Spring和WebSocket整合详解

梦里梦外; 2022-03-20 05:44 755阅读 0赞

## Spring和WebSocket整合详解 ##

**本篇编写日期较早，代码冗余较多，新博文：[Spring和WebSocket整合并建立简单的Web聊天室][Spring_WebSocket_Web]**

### 官方主页 ###

[Spring WebSocket][]

### 概述 ###

WebSocket 是一种网络通信协议。RFC6455 定义了它的通信标准。  
WebSocket 是 HTML5 开始提供的一种在单个 TCP 连接上进行全双工通讯的协议。

HTTP 协议是一种无状态的、无连接的、单向的应用层协议。它采用了请求/响应模型。通信请求只能由客户端发起，服务端对请求做出应答处理。  
这种通信模型有一个弊端：HTTP 协议无法实现服务器主动向客户端发起消息。  
这种单向请求的特点，注定了如果服务器有连续的状态变化，客户端要获知就非常麻烦。大多数 Web 应用程序将通过频繁的异步JavaScript和XML（AJAX）请求实现长轮询。轮询的效率低，非常浪费资源（因为必须不停连接，或者 HTTP 连接始终打开）。

因此，工程师们一直在思考，有没有更好的方法。WebSocket 就是这样发明的。WebSocket 连接允许客户端和服务器之间进行全双工通信，以便任一方都可以通过建立的连接将数据推送到另一端。WebSocket 只需要建立一次连接，就可以一直保持连接状态。这相比于轮询方式的不停建立连接显然效率要大大提高。

Web浏览器和服务器都必须实现 WebSockets 协议来建立和维护连接。由于 WebSockets 连接长期存在，与典型的HTTP连接不同，对服务器有重要的影响。

基于多线程或多进程的服务器无法适用于 WebSockets，因为它旨在打开连接，尽可能快地处理请求，然后关闭连接。任何实际的 WebSockets 服务器端实现都需要一个异步服务器。

这里，我们基于Spring整合原生的WebSocket，实现简单的IM聊天功能。

Git地址：  
[Gitee][]

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[品茗IT-同步发布][IT-]

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### 开始搭建 ###

#### 依赖Jar包 ####

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

#### spring-websocket.xml ####

该xml文件仅作为配置文件的引入使用。

<?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:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd ">
    
    	<bean id="annotationPropertyConfigurerWebSocket" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    		<property name="order" value="1" />
    		<property name="ignoreUnresolvablePlaceholders" value="true" />
    		<property name="locations">
    			<list>
    				<value>classpath:websocket.properties</value>
    			</list>
    		</property>
    	</bean>
    	
    </beans>

websocket.properties保存一些自定义配置，这里没用上，就不贴出来了。

#### WebSocket配置监听 ####

Spring整合WebSocket需要配置websocket的监听url。

SpringWebSocketConfig：

package com.cff.springwork.websocket.config;
    
    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;
    
    import com.cff.springwork.websocket.handler.WebsocketHandler;
    
    
    @Configuration
    @EnableWebMvc
    @EnableWebSocket
    public class SpringWebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer { 
        public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) { 
            registry.addHandler(webSocketHandler(),"/websocket").addInterceptors(new WebSocketInterceptor());
            registry.addHandler(webSocketHandler(), "/sockjs").addInterceptors(new WebSocketInterceptor()).withSockJS();
        }
     
        @Bean
        public TextWebSocketHandler webSocketHandler(){ 
            return new WebsocketHandler();
        }
    
    }

#### WebSocket的session拦截处理 ####

WebSocketInterceptor对WebSocket的连接进行过滤，可以对连接前和连接后自定义处理。

WebSocketInterceptor：

package com.cff.springwork.websocket.config;
    
    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.stereotype.Component;
    import org.springframework.web.socket.WebSocketHandler;  
    import org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor;  
    
    @Component
    public class WebSocketInterceptor 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("userId");
                    if (userName==null) { 
                        userName="default";
                    }
                    attributes.put("userId",userName);
                }
            }
            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);  
        }  
      
