Springboot+WebSocket实现消息推送

以下是一个使用Spring Boot和WebSocket实现消息推送的简单示例：

1. 添加依赖到你的pom.xml：

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

2. 配置WebSocket：

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.enableSimpleBroker("/topic");
        registry.setApplicationDestinationPrefixes("/app");
    }
}

3. 创建控制器来处理WebSocket消息：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.handler.annotation.MessageMapping;
import org.springframework.messaging.handler.annotation.SendTo;
import org.springframework.stereotype.Controller;
 
@Controller
public class WebSocketController {
 
    @Autowired
    private SimpMessagingTemplate simpMessagingTemplate;
 
    @MessageMapping("/sendMessage")
    public void sendMessage(String message) {
        simpMessagingTemplate.convertAndSend("/topic/public", message);
    }
}

4. 前端JavaScript代码来连接WebSocket并接收消息：

var socket = new SockJS('/ws');
stompClient = Stomp.over(socket);
stompClient.connect({}, function (frame) {
    console.log('Connected: ' + frame);
    stompClient.subscribe('/topic/public', function (message) {
        showMessage(JSON.parse(message.body).content);
    });
});
 
function showMessage(message) {
    var messageElement = document.createElement('p');
    messageElement.textContent = message;
    document.getElementById('messages').appendChild(messageElement);
}

确保你的Spring Boot应用程序已经启动，并且前端JavaScript代码在一个HTML页面上运行。当你发送一个消息到/sendMessage端点时，所有连接到/topic/public的客户端都会收到这个消息。