使用Websocket进行前后端实时通信

1、引入jar,spring-websocket-starter

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

2、配置websocket config

import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
 
@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(myHandler(), "/myEndpoint").setAllowedOrigins("*");
    }
 
    public WebSocketHandler myHandler() {
        return new MyWebSocketHandler();
    }
}

3、使用实现websocket handler

import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;
 
public class MyWebSocketHandler extends TextWebSocketHandler {
    @Override
    public void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        System.out.println("Received: " + message.getPayload());
        session.sendMessage(new TextMessage("Hello from server"));
    }
}

4、前端使用

<script>
    var socket = new WebSocket("ws://localhost:8080/myEndpoint");
    socket.onmessage = function(event) {
        console.log('Received from server:', event.data);
    };
    socket.onopen = function() {
        socket.send('Hello Server');
    };
</script>

### WebSocket 实现前后端实时通信教程 #### 1. 前提条件 为了实现WebSocket前后端实时通信,需要确保环境已经配置好Java开发工具包(JDK),并安装了Maven来管理项目的依赖项。 #### 2. 后端设置 (基于Spring Boot) 创建一个新的Spring Boot应用程序,并在`pom.xml`文件中引入必要的依赖库[^2]: ```xml <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-websocket</artifactId> </dependency> ``` 定义一个简单的WebSocket控制器类,用来处理来自客户端的消息以及向其广播消息: ```java import org.springframework.context.annotation.Configuration; import org.springframework.messaging.handler.annotation.MessageMapping; import org.springframework.messaging.handler.annotation.SendTo; import org.springframework.stereotype.Controller; @Controller public class WebSocketController { @MessageMapping("/sendMessage") @SendTo("/topic/messages") public String handleMessage(String message) { return "Received Message: " + message; } } ``` 注册上述组件并通过启用WebSocket支持完成配置工作。可以在主应用类或单独的配置类里添加如下代码片段: ```java @Configuration @EnableWebSocketMessageBroker public class WebSocketConfig implements WebSocketMessageBrokerConfigurer { @Override public void configureMessageBroker(MessageBrokerRegistry config) { config.enableSimpleBroker("/topic"); config.setApplicationDestinationPrefixes("/app"); } @Override public void registerStompEndpoints(StompEndpointRegistry registry) { registry.addEndpoint("/ws").withSockJS(); } } ``` #### 3. 客户端设置 对于前端部分,这里采用HTML页面配合JavaScript脚本来演示如何连接至服务器并向之发送/接收信息。首先,在网页内加入sockjs-client和stomp.js这两个库的支持;接着编写初始化逻辑与事件监听函数。 ```html <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>WebSocket Demo</title> <script src="https://cdn.jsdelivr.net/npm/sockjs-client@1/dist/sockjs.min.js"></script> <script src="https://cdn.jsdelivr.net/npm/stompjs/lib/stomp.min.js"></script> <body> <div id="messages"></div> <input type="text" id="messageInput"/> <button onclick="send()">Send</button> <script> var stompClient = null; function connect() { var socket = new SockJS('/ws'); stompClient = Stomp.over(socket); stompClient.connect({}, function(frame) { console.log('Connected: ' + frame); stompClient.subscribe('/topic/messages', function(messageOutput) { showMessage(JSON.parse(messageOutput.body).content); }); }); } function send() { var message = document.getElementById('messageInput').value; stompClient.send("/app/sendMessage", {}, JSON.stringify({'content': message})); } function showMessage(message) { var messagesArea = document.getElementById('messages'); messagesArea.innerHTML += "<br/>" + message; } connect(); // 自动尝试连接到WebSocket服务端口 </script> </body> </html> ``` 这段示例展示了怎样利用WebSocket技术构建起一套完整的即时通讯机制——从前端界面收集用户输入的信息,经由STOMP协议传递给后端处理器,再由后者负责分发响应结果回传给所有已订阅对应频道的客户终端显示出来[^4]。
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