WebSocket 从入门到进阶实战

好记忆不如烂笔头，能记下点东西，就记下点，有时间拿出来看看，也会发觉不一样的感受.

聊天系统是WebSocket的最佳实践，以下是使用WebSocket技术实现的一个聊天系统的关键代码，可以通过这些关键代码，更加清晰的了解 WebSocket 在项目中的使用情况（本实战将以springboot框架进行展开）。

一、前端代码（HTML + JavaScript）

前端页面：chat.html

二、Java 后端代码（Spring Boot）

1. 添加依赖

2. 配置 WebSocket

3. 创建 WebSocket 服务端类

4. 创建 Spring Boot 应用主类

三、异常处理和性能优化

1. 异常处理

2. 性能优化

四、运行和测试

五、总结

一、前端代码（HTML + JavaScript）

前端页面：`chat.html`

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>实时聊天室</title><style>body {font-family: Arial, sans-serif;margin: 0;padding: 0;display: flex;flex-direction: column;align-items: center;justify-content: center;height: 100vh;background-color: #f4f4f4;}#chat-container {width: 80%;max-width: 600px;background: white;border-radius: 8px;box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);overflow: hidden;}#chat-header {background: #007bff;color: white;padding: 10px;text-align: center;font-size: 1.5em;}#chat-body {height: 300px;overflow-y: auto;padding: 10px;border-bottom: 1px solid #ddd;}#chat-footer {display: flex;padding: 10px;}#chat-footer input {flex: 1;padding: 8px;border: 1px solid #ddd;border-radius: 4px;margin-right: 10px;}#chat-footer button {padding: 8px 16px;border: none;background: #007bff;color: white;border-radius: 4px;cursor: pointer;}#chat-footer button:hover {background: #0056b3;}.message {margin-bottom: 10px;}.message .username {font-weight: bold;}</style>
</head>
<body><div id="chat-container"><div id="chat-header">实时聊天室</div><div id="chat-body"></div><div id="chat-footer"><input type="text" id="message-input" placeholder="输入消息..."><button onclick="sendMessage()">发送</button></div></div><script>const chatBody = document.getElementById('chat-body');const messageInput = document.getElementById('message-input');let webSocket = null;// 连接 WebSocket 服务器function connect() {if ('WebSocket' in window) {webSocket = new WebSocket("ws://localhost:8080/chat");webSocket.onopen = function() {console.log("已连接到服务器");};webSocket.onmessage = function(event) {const message = JSON.parse(event.data);displayMessage(message);};webSocket.onclose = function() {console.log("连接已关闭");};webSocket.onerror = function(error) {console.error("WebSocket 发生错误：", error);};} else {alert("您的浏览器不支持 WebSocket！");}}// 发送消息function sendMessage() {const messageText = messageInput.value.trim();if (messageText) {const message = {username: "用户" + Math.floor(Math.random() * 100), // 模拟用户名text: messageText};webSocket.send(JSON.stringify(message));messageInput.value = '';}}// 显示消息function displayMessage(message) {const messageElement = document.createElement('div');messageElement.classList.add('message');messageElement.innerHTML = `<span class="username">${message.username}:</span> ${message.text}`;chatBody.appendChild(messageElement);chatBody.scrollTop = chatBody.scrollHeight; // 滚动到底部}// 页面加载时连接 WebSocketwindow.onload = connect;</script>
</body>
</html>

二、Java 后端代码（Spring Boot）

1. 添加依赖

在 pom.xml 文件中添加 WebSocket 依赖：

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-websocket</artifactId>
</dependency>

2. 配置 WebSocket

创建一个配置类 WebSocketConfig：

package com.example.websocket.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;@Configuration
public class WebSocketConfig {@Beanpublic ServerEndpointExporter serverEndpointExporter() {return new ServerEndpointExporter();}
}

3. 创建 WebSocket 服务端类

创建一个 WebSocket 服务端类 ChatServer：

package com.example.websocket.server;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;@ServerEndpoint("/chat")
@Component
public class ChatServer {private static final Logger log = LoggerFactory.getLogger(ChatServer.class);private static final Set<Session> sessions = Collections.synchronizedSet(new HashSet<>());@OnOpenpublic void onOpen(Session session) {sessions.add(session);log.info("新用户连接: " + session.getId());sendMessageToAll("系统通知: 有新用户加入了聊天室！");}@OnMessagepublic void onMessage(String message, Session session) {log.info("收到来自用户的消息: " + message);sendMessageToAll(message);}@OnClosepublic void onClose(Session session) {sessions.remove(session);log.info("用户断开连接: " + session.getId());sendMessageToAll("系统通知: 有用户离开了聊天室！");}@OnErrorpublic void onError(Session session, Throwable throwable) {log.error("WebSocket 发生错误: " + throwable.getMessage());sessions.remove(session);}// 向所有用户发送消息private void sendMessageToAll(String message) {synchronized (sessions) {for (Session session : sessions) {if (session.isOpen()) {try {session.getBasicRemote().sendText(message);} catch (IOException e) {log.error("发送消息时发生错误: " + e.getMessage());}}}}}
}

4. 创建 Spring Boot 应用主类

创建一个主类 ChatApplication：

package com.example.websocket;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class ChatApplication {public static void main(String[] args) {System.out.println("聊天系统正在启动");SpringApplication.run(ChatApplication.class, args);System.out.println("聊天系统启动完成");}
}