    }

#### 消息处理（处理逻辑配合下面的聊天室） ####

WebsocketHandler负责处理消息发送接收的逻辑：

package com.cff.springwork.websocket.handler;
    
    import java.io.IOException;
    import java.util.List;
    
    import org.apache.commons.lang.StringUtils;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.web.socket.BinaryMessage;
    import org.springframework.web.socket.CloseStatus;
    import org.springframework.web.socket.TextMessage;
    import org.springframework.web.socket.WebSocketMessage;
    import org.springframework.web.socket.WebSocketSession;  
    import org.springframework.web.socket.handler.TextWebSocketHandler;
    
    import com.cff.springwork.websocket.memory.WebSocketUser;
      
    public class WebsocketHandler extends TextWebSocketHandler {   
    	protected Logger logger = LoggerFactory.getLogger(getClass());
    	public static WebSocketUser users = new WebSocketUser();
    	public WebsocketHandler(){ 
    		
    	}
    	
    	
        @Override  
        protected void handleTextMessage(WebSocketSession session,  
                TextMessage message) throws Exception {   
        	logger.info("websocketmsg:{}",message.toString()); 
            super.handleTextMessage(session, message);  
            String msg = message.getPayload();
            logger.info("websocketmsg1:{}",msg); 
            if(StringUtils.isNotEmpty(msg)){ 
            	String param[] = msg.split("\\|");
            	String userName = (String)session.getAttributes().get("userName");
            	sendMessageToUser(param[1], new TextMessage(param[0]+"|"+userName+"|"+param[2]));
            }
    // TextMessage returnMessage = new TextMessage(message.getPayload()+" received at server"); 
    // session.sendMessage(returnMessage); 
        }
    
    	@Override
    	public void afterConnectionEstablished(WebSocketSession session) throws Exception { 
    		String userName = (String)session.getAttributes().get("userName");
    		String msgType="0000";
    		if(userName == null || "".equals(userName)){ 
    			long id = users.getWebsocketId();
    			logger.info("random UserId:{}",id); 
    			users.putUserNameAndWebSocketSession(id+"", session);
    			
    			session.sendMessage(new TextMessage(msgType+"|"+ id));
    		}else{ 
    			logger.info("UserName:{}",userName); 
    			//users.putNickNameAndWebSocketSession(userInfo.getNickName(), session);
    			users.putUserNameAndWebSocketSession(userName, session);
    			session.sendMessage(new TextMessage(msgType+"|"+userName));
    		}
    		
    
    		List<TextMessage> message = WebsocketHandler.getOfflineMsg(userName);
    	    if( message !=null && message.size()!=0){ 
    	    	for(int i = 0; i < message.size(); i++){ 
    	    		WebsocketHandler.sendMessageToUser(userName, message.get(i));
    	    	}
    	    }
    	}
    
    	@Override
    	public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception { 
    // 
    // super.afterConnectionClosed(session, status);
    		users.removeWebSocketSession(session);
    		
    	}
        
    	/** * 给某个用户发送消息 * * @param userName * @param message */
        public static void sendMessageToUser(String userName, TextMessage message) { 
        	List<WebSocketSession> webUsers = users.getWebSocketSessionWithUserName(userName);
        	System.out.println(webUsers);
        	System.out.println(userName);
        	if (webUsers == null || webUsers.size() == 0){ 
        		users.putOfflineMsg(userName, message);
        		return;
        	}
        	for(int i =0; i < webUsers.size(); i++){ 
    	    	WebSocketSession user = webUsers.get(i);
    	    	System.out.println(user);
    	    	
    	        try { 
    	            if (user.isOpen()) { 
    	            	user.sendMessage(message);
    	            }
    	        } catch (IOException e) { 
    	            e.printStackTrace();
    	        } 
        	}
        }
        
        
        /** * 给某个用户发送消息 * * @param userName * @param message */
        public static void sendBinaryMessageToUser(String userName, BinaryMessage message) { 
        	List<WebSocketSession> webUsers = users.getWebSocketSessionWithUserName(userName);
        	System.out.println(webUsers);
        	System.out.println(userName);
        	if (webUsers == null || webUsers.size() == 0){ 
        		//users.putOfflineMsg(userName, message);
        		return;
        	}
        	for(int i =0; i < webUsers.size(); i++){ 
    	    	WebSocketSession user = webUsers.get(i);
    	    	System.out.println(user);
    	    	
    	        try { 
    	            if (user.isOpen()) { 
    	            	user.sendMessage(message);
    	            }
    	        } catch (IOException e) { 
    	            e.printStackTrace();
    	        } 
        	}
        }
        
        public static List<TextMessage> getOfflineMsg(String userName){ 
        	return users.getOfflineMsgWithUserName(userName);
        }
    }

