网关API(SpringCloudGateway)如何自定义Filter

在Spring Cloud Gateway中，自定义过滤器可以通过实现GatewayFilterFactory接口来完成。以下是一个简单的自定义过滤器的例子，它会在请求的路径上添加一个前缀。

1. 创建一个新的类实现GatewayFilterFactory接口：

import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpRequestDecorator;
import org.springframework.stereotype.Component;
 
@Component
public class AddPrefixGatewayFilterFactory extends AbstractGatewayFilterFactory<AddPrefixGatewayFilterFactory.Config> {
    private static final String PREFIX_KEY = "prefix";
 
    public AddPrefixGatewayFilterFactory() {
        super(Config.class);
    }
 
    @Override
    public List<String> shortcutFieldOrder() {
        return Arrays.asList(PREFIX_KEY);
    }
 
    @Override
    public GatewayFilter apply(Config config) {
        return (exchange, chain) -> {
            String prefix = config.getPrefix();
            String path = exchange.getRequest().getURI().getPath();
            if (!path.startsWith(prefix)) {
                path = prefix + path;
                ServerHttpRequest mutatedRequest = mutate(exchange)
                        .request(r -> r.mutate()
                                .path(path)
                                .build())
                        .build();
                return chain.filter(exchange.mutate().request(mutatedRequest).build());
            }
            return chain.filter(exchange);
        };
    }
 
    public static class Config {
        private String prefix;
 
        public String getPrefix() {
            return prefix;
        }
 
        public void setPrefix(String prefix) {
            this.prefix = prefix;
        }
    }
}

2. 在application.yml配置文件中使用自定义的过滤器：

spring:
  cloud:
    gateway:
      routes:
      - id: add_prefix_route
        uri: https://example.org
        filters: