[WebSocket入门]搭建WebSocket多人在线聊天室笔记（SpringBoot+WebSocket）

 

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前言

使用websocket创建多人在线聊天室，本文参考了老外的一篇文章：https://www.callicoder.com/spring-boot-websocket-chat-example/

一、WebSocket是什么？

WebSocket是在单个TCP连接上进行全双工通信的协议，可以在服务器和客户端之间建立双向通信通道。

WebSocket 首先与服务器建立常规 HTTP 连接，然后通过发送Upgrade标头将其升级为双向 WebSocket 连接。

WebSocket使得客户端和服务器之间的数据交换变得更加简单，允许服务端主动向客户端推送数据。在WebSocket API中，浏览器和服务器只需要完成一次握手，两者之间就直接可以创建持久性的连接，并进行双向数据传输。

 

二、多人在线聊天室程序创建步骤

1、修改pom.xml文件

 在springboot2程序中，在pom.xml添加websocket依赖：

        
            org.springframework.boot
            spring-boot-starter-websocket
        

2、WebSocket 配置

新建config文件夹，在文件夹下创建WebsocketConfig.java文件：

import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.simp.config.MessageBrokerRegistry;
import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
import org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurer;

@Configuration
@EnableWebSocketMessageBroker
public class WebsocketConfig implements WebSocketMessageBrokerConfigurer {
    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/ws").withSockJS();
    }

    @Override
    public void configureMessageBroker(MessageBrokerRegistry registry) {
        registry.setApplicationDestinationPrefixes("/app");
        registry.enableSimpleBroker("/topic");
    }
}

1、@EnableWebSocketMessageBroker：注解开启使用STOMP协议来传输基于代理(message broker)的消息,这时控制器支持使用@MessageMapping,就像使用@RequestMapping一样

2、通过WebSocketMessageBrokerConfigurer继承WebSocket消息代理的类，配置相关信息；在该类里面重载了两个方法：registerStompEndpoints()与configureMessageBroker()。

• 重载registerStompEndpoints()方法：

addEndpoint方法：添加STOMP协议的端点。这个HTTP URL是供WebSocket或SockJS客户端访问的地址;

withSockJS：指定端点使用SockJS协议

• 重载configureMessageBroker()方法：在该方法里设置简单消息代理，并配置消息的发送的地址符合配置的前缀的消息才发送到这个broker

registry.setApplicationDestinationPrefixes("/app")：全局(客户端)使用的消息前缀

3、创建 Message 实体

新建entity文件夹，在文件夹下创建实体类Message：

package com.chen.my_chat.entity;


public class Message {
    public enum MessageType {
        CHAT,
        JOIN,
        LEAVE
    }
    private MessageType type;
    private String content;
    private String sender;

    public MessageType getType() {
        return type;
    }

    public void setType(MessageType type) {
        this.type = type;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public String getSender() {
        return sender;
    }

    public void setSender(String sender) {
        this.sender = sender;
    }
}

在实体类Message中，type（枚举类型）表示消息类型，content表示消息内容，sender表示发送人。MessageType中的CHAT表示消息、JOIN表示加入、LEAVE表示离开。

4、创建Controller来接收和发送消息

创建MessageController.java文件，将负责从一个客户端接收消息，然后将其广播给其他客户端。

package com.chen.my_chat.controller;

import com.chen.my_chat.entity.Message;
import org.springframework.messaging.handler.annotation.MessageMapping;
import org.springframework.messaging.handler.annotation.Payload;
import org.springframework.messaging.handler.annotation.SendTo;
import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
import org.springframework.stereotype.Controller;

@Controller
public class MessageController {
    @MessageMapping("/chat.sendMessage")
    @SendTo("/topic/public")
    public Message sendMessage(@Payload Message message){
        return message;
    }

    public Message addUser(@Payload Message message,
                           SimpMessageHeaderAccessor headerAccessor){
        //把用户添加到websocket session
        headerAccessor.getSessionAttributes().put("username",message.getSender());
        return message;
    }

}

@SendTo：会将接收到的消息发送到指定的路由目的地，所有订阅该消息的用户都能收到，属于广播。

 

5、添加WebSocket事件监听

创建listener文件夹，在文件夹下添加WebsocketEventListener.java文件：

package com.chen.my_chat.listener;

import com.chen.my_chat.entity.Message;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.event.EventListener;
import org.springframework.messaging.simp.SimpMessageSendingOperations;
import org.springframework.messaging.simp.stomp.StompHeaderAccessor;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.messaging.SessionConnectEvent;

import javax.annotation.Resource;


@Component
public class WebsocketEventListener {
    public static final Logger logger = LoggerFactory.getLogger(WebsocketEventListener.class);

    @Resource
    private SimpMessageSendingOperations messageSendingOperations;

