SpringCloud 2.x学习笔记：15、Spring Cloud Gateway之Filter过滤器（Greenwich版本）

1、AddRequestHeader过滤器

server:
  port: 7013
---
spring:
  cloud:
    gateway:
      routes:
      - id: add_request_header_route
        uri: http://httpbin.org
        filters:
        - AddRequestHeader=X-Request-Flag, HelloWorld
        predicates:
        - After=2019-06-20T00:00:00+08:00[Asia/Shanghai]
  profiles: add_request_header_route

http://localhost:7013/get

AddRequestHeaderGatewayFilterFactory的源码

package org.springframework.cloud.gateway.filter.factory;

import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.http.server.reactive.ServerHttpRequest;

/**
 * @author Spencer Gibb
 */
public class AddRequestHeaderGatewayFilterFactory
		extends AbstractNameValueGatewayFilterFactory {

	@Override
	public GatewayFilter apply(NameValueConfig config) {
		return (exchange, chain) -> {
			ServerHttpRequest request = exchange.getRequest().mutate()
					.header(config.getName(), config.getValue()).build();

			return chain.filter(exchange.mutate().request(request).build());
		};
	}

}

从代码可知道，由当前的ServerHttpRequest创建新 ServerHttpRequest ，并在新的ServerHttpRequest加一个请求头，然后创建新的 ServerWebExchange ，提交过滤器链继续过滤。

2、AddRequestHeader过滤器

---
spring:
  cloud:
    gateway:
      routes:
      - id: add_response_header_route
        uri: http://httpbin.org:80/get
        filters:
        - AddResponseHeader=X-Response-Flag, Hadron
        predicates:
        - After=2019-06-20T00:00:00+08:00[Asia/Shanghai]
  profiles: add_response_header_route

C:\Windows\System32>curl -I localhost:7013
HTTP/1.1 200 OK
X-Response-Flag: Hadron
Access-Control-Allow-Credentials: true
Access-Control-Allow-Origin: *
Content-Type: text/html; charset=utf-8
Date: Fri, 21 Jun 2019 09:01:14 GMT
Referrer-Policy: no-referrer-when-downgrade
Server: nginx
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
X-XSS-Protection: 1; mode=block
Content-Length: 0

3、RewritePath 过滤器

---
spring:
  cloud:
    gateway:
      routes:
      - id: rewritepath_route
        uri: https://blog.csdn.net/chengyuqiang
        predicates:
        - Path=/foo/**
        filters:
        - RewritePath=/foo/(?<segment>.*), /$\{segment}
  profiles: rewritepath_route

RewritePath 过滤器将/foo/(?.*)重写为{segment}，然后转发到https://blog.csdn.net。
比如请求http://localhost:7013/foo/chengyuqiang，RewritePath 过滤器将/foo/chengyuqiang重写为chengyuqiang，然后转发到https://blog.csdn.net，这样路径就是https://blog.csdn.net/chengyuqiang

http://localhost:7013/foo/chengyuqiang

4、