = new TextMessage("server:" +message);
        try {
            session.sendMessage(webSocketMessageServer);
            if("all".equals(to.toLowerCase())) {
                sendMessageToAllUsers(new TextMessage(getMchNo(session) + ":" +msg));
            }else {
                sendMessageToUser(to, new TextMessage(getMchNo(session) + ":" +msg));
            }
        } catch (IOException e) {
            logger.info("handleTextMessage method error：{}", e);
        }
    }

    @Override
    public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
        if (session.isOpen()) {
            session.close();
        }
        logger.info("连接出错");
        users.remove(getMchNo(session));
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
        logger.info("连接已关闭：" + status);
        users.remove(getMchNo(session));
    }

    @Override
    public boolean supportsPartialMessages() {
        return false;
    }

    public void sendMessage(String jsonData) {
        logger.info("收到客户端消息sendMessage：{}", jsonData);
        JSONObject msgJson = JSONObject.parseObject(jsonData);
        String mchNo = StringUtils.isEmpty(msgJson.getString(CLIENT_ID)) ? "陌生人" : msgJson.getString(CLIENT_ID);
        String to = msgJson.getString("to");
        String msg = msgJson.getString("msg");
        if("all".equals(to.toLowerCase())) {
            sendMessageToAllUsers(new TextMessage(mchNo + ":" +msg));
        }else {
            sendMessageToUser(to, new TextMessage(mchNo + ":" +msg));
        }
    }
    
    
    public boolean sendMessageToUser(String mchNo, TextMessage message) {
        if (users.get(mchNo) == null)
            return false;
        WebSocketSession session = users.get(mchNo);
        logger.info("sendMessage：{} ,msg：{}", session, message.getPayload());
        if (!session.isOpen()) {
            logger.info("客户端:{},已断开连接，发送消息失败", mchNo);
            return false;
        }
        try {
            session.sendMessage(message);
        } catch (IOException e) {
            logger.info("sendMessageToUser method error：{}", e);
            return false;
        }
        return true;
    }

    
    public boolean sendMessageToAllUsers(TextMessage message) {
        boolean allSendSuccess = true;
        Set<String> mchNos = users.keySet();
        WebSocketSession session = null;
        for (String mchNo : mchNos) {
            try {
                session = users.get(mchNo);
                if (session.isOpen()) {
                    session.sendMessage(message);
                }else {
                    logger.info("客户端:{},已断开连接，发送消息失败", mchNo);
                }
            } catch (IOException e) {
                logger.info("sendMessageToAllUsers method error：{}", e);
                allSendSuccess = false;
            }
        }

        return allSendSuccess;
    }
    
    
    private String getMchNo(WebSocketSession session) {
        try {
            String mchNo = session.getAttributes().get(CLIENT_ID).toString();
            return mchNo;
        } catch (Exception e) {
            return null;
        }
    }
}

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

我们希望能够把websocketSession和httpsession对应起来，这样就能根据当前不同的session，定向对websocketSession进行数据返回;在查询资料之后，发现spring中有一个拦截器接口，HandshakeInterceptor，可以实现这个接口，来拦截握手过程，向其中添加属性



public class CustomWebSocketInterceptor implements HandshakeInterceptor {
    private Logger logger = LoggerFactory.getLogger(CustomWebSocketInterceptor.class);
    
    @Override
    public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler handler, Map<String, Object> map) throws Exception {
        if (request instanceof ServletServerHttpRequest) {
            logger.info("*****beforeHandshake******");
            HttpServletRequest httpServletRequest = ((ServletServerHttpRequest) request).getServletRequest();
            HttpSession session = httpServletRequest.getSession(true);
            
            logger.info("mchNo：{}", httpServletRequest.getParameter("mchNo"));
            if (session != null) {
                
                map.put("sessionId",session.getId());
                map.put("mchNo", httpServletRequest.getParameter("mchNo"));
            }
        }
        return true;
    }

    @Override
    public void afterHandshake(ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse, WebSocketHandler webSocketHandler, Exception e) {
        logger.info("******afterHandshake******");
    }
}

