探索Spring Cloud Gateway与WebSocket结合的新可能

import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;
 
import java.nio.charset.StandardCharsets;
 
public class WebsocketGatewayFilter implements GlobalFilter, Ordered {
 
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerHttpRequest request = exchange.getRequest();
        ServerHttpResponse response = exchange.getResponse();
 
        // 检查请求是否为WebSocket Upgrade请求
        if (isWebSocketUpgradeRequest(request)) {
            // 修改请求头部，允许WebSocket Upgrade
            response.getHeaders().set("Upgrade", "websocket");
            response.getHeaders().set("Connection", "Upgrade");
 
            // 返回一个空的响应体，实际的WebSocket交互在Upgrade后进行
            return response.setComplete();
        }
 
        // 不是WebSocket Upgrade请求，继续请求链
        return chain.filter(exchange);
    }
 
    private boolean isWebSocketUpgradeRequest(ServerHttpRequest request) {
        // 检查请求方法是否为GET
        if ("GET".equals(request.getMethodValue())) {
            // 检查请求头部是否包含 "Upgrade: websocket"
            return "websocket".equals(request.getHeaders().getUpgrade());
        }
        return false;
    }
 
    @Override
    public int getOrder() {
        // 确保此过滤器在路由之前运行
        return -1;
    }
}

这段代码实现了一个全局过滤器，用于检查进入网关的请求是否是WebSocket的升级请求。如果是，它会修改响应头部，允许客户端进行WebSocket升级，并返回一个空的响应体。这样的过滤器可以用于实现WebSocket代理的场景，在网关层面接入WebSocket连接，并可能与WebSocket路由功能结合，以便在网关层面处理WebSocket事件。