[网络协议]Spring WebSocket前后台推送入门

项目结构如下：

依赖文件：pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

  <modelVersion>4.0.0</modelVersion>
  <packaging>war</packaging>

  <name>WebSocketPro</name>
  <groupId>org.example</groupId>
  <artifactId>WebSocketPro</artifactId>
  <version>1.0-SNAPSHOT</version>

  <build>
    <plugins>
      <plugin>
        <groupId>org.mortbay.jetty</groupId>
        <artifactId>maven-jetty-plugin</artifactId>
        <version>6.1.7</version>
        <configuration>
          <connectors>
            <connector implementation="org.mortbay.jetty.nio.SelectChannelConnector">
              <port>8888</port>
              <maxIdleTime>30000</maxIdleTime>
            </connector>
          </connectors>
          <webAppSourceDirectory>${project.build.directory}/${pom.artifactId}-${pom.version}</webAppSourceDirectory>
          <contextPath>/</contextPath>
        </configuration>
      </plugin>
    </plugins>
  </build>

  <dependencies>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>4.1.5.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>jstl</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>
    <dependency>
      <groupId>taglibs</groupId>
      <artifactId>standard</artifactId>
      <version>1.1.2</version>
    </dependency>

    <!-- spring websocket -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-messaging</artifactId>
      <version>4.1.7.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-websocket</artifactId>
      <version>4.1.7.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>javax.websocket</groupId>
      <artifactId>javax.websocket-api</artifactId>
      <version>1.0</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>

</project>

spring-websoket.xml

<?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:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">


    <context:component-scan base-package="com.ithnhe.websocket"></context:component-scan>
    <!--静态资源不被过滤-->
    <mvc:default-servlet-handler/>

</beans>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
         xmlns="http://java.sun.com/xml/ns/j2ee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

  <servlet>
    <servlet-name>mvc-dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:spring-websoket.xml</param-value>
    </init-param>
  </servlet>

  <servlet-mapping>
    <servlet-name>mvc-dispatcher</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

</web-app>
        

?

websocket配置类：

package com.ithnhe.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;

@Configuration
@EnableWebSocket
public class MyWebsocketConfig implements WebSocketConfigurer {


    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(webSocketHandler(),"/websocket")
                .addInterceptors(new MyHandshakeInterceptor()).setAllowedOrigins("*");

        registry.addHandler(webSocketHandler(),"/sockjs/websocket")
                .addInterceptors(new MyHandshakeInterceptor()).withSockJS();
    }

    /**
     * websocket处理类
     * @return
     */
    @Bean
    public MyWebsocketHandler webSocketHandler(){
        return new MyWebsocketHandler();
    }

}

?

• registerWebSocketHandlers：这个方法是向spring容器注册一个handler地址，websocket的建立连接的地址就是xxxx/websocket
• addInterceptors：拦截器，当建立websocket连接的时候，我们可以通过继承spring的HttpSessionHandshakeInterceptor来做一些处理
• setAllowedOrigins：跨域设置，*表示所有域名都可以，不限制， 域包括ip：port, 指定*可以是任意的域名，不加的话默认localhost+本服务端口
• withSockJS： 这个是应对浏览器不支持websocket协议的时候降级为轮询的处理。

?创建拦截器：

package com.ithnhe.websocket;

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;

import java.util.Map;

public class MyHandshakeInterceptor extends HttpSessionHandshakeInterceptor {

    @Override
    public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object> attributes) throws Exception {
        System.out.println("beforeHandshake websoket.. ");
        return super.beforeHandshake(request, response, wsHandler, attributes);
    }

    @Override
    public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception ex) {
        System.out.println("afterHandshake websoket...");
        super.afterHandshake(request, response, wsHandler, ex);
    }
}

Handler类：

package com.ithnhe.websocket;

import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.WebSocketMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.AbstractWebSocketHandler;


/**
 * websoket 业务处理
 */
public class MyWebsocketHandler extends AbstractWebSocketHandler {

    public MyWebsocketHandler() {
    }

    /**
     * 连接成功后会执行该方法 会触发页面上的onopen方法
     * @param session
     * @throws Exception
     */
    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {

        System.out.println("建立websoket连接！");
    }

    /**
     *
     * @param session
     * @param message
     * @throws Exception
     */
    @Override
    public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception {

        String msg = message.getPayload().toString();
        System.out.println("服务器接收到信息="+msg);

        //处理其他业务
        //推送消息
        MessageThread messageThread = new MessageThread(session);
        Thread thread = new Thread(messageThread);
        thread.start();
    }

    @Override //关闭连接时触发该方法
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {

        System.out.println("关闭websoket连接！");
    }


}

MessageThread类：

package com.ithnhe.websocket;


import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;

import java.io.IOException;

public class MessageThread implements Runnable{

    public WebSocketSession session;
    public MessageThread(WebSocketSession session){
        this.session = session;

    }

    public void run() {

        if (session.isOpen()) {
            TextMessage textMessage = new TextMessage("good!");
            try {
                session.sendMessage(textMessage);

            } catch (IOException e) {
                e.printStackTrace();
            }
            System.out.println("socket数据推送成功！");

        } else {
            System.out.println("socket连接已经断开！");
        }

    }

}

index.jsp页面

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Charles-WebSocket</title>

    <script type="text/javascript">

        var websocket = null;
        var target = "ws://localhost:8080/WebSocketPro/websocket";

        function buildConnection() {

            if('WebSocket' in window) {
                websocket = new WebSocket(target);
            } else if('MozWebSocket' in window) {
                websocket = MozWebSocket(target);
            } else {
                window.alert("浏览器不支持WebSocket");
            }
        }

        // 往后台服务器发送消息.
        function sendMessage() {

            var sendmsg = document.getElementById("sendMsg").value;
            console.log("发送的消息：" + sendmsg);

            // 发送至后台服务器中.
            websocket.send(sendmsg);

            //获取后台推送的数据
            websocket.onmessage = function (e) {
                console.log("接收的消息：" + e.data);
            };


        }



    </script>
</head>
<body>

<button onclick="buildConnection();">开始建立链接</button>
<hr>
<input id="sendMsg" /> <button onclick="sendMessage();">消息发送</button>

</body>
</html>

测试结果如下：

????????点击建立连接

?

? ? ? ? 点击发送消息

?