WebSocketUser是使用内存来存储用户：

package com.cff.springwork.websocket.memory;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    import java.util.concurrent.ConcurrentHashMap;
    
    import org.springframework.web.socket.TextMessage;
    import org.springframework.web.socket.WebSocketSession;
    
    public class WebSocketUser { 
    	private static Map<String,List<WebSocketSession>> userNameWebsession = null;
    	private static Map<WebSocketSession,String> webSessionUserName = null;
    	private static Map<String,List<TextMessage>> userNameWithOfflineMsg = null;
    	private static long websocketId = 100000000L;
    	
    	public WebSocketUser(){ 
    		userNameWebsession = new ConcurrentHashMap<String,List<WebSocketSession>>();
    		webSessionUserName = new ConcurrentHashMap<WebSocketSession,String>();
    		userNameWithOfflineMsg = new ConcurrentHashMap<String,List<TextMessage>>();
    	}
    	
    	public Map<String,List<WebSocketSession>> getUserNameWebsession(){ 
    		return userNameWebsession;
    	}
    	
    	public Map<WebSocketSession,String> getWebSessionUserName(){ 
    		return webSessionUserName;
    	}
    	
    	public String getUserNameWithWebSocketSession(WebSocketSession webSocketSession){ 
    		return webSessionUserName.get(webSocketSession); 
    	}
    
    	public static Map<String, List<TextMessage>> getUserNameWithOfflineMsg() { 
    		return userNameWithOfflineMsg;
    	}
    
    	public static void setUserNameWithOfflineMsg(Map<String, List<TextMessage>> userNameWithOfflineMsg) { 
    		WebSocketUser.userNameWithOfflineMsg = userNameWithOfflineMsg;
    	}
    
    	public static void setUserNameWebsession(Map<String, List<WebSocketSession>> userNameWebsession) { 
    		WebSocketUser.userNameWebsession = userNameWebsession;
    	}
    
    	public static void setWebSessionUserName(Map<WebSocketSession, String> webSessionUserName) { 
    		WebSocketUser.webSessionUserName = webSessionUserName;
    	}
    
    	/** * 根据昵称拿WebSocketSession * @param nickName * @return */
    	public List<WebSocketSession> getWebSocketSessionWithUserName(String userName){ 
    		return userNameWebsession.get(userName);
    	}
    	
    	/** * 移除失效的WebSocketSession * @param webSocketSession */
    	public synchronized void removeWebSocketSession(WebSocketSession webSocketSession){ 
    		if (webSocketSession == null) return;
    		String nickName = webSessionUserName.get(webSocketSession);
    		webSessionUserName.remove(webSocketSession);
    		List<WebSocketSession> webSessoin = userNameWebsession.get(nickName);
    		if (webSessoin == null) return;
    		webSessoin.remove(webSocketSession);
    	}
    	
    	/** * 存放离线消息 * @param nickName * @param msg */
    	public synchronized void putOfflineMsg(String userName, TextMessage msg){ 
    		if (userNameWithOfflineMsg.get(userName) == null){ 
    			List<TextMessage> msgList = new ArrayList<TextMessage>();
    			msgList.add(msg);
    			userNameWithOfflineMsg.put(userName, msgList);
    		}else{ 
    			List<TextMessage> msgList = userNameWithOfflineMsg.get(userName);
    			msgList.add(msg);
    		}
    	}
    	
    	/** * 根据昵称拿离线消息 * @param nickName * @return */
    	public List<TextMessage> getOfflineMsgWithUserName(String userName){ 
    		return userNameWithOfflineMsg.get(userName);
    	}
    	
    	/** * 存放昵称和WebSocketSession * @param nickName * @param webSocketSession */
    	public synchronized void putUserNameAndWebSocketSession(String userName, WebSocketSession webSocketSession){ 
    		webSessionUserName.put(webSocketSession, userName);
    		if (userNameWebsession.get(userName) == null){ 
    			List<WebSocketSession> webSessoin = new ArrayList<WebSocketSession>();
    			webSessoin.add(webSocketSession);
    			userNameWebsession.put(userName, webSessoin);
    		}else{ 
    			List<WebSocketSession> webSessoin = userNameWebsession.get(userName);
    			webSessoin.add(webSocketSession);
    		}
    	}
    	
    	/** * 移除失效的WebSocketSession * @param webSocketSession */
    	public synchronized long getWebsocketId(){ 
    		websocketId += 1;
    		return websocketId;
    	}
    	
    	public static void main(String srga[]){ 
    		String test = "123456";
    		
