spring+websocket整合（springMVC+spring+MyBatis即SSM框架和websocket技术的整合）

大家好，又见面了，我是你们的朋友全栈君。

———————20170612更新——————————–

很多小伙伴反映原来的工程无法下载，这个锅得CSDN背，可能下载量达到一定程度就涉嫌违规了吧。现给出GitHub地址，增强简化配置版的demo，可能跟下文讲的不完全匹配，但原理是一样的，只不过省去了配置而改用注解。

Git JavaWebSocket地址，尽量star一下哦，不定期增强更新功能。

——————-我是阔爱的分割线——————————–

spring4.0以后加入了对websocket技术的支持，撸主目前的项目用的是SSM（springMVC+spring+MyBatis）框

架，所以肯定要首选spring自带的websocket了，好，现在问题来了，撸主在网上各种狂搜猛找，拼凑了几个自称是

spring websocket的东东，下来一看，废物，其中包括从github上down下来的。举个例子，在搭建过程中有个问题，

撸主上谷歌搜索，总共搜出来三页结果共30条左右，前15条是纯英文的后15条是韩语和日语，而这30条结果都不能

解决撸主的问题，无奈，只好上官网看全英帮助，在撸主惊人的毅力和不懈奋斗下，纠结了两天的spring+websocket

整合今天算是彻底搭建成功，摸索透彻了。

websocket是目前唯一真正实现全双工通信的服务器向客户端推的互联网技术，与长连接和轮询技术相比，

websocket的优越性不言自明，长连接的连接资源（线程资源）随着连接数量的增多，必会耗尽，客户端轮询会给服

务器造成很大的压力，而websocket是在物理层非网络层建立一条客户端至服务器的长连接，以此来保证服务器向客

户端的即时推送，既不耗费线程资源，又不会不断向服务器轮询请求。

下面言归正传，讲一讲撸主在SSM（springMVC+spring+MyBatis）框架中集成websocket技术的曲折蛋疼直至成功喜悦之路。

1 在maven的pom.xml中加入websocket所依赖的jar包，什么，你不知道maven，快去度之或者查看撸主关于maven的博文恶补一下，spring-websocket所依赖的jar包有以下几个：

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.1.0</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.3.0</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.3.0</version>
</dependency>
<dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-websocket</artifactId>
   <version>4.0.1.RELEASE</version>
</dependency>
<dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-messaging</artifactId>
   <version>4.0.1.RELEASE</version>
</dependency>

2 更新web.xml中namespace.xsd的版本，

<beans xmlns="http://www.springframework.org/schema/beans"
	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	   xmlns:websocket="http://www.springframework.org/schema/websocket"
	   xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/websocket http://www.springframework.org/schema/websocket/spring-websocket.xsd">

3 更新spring框架的jar包至4.0以上（spring-core, spring-context, spring-web and spring-webmvc）

<dependency>
<span style="white-space:pre">	</span><groupId>org.springframework</groupId>
	<artifactId>spring-core</artifactId>
	<version>${spring.version}</version>
</dependency>
<dependency>
	<groupId>org.springframework</groupId>
	<artifactId>spring-web</artifactId>
	<version>${spring.version}</version>
</dependency>
<dependency>
	<groupId>org.springframework</groupId>
	<artifactId>spring-webmvc</artifactId>
	<version>${spring.version}</version>
</dependency>
<dependency>
	<groupId>org.springframework</groupId>
	<artifactId>spring-context-support</artifactId>
	<version>${spring.version}</version>
</dependency>

4 4.1创建websocket处理类

package com.up.websocket.handler;

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

public class WebsocketEndPoint extends TextWebSocketHandler {

	@Override
	protected void handleTextMessage(WebSocketSession session,
			TextMessage message) throws Exception {
		super.handleTextMessage(session, message);
		TextMessage returnMessage = new TextMessage(message.getPayload()+" received at server");
		session.sendMessage(returnMessage);
	}
}

4.2创建握手（handshake）接口

package com.up.websocket;

import java.util.Map;

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;

public class HandshakeInterceptor extends HttpSessionHandshakeInterceptor{

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

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

}

5 处理类和握手协议的spring配置(applicationContext.xml文件）

<bean id="websocket" class="com.up.websocket.handler.WebsocketEndPoint"/>

<websocket:handlers>
    <websocket:mapping path="/websocket" handler="websocket"/>
    <websocket:handshake-interceptors>
    <bean class="com.up.websocket.HandshakeInterceptor"/>
    </websocket:handshake-interceptors>
</websocket:handlers>