这个类是配置类向Spring中注入handler



@Configuration
@EnableWebSocket
public class CustomWebSocketConfig implements WebSocketConfigurer {

    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(customWebSocketHandler(), "/webSocketBySpring/customWebSocketHandler").addInterceptors(new CustomWebSocketInterceptor()).setAllowedOrigins("*");
        registry.addHandler(customWebSocketHandler(), "/sockjs/webSocketBySpring/customWebSocketHandler").addInterceptors(new CustomWebSocketInterceptor()).setAllowedOrigins("*").withSockJS();
    }

    @Bean
    public WebSocketHandler customWebSocketHandler() {
        return new CustomWebSocketHandler();
    }
}

补充说明：

setAllowedOrigins("*")一定要加上，不然只有访问localhost，其他的不予许访问

setAllowedOrigins(String[] domains),允许指定的域名或IP(含端口号)建立长连接，如果只允许自家域名访问，这里轻松设置。如果不限时使用"*"号，如果指定了域名，则必须要以http或https开头

经查阅官方文档springwebsocket 4.1.5版本前默认支持跨域访问，之后的版本默认不支持跨域，需要设置

使用withSockJS()的原因：

　　一些浏览器中缺少对WebSocket的支持,因此，回退选项是必要的，而Spring框架提供了基于SockJS协议的透明的回退选项。

SockJS的一大好处在于提供了浏览器兼容性。优先使用原生WebSocket，如果在不支持websocket的浏览器中，会自动降为轮询的方式。
除此之外，spring也对socketJS提供了支持。

如果代码中添加了withSockJS()如下，服务器也会自动降级为轮询。

registry.addEndpoint("/coordination").withSockJS();

SockJS的目标是让应用程序使用WebSocket API，但在运行时需要在必要时返回到非WebSocket替代，即无需更改应用程序代码。

客户端与JAVA WebSocket建立连接


<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt"%>
<c:set var="ctx" value="${pageContext.request.contextPath}" />
<c:set var="ctxpath"
    value="${pageContext.request.scheme}${'://'}${pageContext.request.serverName}${':'}${pageContext.request.serverPort}${pageContext.request.contextPath}" />
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta charset=UTF-8">
<title>登录测试</title>
</head>
<body>
    <h2>Hello World! Web Socket by Spring</h2>
    <div>
        <span>sessionId:</span>
        <% 
            HttpSession s= request.getSession(); 
            out.println(s.getId());
        %>
    </div>
    
    <input id="sessionId" type="hidden" value="<%=session.getId() %>" />
    <input id="text" type="text" />
    <button onclick="send()">发送消息</button>
    <hr />
    <button onclick="closeWebSocket()">关闭WebSocket连接</button>
    <hr />
    <div id="message"></div>
</body>
<script type="text/javascript" src="http://localhost:8088/static/js/sockjs-0.3.min.js"></script>
<script type="text/javascript">  
        var websocket = null;  
        //判断当前浏览器是否支持WebSocket  
        //判断当前浏览器是否支持WebSocket  
        if('WebSocket' in window) {
            websocket = new WebSocket("ws://localhost:8088/websocket/webSocketBySpring/customWebSocketHandler?mchNo="+ 123);  
        } else if('MozWebSocket' in window) {
            websocket = new MozWebSocket("ws://localhost:8088/websocket/webSocketBySpring/customWebSocketHandler?mchNo="+ 123);
        } else {
            websocket = new SockJS("http://localhost:8088/websocket/sockjs/webSocketBySpring/customWebSocketHandler?mchNo="+ 123);
        }
        //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();  
        }  
      
        //将消息显示在网页上  
        function setMessageInnerHTML(innerHTML) {  
            document.getElementById('message').innerHTML += innerHTML + '<br/>';  
        }  
      
        //关闭WebSocket连接  
        function closeWebSocket() {  
            websocket.close();  
        }  
      
        //发送消息  
        function send() {  
            var message = document.getElementById('text').value;  
            websocket.send(message);  
        }  
    </script>
</html>

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文章详情

Spring boot项目整合WebSocket方法

补充说明：

使用withSockJS()的原因：

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