    		Boolean flag = true;
    		if(test == "012345678".substring(1, 7)){ 
    			flag = false;
    		}
    		System.out.println(flag);
    	}
    }

#### 聊天室 ####

为了实现我们的简单聊天功能，我们需要前端进行配合。

websocketchat.jsp实现了简单的聊天室，支持文字、表情、文件等：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    	pageEncoding="UTF-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <%@ include file="/common/head.jsp"%>
    
    <script type="text/javascript" src="${ctx}/js/jquery/jquery-3.2.1.min.js" ></script>
    <script src="${ctx}/js/websocket/websocket.js"></script>
    <script src="${ctx}/js/jquery/ajaxfileupload.js"></script>
    <script src="${ctx}/js/jquery/jquery-browser.js"></script>
    <script src="${ctx}/js/jquery/jquery.qqFace.js"></script>
    <head>
    <title>聊天室</title>
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <meta http-equiv="content-script-type" content="text/javascript">
    <meta http-equiv="content-style-type" content="text/css">
    <style rel="stylesheet" type="text/css" media="all" /> body { text-align:left; margin:0; font:normal 12px Verdana, Arial; background:#FFEEFF } form { margin:0; font:normal 12px Verdana, Arial; } table,input { font:normal 12px Verdana, Arial; } a:link,a:visited{ text-decoration:none; color:#333333; } a:hover{ text-decoration:none; color:#FF6600 } #main { width:400px; position:absolute; left:600px; top:100px; background:#EFEFFF; text-align:left; filter:Alpha(opacity=90) } #ChatHead { text-align:right; padding:3px; border:1px solid #003399; background:#DCDCFF; font-size:20px; color:#3366FF; cursor:move; } #ChatHead a:link,#ChatHead a:visited, { font-size:14px; font-weight:bold; padding:0 3px } #ChatBody { border:1px solid #003399; border-top:none; padding:2px; } #ChatContent { height:200px; padding:6px; overflow-y:scroll; word-break: break-all }#ChatBtn { border-top:1px solid #003399; padding:2px } </style>
    <script language="javascript" type="text/javascript"> var ws = null; var msgUser=null; var muserId = null; var nickName =""; var contextPath = '${ctx}'; var imgName = null; var fileImgSize = 0; window.onbeforeunload = function() { disconnect(ws); } function ChatSetUser(user,userId) { if(muserId != null && muserId != userId){ $("#ChatContent").html(""); } msgUser = user; muserId = userId; imgName = msgUser; //alert("owerId:" + nickName + "-----msgUser:" + msgUser); //alert("userId:" + nickName + "-----userId:" + muserId); if (msgUser == nickName) { return; } if (msgUser == "") { return; } ChatNew(); } function gs(d) { var t = document.getElementById(d); if (t) { return t.style; } else { return null; } } function gs2(d, a) { if (d.currentStyle) { var curVal = d.currentStyle[a] } else { var curVal = document.defaultView .getComputedStyle(d, null)[a] } return curVal; } function ChatHidden() { gs("ChatBody").display = "none"; } function ChatShow() { gs("ChatBody").display = ""; } function ChatClose() { gs("main").display = "none"; //disconnect(ws); } function ChatNew() { gs("main").display = ""; $("#ChatUsers").html(msgUser); $('.emotion').qqFace({ id : 'facebox', assign:'saytext', path: contextPath+'/img/arclist/' //表情存放的路径 }); } function ChatClear(obj) { $("#ChatContent").html(""); } function ChatRead() { document.getElementById(msgUser).setAttribute('src', contextPath+'/img/users.png'); } function ChatSend(obj) { var o = obj.ChatValue; var msg = replace_em(o.value); if (o.value.length > 0) { $("#ChatContent").append( "<p align=\"right\"><strong>" + nickName + "(我) ：</strong>" + msg + "</p>"); var number = $("#ChatContent").scrollTop(); number += 16; $("#ChatContent").scrollTop(number); if(ws!=null){ ws.send("0001" + "|" + muserId + "|" + encodeURI(o.value)); } o.value = ''; } var img = obj.ChatFile; if (img.value.length > 0){ $("#ChatContent").append( "<p align=\"right\"><strong>" + nickName + "(我) ：</strong>" + img.value + "</p><br/>"); imgName = nickName+'（我）'; fileImgSize = img.files.length; //alert(fileImgSize); $.ajaxFileUpload({ //处理文件上传操作的服务器端地址(可以传参数,已亲测可用) url:'${ctx}/webSocket/fileUpload?userId='+muserId, secureuri:true, //是否启用安全提交,默认为false fileElementId:'ChatFile', //文件选择框的id属性 dataType:'text', //服务器返回的格式,可以是json或xml等 success:function(data, status){ //服务器响应成功时的处理函数 //$("#ChatContent").append("<p align=\"right\">" + data + "</p><br/>"); }, error:function(data, status, e){ //服务器响应失败时的处理函数 $("#ChatContent").append('<p align=\"right\">图片上传失败，请重试！！</p><br/>'); imgName = msgUser; } }); } } if (document.getElementById) { (function() { if (window.opera) { document.write("<input type='hidden' id='Q' value=' '>"); } var n = 500; var dragok = false; var y, x, d, dy, dx; function move(e) { if (!e) e = window.event; if (dragok) { d.style.left = dx + e.clientX - x + "px"; d.style.top = dy + e.clientY - y + "px"; return false; } } function down(e) { if (!e) e = window.event; var temp = (typeof e.target != "undefined") ? e.target : e.srcElement; if (temp.tagName != "HTML" | "BODY" && temp.className != "dragclass") { temp = (typeof temp.parentNode != "undefined") ? temp.parentNode : temp.parentElement; } if ('TR' == temp.tagName) { temp = (typeof temp.parentNode != "undefined") ? temp.parentNode : temp.parentElement; temp = (typeof temp.parentNode != "undefined") ? temp.parentNode : temp.parentElement; temp = (typeof temp.parentNode != "undefined") ? temp.parentNode : temp.parentElement; } if (temp.className == "dragclass") { if (window.opera) { document.getElementById("Q").focus(); } dragok = true; temp.style.zIndex = n++; d = temp; dx = parseInt(gs2(temp, "left")) | 0; dy = parseInt(gs2(temp, "top")) | 0; x = e.clientX; y = e.clientY; document.onmousemove = move; return false; } } function up() { dragok = false; document.onmousemove = null; } document.onmousedown = down; document.onmouseup = up; })(); } function toIndex(){ window.location.href= contextPath + "/index.jsp"; } $(function() { if (ws == null) { var url = getUrl(); //alert("url:"+url); if (!url) { return; } ws = new WebSocket(url); connect(ws); } ChatClose(); // ChatSetUser("human","16888888888"); }) </script>
    </head>
    
