springboot项目 使用websocket

Spring Boot项目中使用WebSocket可以实现实时双向通信，比如聊天应用、在线通知等。WebSocket是一种在单个TCP连接上进行全双工通信的技术。以下是使用Spring Boot和WebSocket的基本步骤：

1. 添加依赖：在你的`pom.xml`或`build.gradle`文件中添加WebSocket相关依赖，例如Spring Websocket的`spring-boot-starter-websocket`。

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

<!-- Gradle (Kotlin) -->
dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-websocket'
}

2. 配置WebSocket：在`application.properties`或`application.yml`中配置WebSocket服务器端点，如`server.webSocket.port`。

3. 创建WebSocket控制器：创建一个实现了`WebsocketHandler`接口的类，这是处理WebSocket连接和消息的地方。

import org.springframework.messaging.handler.annotation.MessageMapping;
import org.springframework.messaging.simp.SimpMessageSendingOperations;
import org.springframework.stereotype.Component;

@Component
public class ChatWebSocketHandler implements WebsocketHandler {

    @Override
    public void afterConnectionEstablished(WebSocketSession session) {
        // 在连接建立后执行的操作
    }

    @MessageMapping("/chat")
    public String handleMessage(String message) {
        // 处理接收到的消息并返回响应
    }

    @SendTo("/topic/chat")
    public String sendMessage(String message) {
        // 发送消息到所有连接的客户端
        return "Message sent to all!";
    }
}

4. 注册WebSocket处理器：在`WebMvcConfigurer`中注册WebSocket处理器，使之被Spring扫描和启用。

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 configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/topic");
        config.setApplicationDestinationPrefixes("/app");
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/ws").withSockJS();
    }
}