6 客户端页面

<!DOCTYPE html>
<html>
<head>
    <title>WebSocket/SockJS Echo Sample (Adapted from Tomcat's echo sample)</title>
    <style type="text/css">
        #connect-container {
            float: left;
            width: 400px
        }

        #connect-container div {
            padding: 5px;
        }

        #console-container {
            float: left;
            margin-left: 15px;
            width: 400px;
        }

        #console {
            border: 1px solid #CCCCCC;
            border-right-color: #999999;
            border-bottom-color: #999999;
            height: 170px;
            overflow-y: scroll;
            padding: 5px;
            width: 100%;
        }

        #console p {
            padding: 0;
            margin: 0;
        }
    </style>

    <script src="http://cdn.sockjs.org/sockjs-0.3.min.js"></script>

    <script type="text/javascript">
        var ws = null;
        var url = null;
        var transports = [];

        function setConnected(connected) {
            document.getElementById('connect').disabled = connected;
            document.getElementById('disconnect').disabled = !connected;
            document.getElementById('echo').disabled = !connected;
        }

        function connect() {
        	alert("url:"+url);
            if (!url) {
                alert('Select whether to use W3C WebSocket or SockJS');
                return;
            }

            ws = (url.indexOf('sockjs') != -1) ? 
                new SockJS(url, undefined, {protocols_whitelist: transports}) : new WebSocket(url);

            ws.onopen = function () {
                setConnected(true);
                log('Info: connection opened.');
            };
            ws.onmessage = function (event) {
                log('Received: ' + event.data);
            };
            ws.onclose = function (event) {
                setConnected(false);
                log('Info: connection closed.');
                log(event);
            };
        }

        function disconnect() {
            if (ws != null) {
                ws.close();
                ws = null;
            }
            setConnected(false);
        }

        function echo() {
            if (ws != null) {
                var message = document.getElementById('message').value;
                log('Sent: ' + message);
                ws.send(message);
            } else {
                alert('connection not established, please connect.');
            }
        }

        function updateUrl(urlPath) {
            if (urlPath.indexOf('sockjs') != -1) {
                url = urlPath;
                document.getElementById('sockJsTransportSelect').style.visibility = 'visible';
            }
            else {
              if (window.location.protocol == 'http:') {
                  url = 'ws://' + window.location.host + urlPath;
              } else {
                  url = 'wss://' + window.location.host + urlPath;
              }
              document.getElementById('sockJsTransportSelect').style.visibility = 'hidden';
            }
        }

        function updateTransport(transport) {
        	alert(transport);
          transports = (transport == 'all') ?  [] : [transport];
        }
        
        function log(message) {
            var console = document.getElementById('console');
            var p = document.createElement('p');
            p.style.wordWrap = 'break-word';
            p.appendChild(document.createTextNode(message));
            console.appendChild(p);
            while (console.childNodes.length > 25) {
                console.removeChild(console.firstChild);
            }
            console.scrollTop = console.scrollHeight;
        }
    </script>
</head>
<body>
<noscript><h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websockets 
    rely on Javascript being enabled. Please enable
    Javascript and reload this page!</h2></noscript>
<div>
    <div id="connect-container">
        <input id="radio1" type="radio" name="group1" οnclick="updateUrl(''/spring-websocket-uptest/websocket');">
            <label for="radio1">W3C WebSocket</label>
        <br>
        <input id="radio2" type="radio" name="group1" οnclick="updateUrl('/spring-websocket-uptest/websocket');">
            <label for="radio2">SockJS</label>
        <div id="sockJsTransportSelect" style="visibility:hidden;">
            <span>SockJS transport:</span>
            <select οnchange="updateTransport(this.value)">
              <option value="all">all</option>
              <option value="websocket">websocket</option>
              <option value="xhr-polling">xhr-polling</option>
              <option value="jsonp-polling">jsonp-polling</option>
              <option value="xhr-streaming">xhr-streaming</option>
              <option value="iframe-eventsource">iframe-eventsource</option>
              <option value="iframe-htmlfile">iframe-htmlfile</option>
            </select>
        </div>
        <div>
            <button id="connect" οnclick="connect();">Connect</button>
            <button id="disconnect" disabled="disabled" οnclick="disconnect();">Disconnect</button>
        </div>
        <div>
            <textarea id="message" style="width: 350px">Here is a message!</textarea>
        </div>
        <div>
            <button id="echo" οnclick="echo();" disabled="disabled">Echo message</button>
        </div>
    </div>
    <div id="console-container">
        <div id="console"></div>
    </div>
</div>
</body>
</html>