    <body>
    	<div>
    		<div style="display: inline;">
    			<img style="width: 5%;margin-left: 100px;" alt="" src="${ctx}/img/logo.png" onclick="toIndex()"/>
    		</div>
    		<div style="display: inline; float: right">
    			<img style="width: 220px;display:block;margin-top: 15px;margin-right: 200px;" alt="" src="${ctx}/img/logoright.png"/>
    		</div>
    	</div>
    	<div id="main" class="dragclass" onclick="ChatRead()" style="left: 400px; top: 200px;">
    		<div id="ChatUsers" style="width:100px; padding:3px; font-size:15px;float:left; display:inline"></div>
    		<div id="ChatHead">
    			<a href="#" onclick="ChatHidden();">-</a> <a href="#" onclick="ChatShow();">+</a> <a href="#" onclick="ChatClose();">x</a>
    		</div>
    		<div id="ChatBody">
    			<div id="ChatContent"></div>
    			<div id="ChatBtn">
    				<form action="" name="chat" method="post">
    					<textarea name="ChatValue" id="saytext" rows="3" style="width: 350px"></textarea>
    					<input name="Submit" type="button" value="发送" onclick="ChatSend(this.form);" />
    					<input name="ClearMsg" type="button" value="清空记录" onclick="ChatClear(this.form);" />
    					<input type="button" class="emotion" value="表情">
    					<input id="ChatFile" type="file" name="myfiles" multiple>   
    				</form>
    			</div>
    		</div>
    	</div>
    	<div align="left" style="margin-top: 50px;margin-left: 20px;">
    		<p id=RandomContent>欢迎您，15607110725</p>
    		<p id=content></p>
    	</div>
    	
