使用Spring WebSocket实现消息推送

一、Spring WebSocket配置与实现

第一步： 添加Spring WebSocket的依赖jar包

（注：这里使用maven方式添加 手动添加的同学请自行下载相应jar包放到lib目录，本文使用的版本为4.3.5.RELEASE）

<!-- spring websocket-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-messaging</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-websocket</artifactId>
<version>${spring.version}</version>
</dependency>

第二步：建立一个类实现WebSocketConfigurer接口

（用于配置spring webSocket）

package org.zwc.ssm.websocket;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
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;

/**
* Created by zhangwenchao on 2017/11/20.
*/

@Configuration
@EnableWebMvc
@EnableWebSocket
public class SpringWebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {

public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
registry.addHandler(webSocketHandler(),"/websocket/socketServer.do")
.addInterceptors(new SpringWebSocketHandlerInterceptor());

registry.addHandler(webSocketHandler(), "/sockjs/socketServer.do")
.addInterceptors(new SpringWebSocketHandlerInterceptor()).withSockJS();
}

@Bean
public TextWebSocketHandler webSocketHandler(){

return new SpringWebSocketHandler();
}

}

 第三步：继承WebSocketHandler对象

(住：该对象提供了客户端连接,关闭,错误,发送等方法,重写这几个方法即可实现自定义业务逻辑)

package org.zwc.ssm.websocket;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
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;

/**
* Created by zhangwenchao on 2017/11/20.
*/
public class SpringWebSocketHandler extends TextWebSocketHandler {

private static Logger logger = LoggerFactory.getLogger(SpringWebSocketHandler.class);

private static final Map<String, WebSocketSession> users;  //Map来存储WebSocketSession，key用USER_ID 即在线用户列表

//用户标识
private static final String USER_ID = "WEBSOCKET_USERID";   //对应监听器从的key

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

public SpringWebSocketHandler() {}

/**
* 连接成功时候，会触发页面上onopen方法
*/
public void afterConnectionEstablished(WebSocketSession session) throws Exception {

System.out.println("成功建立websocket连接!");
String userId = (String) session.getAttributes().get(USER_ID);
users.put(userId,session);
System.out.println("当前线上用户数量:"+users.size());

//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("成功建立socket连接，你将收到的离线");
//session.sendMessage(returnMessage);
}

/**
* 关闭连接时触发
*/
public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {
logger.debug("关闭websocket连接");
String userId= (String) session.getAttributes().get(USER_ID);
System.out.println("用户"+userId+"已退出！");
users.remove(userId);
System.out.println("剩余在线用户"+users.size());
}

/**
* js调用websocket.send时候，会调用该方法
*/
@Override
protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {

super.handleTextMessage(session, message);

/**
* 收到消息，自定义处理机制，实现业务
*/
System.out.println("服务器收到消息："+message);

if(message.getPayload().startsWith("#anyone#")){ //单发某人

sendMessageToUser((String)session.getAttributes().get(USER_ID), new TextMessage("服务器单发：" +message.getPayload())) ;

}else if(message.getPayload().startsWith("#everyone#")){

sendMessageToUsers(new TextMessage("服务器群发：" +message.getPayload()));

}else{

}

}

public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
if(session.isOpen()){
session.close();
}
logger.debug("传输出现异常，关闭websocket连接... ");
String userId= (String) session.getAttributes().get(USER_ID);
users.remove(userId);
}

public boolean supportsPartialMessages() {

return false;
}

/**
* 给某个用户发送消息
*
* @param userId
* @param message
*/
public void sendMessageToUser(String userId, TextMessage message) {
for (String id : users.keySet()) {
if (id.equals(userId)) {
try {
if (users.get(id).isOpen()) {
users.get(id).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 (String userId : users.keySet()) {
try {
if (users.get(userId).isOpen()) {
users.get(userId).sendMessage(message);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}

}

第四步：继承HttpSessionHandshakeInterceptor对象

该对象作为页面连接websocket服务的拦截器

package org.zwc.ssm.websocket;

import java.util.Map;

import javax.servlet.http.HttpSession;

import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor;

/**
* Created by zhangwenchao on 2017/11/20.
* WebSocket拦截器----握手之前将登陆用户信息从session设置到WebSocketSession
*
*/
public class SpringWebSocketHandlerInterceptor 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("SESSION_USERNAME");  //一般直接保存user实体
if (userName!=null) {
attributes.put("WEBSOCKET_USERID",userName);
}

}
}
return super.beforeHandshake(request, response, wsHandler, attributes);