    @EventListener
    public void handleWebSocketConnectListener(SessionConnectEvent event){
        logger.info("接收到一个新的websocket连接");
    }

    @EventListener
    public void handleWebSocketDisConnectListener(SessionConnectEvent event){
        StompHeaderAccessor headerAccessor = StompHeaderAccessor.wrap(event.getMessage());
        String username = (String) headerAccessor.getSessionAttributes().get("username");
        if (username != null){
            logger.info("用户未连接：" + username);
            Message message = new Message();
            message.setType(Message.MessageType.LEAVE);
            message.setSender(username);
            messageSendingOperations.convertAndSend("/topic/public",message);
        }
    }
    
}

6、创建前端网页

index.html:

    
    
    





    

        
Type your username
        

            

                
            
            

                Start Chatting
            
        
    



    

        

            
Spring WebSocket Chat Demo
        
        

            Connecting...
        
        


        
        

            

                

                    
                    Send
                
            
        
    

main.js:

'use strict';

var usernamePage = document.querySelector('#username-page');
var chatPage = document.querySelector('#chat-page');
var usernameForm = document.querySelector('#usernameForm');
var messageForm = document.querySelector('#messageForm');
var messageInput = document.querySelector('#message');
var messageArea = document.querySelector('#messageArea');
var connectingElement = document.querySelector('.connecting');

var stompClient = null;
var username = null;

var colors = [
    '#2196F3', '#32c787', '#00BCD4', '#ff5652',
    '#ffc107', '#ff85af', '#FF9800', '#39bbb0'
];

function connect(event) {
    username = document.querySelector('#name').value.trim();

    if(username) {
        usernamePage.classList.add('hidden');
        chatPage.classList.remove('hidden');

        var socket = new SockJS('/ws');
        stompClient = Stomp.over(socket);

        stompClient.connect({}, onConnected, onError);
    }
    event.preventDefault();
}


function onConnected() {
    // Subscribe to the Public Topic
    stompClient.subscribe('/topic/public', onMessageReceived);

    // Tell your username to the server
    stompClient.send("/app/chat.addUser",
        {},
        JSON.stringify({sender: username, type: 'JOIN'})
    )

    connectingElement.classList.add('hidden');
}


function onError(error) {
    connectingElement.textContent = 'Could not connect to WebSocket server. Please refresh this page to try again!';
    connectingElement.style.color = 'red';
}


function sendMessage(event) {
    var messageContent = messageInput.value.trim();
    if(messageContent && stompClient) {
        var chatMessage = {
            sender: username,
            content: messageInput.value,
            type: 'CHAT'
        };
        stompClient.send("/app/chat.sendMessage", {}, JSON.stringify(chatMessage));
        messageInput.value = '';
    }
    event.preventDefault();
}


function onMessageReceived(payload) {
    var message = JSON.parse(payload.body);

    var messageElement = document.createElement('li');

    if(message.type === 'JOIN') {
        messageElement.classList.add('event-message');
        message.content = message.sender + ' joined!';
    } else if (message.type === 'LEAVE') {
        messageElement.classList.add('event-message');
        message.content = message.sender + ' left!';
    } else {
        messageElement.classList.add('chat-message');

        var avatarElement = document.createElement('i');
        var avatarText = document.createTextNode(message.sender[0]);
        avatarElement.appendChild(avatarText);
        avatarElement.style['background-color'] = getAvatarColor(message.sender);

        messageElement.appendChild(avatarElement);

        var usernameElement = document.createElement('span');
        var usernameText = document.createTextNode(message.sender);
        usernameElement.appendChild(usernameText);
        messageElement.appendChild(usernameElement);
    }

    var textElement = document.createElement('p');
    var messageText = document.createTextNode(message.content);
    textElement.appendChild(messageText);

    messageElement.appendChild(textElement);

    messageArea.appendChild(messageElement);
    messageArea.scrollTop = messageArea.scrollHeight;
}


function getAvatarColor(messageSender) {
    var hash = 0;
    for (var i = 0; i < messageSender.length; i++) {
        hash = 31 * hash + messageSender.charCodeAt(i);
    }
    var index = Math.abs(hash % colors.length);
    return colors[index];
}

usernameForm.addEventListener('submit', connect, true)
messageForm.addEventListener('submit', sendMessage, true)

main.css:

* {
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}

html,body {
    height: 100%;
    overflow: hidden;
}

body {
    margin: 0;
    padding: 0;
    font-weight: 400;
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
    font-size: 1rem;
    line-height: 1.58;
    color: #333;
    background-color: #f4f4f4;
    height: 100%;
}

body:before {
    height: 50%;
    width: 100%;
    position: absolute;
    top: 0;
    left: 0;
    background: #128ff2;
    content: "";
    z-index: 0;
}