    </body>
    </html>

这个jsp需要websocket.js配合：

以上已经支持表情和文字发送，要支持图片，需要我们自定义发送文件功能WebSocketController：

package com.cff.springwork.websocket.endpoint;
    
    import java.io.ByteArrayInputStream;
    import java.io.ByteArrayOutputStream;
    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.PrintWriter;
    import java.io.UnsupportedEncodingException;
    import java.net.URLDecoder;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.stereotype.Controller;
    import org.springframework.util.StringUtils;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.multipart.MultipartFile;
    import org.springframework.web.socket.BinaryMessage;
    
    import com.cff.springwork.websocket.handler.WebsocketHandler;
    
    @Controller("webSocketController")
    @RequestMapping("/webSocket")
    public class WebSocketController { 
    	protected Logger logger = LoggerFactory.getLogger(getClass());
    	
    	@RequestMapping(value="/fileUpload")
    	public void fileUpload(@RequestParam("userId") String userId, @RequestParam MultipartFile[] myfiles, HttpServletRequest request, HttpServletResponse response) throws IOException{ 
    		//可以在上传文件的同时接收其它参数
    		System.out.println("收到发往用户[" + userId + "]的文件上传请求");
    		
    		//如果用的是Tomcat服务器，则文件会上传到\\%TOMCAT_HOME%\\webapps\\YourWebProject\\upload\\文件夹中
    		//这里实现文件上传操作用的是commons.io.FileUtils类,它会自动判断/upload是否存在,不存在会自动创建
    		String realPath = request.getSession().getServletContext().getRealPath("/upload");
    		System.out.println("路径[" + realPath + "]的文件上传请求");
    		System.out.println("文件数量："+myfiles.length);
    		realPath = "D:/doc/";
    		//设置响应给前台内容的数据格式
    		response.setContentType("text/plain; charset=UTF-8");
    		//上传文件的原名(即上传前的文件名字)
    		String originalFilename = null;
    		//如果只是上传一个文件,则只需要MultipartFile类型接收文件即可,而且无需显式指定@RequestParam注解
    		//如果想上传多个文件,那么这里就要用MultipartFile[]类型来接收文件,并且要指定@RequestParam注解
    		//上传多个文件时,前台表单中的所有<input type="file"/>的name都应该是myfiles,否则参数里的myfiles无法获取到所有上传的文件
    		for(MultipartFile myfile : myfiles){ 
    			if(myfile.isEmpty()){ 
    				response.setCharacterEncoding("UTF-8");
    				response.getWriter().write("102");
    				return;
    			}else{ 
    				originalFilename = myfile.getOriginalFilename();
    				System.out.println("文件原名: " + originalFilename);
    				System.out.println("文件名称: " + myfile.getName());
    				System.out.println("文件长度: " + myfile.getSize());
    				System.out.println("文件类型: " + myfile.getContentType());
    				System.out.println("========================================");
    				try { 
    					//这里不必处理IO流关闭的问题,因为FileUtils.copyInputStreamToFile()方法内部会自动把用到的IO流关掉
    					//此处也可以使用Spring提供的MultipartFile.transferTo(File dest)方法实现文件的上传
    					//FileUtils.copyInputStreamToFile(myfile.getInputStream(), new File(realPath, originalFilename));
    					
    					ByteArrayOutputStream swapStream = new ByteArrayOutputStream(); 
    					byte[] buff = new byte[100]; //buff用于存放循环读取的临时数据 
    					int rc = 0; 
    					InputStream is = myfile.getInputStream();
    					while ((rc = is.read(buff, 0, 100)) > 0) {  
    					swapStream.write(buff, 0, rc); 
    					} 
    					byte[] in_b = swapStream.toByteArray(); //in_b为转换之后的结果
    					System.out.println("正在发送文件: ");
    
    					WebsocketHandler.sendBinaryMessageToUser(userId,new BinaryMessage(in_b));
    				} catch (IOException e) { 
    					System.out.println("文件[" + originalFilename + "]上传失败,堆栈轨迹如下");
    					e.printStackTrace();
    					response.setCharacterEncoding("UTF-8");
    					response.getWriter().write("101");
    					return ;
    				}
    			}
    		}
    		response.setCharacterEncoding("UTF-8");
    		response.getWriter().write("200");
    		return;
    	}
    	
    }

详细完整代码，可以在[Spring组件化构建][Spring]中选择查看，并下载。

### 快速构建项目 ###

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[Spring_WebSocket_Web]: https://blog.csdn.net/feiyangtianyao/article/details/100137436
[Spring WebSocket]: https://docs.spring.io/spring-session/docs/current/reference/html5/guides/boot-websocket.html
[Gitee]: https://gitee.com/ffch/springwork/tree/master/springwork-websocket
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