import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
@RequestMapping("/user")
public class UserController {
    @ResponseBody
    @RequestMapping("/sayHello")
    public String sayHello(@RequestHeader(value = "sign", 
    required = false) String sign) {
        return "這是好吃的：" + sign;
    }
}

<dependencies>                                                               
    <dependency>                                                             
        <groupId>com.alibaba.cloud</groupId>                                 
        <artifactId>spring-cloud-starter-alibaba-nacos-config
        </artifactId>   
        <version>2.2.0.RELEASE</version>                                     
    </dependency>                                                            
    <dependency>                                                             
        <groupId>com.alibaba.cloud</groupId>                                 
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery
        </artifactId>
        <version>2.2.0.RELEASE</version>                                     
    </dependency>                                                            
    <dependency>                                                             
        <groupId>org.springframework.cloud</groupId>                         
        <artifactId>spring-cloud-starter-gateway</artifactId>                
        <version>2.2.0.RELEASE</version>                                     
    </dependency>                                                            
    <dependency>                                                             
        <groupId>org.projectlombok</groupId>                                 
        <artifactId>lombok</artifactId>                                      
    </dependency>                                                            
</dependencies>                                                              

import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;
import java.util.List;
@Component
public class AuthorizeFilter implements GlobalFilter {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, 
    GatewayFilterChain chain) {
        ServerHttpRequest request = exchange.getRequest();
        HttpHeaders headers = request.getHeaders();
        List<String> sign = headers.get("sign");
        if(sign.size() < 1) {
            ServerHttpResponse response = exchange.getResponse();
            response.setStatusCode(HttpStatus.BAD_REQUEST);
            //被攔截，請(qǐng)求不到對(duì)應(yīng)模塊了
            return exchange.getResponse().setComplete();
        }
        headers = HttpHeaders.writableHttpHeaders(headers);
        headers.set("sign1", "bigAAA");
        //放行
        return chain.filter(exchange);
    }
}