.clearfix:after {
    display: block;
    content: "";
    clear: both;
}

.hidden {
    display: none;
}

.form-control {
    width: 100%;
    min-height: 38px;
    font-size: 15px;
    border: 1px solid #c8c8c8;
}

.form-group {
    margin-bottom: 15px;
}

input {
    padding-left: 10px;
    outline: none;
}

h1, h2, h3, h4, h5, h6 {
    margin-top: 20px;
    margin-bottom: 20px;
}

h1 {
    font-size: 1.7em;
}

a {
    color: #128ff2;
}

button {
    box-shadow: none;
    border: 1px solid transparent;
    font-size: 14px;
    outline: none;
    line-height: 100%;
    white-space: nowrap;
    vertical-align: middle;
    padding: 0.6rem 1rem;
    border-radius: 2px;
    transition: all 0.2s ease-in-out;
    cursor: pointer;
    min-height: 38px;
}

button.default {
    background-color: #e8e8e8;
    color: #333;
    box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.12);
}

button.primary {
    background-color: #128ff2;
    box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.12);
    color: #fff;
}

button.accent {
    background-color: #ff4743;
    box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.12);
    color: #fff;
}

#username-page {
    text-align: center;
}

.username-page-container {
    background: #fff;
    box-shadow: 0 1px 11px rgba(0, 0, 0, 0.27);
    border-radius: 2px;
    width: 100%;
    max-width: 500px;
    display: inline-block;
    margin-top: 42px;
    vertical-align: middle;
    position: relative;
    padding: 35px 55px 35px;
    min-height: 250px;
    position: absolute;
    top: 50%;
    left: 0;
    right: 0;
    margin: 0 auto;
    margin-top: -160px;
}

.username-page-container .username-submit {
    margin-top: 10px;
}


#chat-page {
    position: relative;
    height: 100%;
}

.chat-container {
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
    background-color: #fff;
    box-shadow: 0 1px 11px rgba(0, 0, 0, 0.27);
    margin-top: 30px;
    height: calc(100% - 60px);
    max-height: 600px;
    position: relative;
}

#chat-page ul {
    list-style-type: none;
    background-color: #FFF;
    margin: 0;
    overflow: auto;
    overflow-y: scroll;
    padding: 0 20px 0px 20px;
    height: calc(100% - 150px);
}

#chat-page #messageForm {
    padding: 20px;
}

#chat-page ul li {
    line-height: 1.5rem;
    padding: 10px 20px;
    margin: 0;
    border-bottom: 1px solid #f4f4f4;
}

#chat-page ul li p {
    margin: 0;
}

#chat-page .event-message {
    width: 100%;
    text-align: center;
    clear: both;
}

#chat-page .event-message p {
    color: #777;
    font-size: 14px;
    word-wrap: break-word;
}

#chat-page .chat-message {
    padding-left: 68px;
    position: relative;
}

#chat-page .chat-message i {
    position: absolute;
    width: 42px;
    height: 42px;
    overflow: hidden;
    left: 10px;
    display: inline-block;
    vertical-align: middle;
    font-size: 18px;
    line-height: 42px;
    color: #fff;
    text-align: center;
    border-radius: 50%;
    font-style: normal;
    text-transform: uppercase;
}

#chat-page .chat-message span {
    color: #333;
    font-weight: 600;
}

#chat-page .chat-message p {
    color: #43464b;
}

#messageForm .input-group input {
    float: left;
    width: calc(100% - 85px);
}

#messageForm .input-group button {
    float: left;
    width: 80px;
    height: 38px;
    margin-left: 5px;
}

.chat-header {
    text-align: center;
    padding: 15px;
    border-bottom: 1px solid #ececec;
}

.chat-header h2 {
    margin: 0;
    font-weight: 500;
}

.connecting {
    padding-top: 5px;
    text-align: center;
    color: #777;
    position: absolute;
    top: 65px;
    width: 100%;
}


@media screen and (max-width: 730px) {

    .chat-container {
        margin-left: 10px;
        margin-right: 10px;
        margin-top: 10px;
    }
}

@media screen and (max-width: 480px) {
    .chat-container {
        height: calc(100% - 30px);
    }

    .username-page-container {
        width: auto;
        margin-left: 15px;
        margin-right: 15px;
        padding: 25px;
    }

    #chat-page ul {
        height: calc(100% - 120px);
    }

    #messageForm .input-group button {
        width: 65px;
    }

    #messageForm .input-group input {
        width: calc(100% - 70px);
    }

    .chat-header {
        padding: 10px;
    }

    .connecting {
        top: 60px;
    }

    .chat-header h2 {
        font-size: 1.1em;
    }
}

总结

本文基于Websocket特性搭建了一个简易的多人在线聊天室。