java tomcat的websocket

刺骨的言语ヽ痛彻心扉 2022-05-19 01:27 132阅读 0赞

普通servlet方式和spring方式实现websocket

1.  普通servlet，依赖如下
    
    1.      <dependency>
                  <groupId>javax.websocket</groupId>
                  <artifactId>javax.websocket-api</artifactId>
                  <version>1.1</version>
                  <scope>provided</scope>
                </dependency>
               
            <dependency>
                  <groupId>javax.servlet</groupId>
                  <artifactId>javax.servlet-api</artifactId>
                  <version>3.1.0</version>
                  <scope>provided</scope>
                </dependency>
            
                
                
                <dependency>
                  <groupId>javax.servlet.jsp</groupId>
                  <artifactId>javax.servlet.jsp-api</artifactId>
                  <version>2.3.1</version>
                  <scope>provided</scope>
                </dependency>

服务器端创建：

@ServerEndpoint("/chat")
    public class EchoEndpoint {
        private static int onlineCount = 0;
        private static CopyOnWriteArraySet<EchoEndpoint> webSocketSet = new CopyOnWriteArraySet<EchoEndpoint>();
        private Session session;
    
        synchronized void  addOnlineCount(){
            onlineCount++;
        }
        int getOnlineCount(){
             return onlineCount;
        }
       synchronized void subOnlineCount(){
           onlineCount--;
        }
    
        @OnOpen
        public void onOpen(Session session){
            this.session = session;
            webSocketSet.add(this);     //加入set中
            addOnlineCount();           //在线数加1
            System.out.println("有新连接加入！当前在线人数为" + getOnlineCount());
        }
    
        @OnClose
        public void onClose(){
            webSocketSet.remove(this);  //从set中删除
            subOnlineCount();           //在线数减1
            System.out.println("有一连接关闭！当前在线人数为" + getOnlineCount());
        }
    
        @OnMessage
        public void onMessage(String message, Session session) {
            System.out.println("来自客户端的消息:" + message);
            //群发消息
            for(EchoEndpoint item: webSocketSet){
                try {
                    item.sendMessage(message);
                } catch (IOException e) {
                    e.printStackTrace();
                    continue;
                }
            }
        }
    
        @OnError
        public void onError(Session session, Throwable error){
            System.out.println("发生错误");
            error.printStackTrace();
        }
    
        public void sendMessage(String message) throws IOException{
            this.session.getBasicRemote().sendText(message);
        }
    
    }

注意注解也是不能少的。

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
    <%
        String path = request.getContextPath();
        String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
    %>
    
    <!DOCTYPE HTML>
    <html>
    <head>
        <script src="http://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script>
    
        <base href="<%=basePath%>">
        <title>My WebSocket</title>
    </head>
    
    <body>
    Welcome<br/>
    <input id="text" type="text" />
    <button id="login" >登录</button>
    <button id="send" onclick="send()">发送</button>
    <button id="close" onclick="closeWebSocket()">关闭</button>
    <div id="message">
    </div>
    </body>
    
    <script type="text/javascript">
        var websocket = null;
    
        //判断当前浏览器是否支持WebSocket
        if('WebSocket' in window){
            $("#login").click(function(){
                websocket = new WebSocket("ws://localhost:80/chat");
    
                //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");
                    $("#login").hide(); //隐藏登录按钮
                };
    
                //接收到消息的回调方法
                websocket.onmessage = function(){
                    setMessageInnerHTML(event.data);
                };
    
                //连接关闭的回调方法
                websocket.onclose = function(){
                    setMessageInnerHTML("close");
                    $("#login").show(); //显示登录按钮
                    $("#send").hide(); //显示登录按钮
                    $("#close").hide(); //显示登录按钮
    
                };
    
            });
        }
        else{
            alert('Not support websocket');
        }
    
    
    