}

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

第5步 让SpringWebSocketConfig配置类随spring容器启动

spring文件中加入如下代码：

<!-- websocket相关扫描，主要扫描：WebSocketConfig  如果前面配置能扫描到此类则可以不加 -->
<context:component-scan base-package="org.zwc.ssm" />

上述完成之后，spring-websocket配置和实现就已经完成，接下来实现进行测试。

二、测试过程

1.定义一个控制器用来做登录连接和发送消息

package org.zwc.ssm.web;

import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.socket.TextMessage;
import org.zwc.ssm.websocket.SpringWebSocketHandler;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
* Created by zhangwenchao on 2017/11/20.
*/
@Controller
public class WebSocketController {

@Bean//这个注解会从Spring容器拿出Bean
public SpringWebSocketHandler infoHandler() {

return new SpringWebSocketHandler();
}

@RequestMapping("/websocket/loginPage")
public String loginPage(HttpServletRequest request, HttpServletResponse response) throws Exception {
return "/websocket/login";
}

@RequestMapping("/websocket/login")
public String login(HttpServletRequest request, HttpServletResponse response) throws Exception {
String username = request.getParameter("username");
System.out.println(username+"登录");
HttpSession session = request.getSession(false);
session.setAttribute("SESSION_USERNAME", username); //一般直接保存user实体
return "/websocket/send";
}

@RequestMapping("/websocket/send")
@ResponseBody
public String send(HttpServletRequest request) {
String username = request.getParameter("username");
infoHandler().sendMessageToUser(username, new TextMessage("你好，测试！！！！"));
return null;
}

@RequestMapping("/websocket/broad")
@ResponseBody
public  String broad() {
infoHandler().sendMessageToUsers(new TextMessage("发送一条小Broad"));
System.out.println("群发成功");
return "broad";
}

}

2.建立登录页面

<%@ page language="java" contentType="text/html; charset=UTF-8" 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}"/>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<title>测试spring websocket</title>
<!--
<link rel="stylesheet" href="/css/style.css"/>
<script type="text/javascript" src="/js/jquery/jquery.js"></script>
<script type="text/javascript">
</script>
-->
</head>
<body>

<form action="${ctx}/websocket/login">
登录名：<input type="text" name="username"/>
<input type="submit" value="登录聊天室"/>
</form>

</body>
</html>

3.建立发消息页面

<%@ page language="java" contentType="text/html; charset=UTF-8" 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}"/>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<title></title>
<!--
<link rel="stylesheet" href="/css/style.css"/>
-->
<script type="text/javascript" src="http://cdn.bootcss.com/jquery/3.1.0/jquery.min.js"></script>
<script type="text/javascript" src="http://cdn.bootcss.com/sockjs-client/1.1.1/sockjs.js"></script>
<script type="text/javascript">
var websocket = null;
if ('WebSocket' in window) {
websocket = new WebSocket("ws://localhost:8080/JavaWebTest/websocket/socketServer.do");
}
else if ('MozWebSocket' in window) {
websocket = new MozWebSocket("ws://localhost:8080/JavaWebTest/websocket/socketServer.do");
}
else {
websocket = new SockJS("http://localhost:8080/JavaWebTest/sockjs/socketServer.do");
}
websocket.onopen = onOpen;
websocket.onmessage = onMessage;
websocket.onerror = onError;
websocket.onclose = onClose;

function onOpen(openEvt) {
alert(openEvt.Data);
}

function onMessage(evt) {
alert(evt.data);
}
function onError() {}
function onClose() {}

function doSendUser() {
if (websocket.readyState == websocket.OPEN) {
var msg = document.getElementById("inputMsg").value;
websocket.send("#anyone#"+msg);//调用后台handleTextMessage方法
alert("发送成功!");
} else {
alert("连接失败!");
}
}

function doSendUsers() {
if (websocket.readyState == websocket.OPEN) {
var msg = document.getElementById("inputMsg").value;
websocket.send("#everyone#"+msg);//调用后台handleTextMessage方法
alert("发送成功!");
} else {
alert("连接失败!");
}
}

window.close=function()
{
websocket.onclose();
}
</script>

</head>
<body>

请输入：<textarea rows="5" cols="10" id="inputMsg" name="inputMsg"></textarea>
<button onclick="doSendUser();">发送</button>
<button onclick="doSendUsers();">群发</button>
</body>
</html>

4、测试结果

如下图所示：前台登录两个用户aaaa和bbbb，aaaa发送“哈哈，大家好”，群发给所用用户，用户aaaa和bbbb同时收到消息。



后台上线用户日志如图：