如何通过ClientEndpointConfig.Configurator在@OnOpen动态给websocket请求添加请求头

在WebSocket应用程序中，如果你想要在`@OnOpen`注解处理函数启动时动态添加请求头到WebSocket连接上，你可以利用Spring WebSocket提供的`ClientEndpointConfig.Configurator`接口。这是一个自定义配置类，允许你在连接建立之前修改连接属性。

首先，创建一个实现了`ClientEndpointConfig.Configurator`接口的类：

import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.support.MessageHeaderAccessor;
import org.springframework.web.socket.client.WebSocketClient;
import org.springframework.web.socket.config.ClientTransportConfiguration;
import org.springframework.web.socket.config.ClientWebSocketInterceptor;

@Configuration
public class CustomWebSocketConfig implements ClientEndpointConfig.Configurator {

    @Override
    public void beforeRequest(WebSocketClient webSocketClient, ClientTransportConfiguration transportConfiguration,
                              ClientWebSocketInterceptor[] interceptors) {
        // 获取当前的WebSocket请求
        ClientWebSocket request = webSocketClient.doHandshake(interceptors[0].getHandshakeHandler().createRequest(),
                transportConfiguration.getUpgradeTarget());

        // 添加自定义请求头
        MessageHeaderAccessor.getRequestHeaders(request).add("Custom-Header", "YourHeaderValue");
    }
}

然后，在你的Spring Boot应用中启用此配置，并注入到需要的地方：

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig extends StompWebsocketConfigurer {

    @Autowired
    private CustomWebSocketConfig customWebSocketConfig;

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        // ...其他配置
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/your-websocket-endpoint").withSockJS();
    }

    @Bean
    public ClientWebSocketInterceptor customInterceptor() {
        return new ClientWebSocketInterceptor(customWebSocketConfig);
    }
}

这样，每次新的WebSocket连接打开时，都会自动添加名为"Custom-Header"的请求头，值为你在`beforeRequest`方法中指定的"YourHeaderValue"。