        //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>
    </html>

页面如上。不需要配置web.xml也没有其他配置，启动服务器就可以了。

2.springWebsocket

<dependency>
          <groupId>javax.servlet</groupId>
          <artifactId>javax.servlet-api</artifactId>
          <version>3.1.0</version>
          <scope>provided</scope>
        </dependency>
    
        
        
        <dependency>
          <groupId>javax.servlet.jsp</groupId>
          <artifactId>javax.servlet.jsp-api</artifactId>
          <version>2.3.1</version>
          <scope>provided</scope>
        </dependency>
    
        
        <dependency>
          <groupId>javax.websocket</groupId>
          <artifactId>javax.websocket-api</artifactId>
          <version>1.1</version>
          <scope>provided</scope>
        </dependency>
    
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-websocket</artifactId>
          <version>4.3.18.RELEASE</version>
        </dependency>
        
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-webmvc</artifactId>
          <version>4.3.18.RELEASE</version>
        </dependency>

配置文件：

<servlet>
            <servlet-name>mvc</servlet-name>
            <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
            <load-on-startup>1</load-on-startup>
        </servlet>
        <servlet-mapping>
             <servlet-name>mvc</servlet-name>
            <url-pattern>/</url-pattern>
        </servlet-mapping>

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
    http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    
        <mvc:annotation-driven></mvc:annotation-driven>
        <context:component-scan base-package="Springsocket"></context:component-scan>
        <context:annotation-config />
    
         <bean
          class="org.springframework.web.servlet.view.InternalResourceViewResolver"
         id="internalResourceViewResolver">
            
           <property name="prefix" value="/WEB-INF/jsp/" />
           
           <property name="suffix" value=".jsp" />
       </bean>
    
    </beans>

写一个类集成此类，方法名字写的很形象：

public class WebSocketHandler extends TextWebSocketHandler {
    
        //用于保存连接的用户
        private List<WebSocketSession>list =new ArrayList<WebSocketSession>();
    
    
        @Override //连接创建完成的意思吗
        public void afterConnectionEstablished(WebSocketSession session) throws Exception {
            System.out.println("一位客户连接上来");
            list.add(session);
        }
    
        @Override //处理text消息
        protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
            System.out.println("收到消息："+message);
            for (WebSocketSession webSocketSession : list) {
                webSocketSession.sendMessage(message);
            }
    
        }
    
        @Override //发生错误的意思吗
        public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
            list.remove(session);
            System.out.println("出错");
            exception.printStackTrace();
        }
    
        @Override  //连接关闭
        public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
            list.remove(session);
            System.out.println("连接关闭");
        }
    
    
    }

写一个配置类，将上面的handler类注册进去，注意注解：

@Configuration
    @EnableWebSocket
    public class WebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {
    
        @Override
        public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
            String url ="/socket";
            registry.addHandler(webSocketHandler(),url);
    
        }
    
        @Bean
    public TextWebSocketHandler webSocketHandler(){
            return new WebSocketHandler();
    }
    
    }

index.jsp上面修改这个地址：

![70][]

启动服务器即可。

其他，websocket连接还可以添加拦截器，方法是：

写一个类实现此接口：

public class WebSocketHandshakeInterceptor implements HandshakeInterceptor {
    
    
        @Override //之前
        public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object> attributes) throws Exception {
            return false;
        }
    
        @Override //之后
        public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception exception) {
    
        }
    }

在上面配置handler时顺便配置拦截器即可：

@Configuration
    @EnableWebSocket
    public class WebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {
    
        @Override
        public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
            String url ="/socket";
            registry.addHandler(webSocketHandler(),url).addInterceptors(handshakeInterceptor());
    
        }
    
        @Bean
    public TextWebSocketHandler webSocketHandler(){
            return new WebSocketHandler();
    }
        @Bean
    public HandshakeInterceptor handshakeInterceptor(){
            return new WebSocketHandshakeInterceptor();
    }
    
    }

[70]: /images/20220519/b4a9790a7241457ea5ee9d671f158c6d.png