There are many built-in filter factories in Gateway. Through some filter factories, we can carry out some business logic processors, such as adding and removing response headers, adding and removing parameters, etc

Filter factory official website: https://docs.spring.io/spring-cloud-gateway/docs/current/reference/html/#gatewayfilter-factories

Filter factory	effect	parameter
AddRequestHeader	Add Header for original request	Name and value of Header
AddRequestParameter	Add request parameters to the original request	Parameter name and value
AddResponseHeader	Add Header for original response	Name and value of Header
DedupeResponseHeader	Eliminate duplicate values in response headers	Header name and de duplication policy that need to be de duplicated
Hystrix	Introduce circuit breaker protection of Hystrix for routing	The name of the HystrixCommand
FallbackHeaders	Add specific exception information to the request header of fallbackUri	The name of the Header
PrefixPath	Prefix the original request path	prefix path
PreserveHostHeader	The routing filter checks this property to determine whether to send the original Host	nothing
RequestRateLimiter	It is used to limit the current of requests. The current limiting algorithm is token bucket	keyResolver,rateLimiter,statusCode, denyEmptyKey,emptyKeyStatus
RedirectTo	Redirect the original request to the specified URL	http status code and redirected url
RemoveHopByHopHeadersFilter	Delete a series of headers specified by IETF organization for the original request	It will be enabled by default. You can specify which headers to delete only through configuration
RemoveRequestHeader	Delete a Header for the original request	Header name
RemoveResponseHeader	Delete a Header for the original response	Header name
RewritePath	Rewrite the original request path	Regular expressions of original path and rewritten path
RewriteResponseHeader	Override a Header in the original response	Header name, regular expression of value, rewritten value
SaveSession	Force the WebSession::save operation before forwarding the request	nothing
secureHeaders	Add a series of security response headers to the original response	None. It supports modifying the values of these security response headers
SetPath	Modify the original request path	Modified path
SetResponseHeader	Modify the value of a Header in the original response	Modify the value of a Header in the original response, the Header name, and the modified value
SetStatus	Modify the status code of the original response	HTTP status code, which can be a number or a string
StripPrefix	The path used to truncate the original request	Use a number to indicate the number of paths to truncate
Retry	Retry for different responses	retries,statuses,methods,series
RequestSize	Sets the size of the maximum request packet allowed to be received. If the requested packet size exceeds the set value, 413 Payload Too Large is returned	The size of the request packet, in bytes. The default value is 5M
ModifyRequestBody	Modify the content of the original request body before forwarding the request	Modified request body content
ModifyResponseBody	Modify the content of the original response body	Modified response body content

1.1 add request header

In the gateway module

server:
  port: 8070
spring:
  application:
    name: api-gateway
  cloud:
    #gateway configuration
    gateway:
      #Routing configuration [routing is to specify which micro service to go to when the request meets what conditions]
      routes:
        - id: order_route #The unique identifier of the route to order
          uri: lb://Order service # refers to the address to be forwarded. lb refers to the microservices obtained from nacos by name and following the load balancing policy
          #Assertion rules are the conditions to be met by routing and forwarding
          predicates:
            # When client access http://localhost:8070/order/add Route to ↓
            #  http://localhost:8081/order/add
            - Path=/order/** #When the request Path meets the rules specified by Path, route forwarding is carried out
          filters: #Filter. The request can be modified through the filter during transmission
            - AddRequestHeader=X-Request-color, blue #Add request header
    #Configure nacos
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
        username: nacos
        password: nacos

In order sub module

package com.example.order.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
@RequestMapping("/order")
public class OrderController {

    @Autowired
    private RestTemplate restTemplate;

    @RequestMapping("/add")
    public String add(){
        System.out.println("checkout success ");
        String forObject = restTemplate.getForObject("http://stock-service/stock/reduck", String.class);
        return "Hello World " + forObject;
    }

    @RequestMapping("/header")
    public String header(@RequestHeader("X‐Request‐color") String color){
        return color;
    }
}

Start test

Start the nacos, order, stock and gateway modules

visit: http://localhost:8070/order/header

1.2 add prefixes to matching routes

In the gateway module

In order sub module

server:
  port: 8081
  servlet:
    context-path: /myorder
#Application name (nacos will take this name as the service name)
spring:
  application:
    name: order-service
  cloud:
    nacos:
      server-addr: 127.0.0.1:8848
      discovery:
        username: nacos
        password: nacos
        namespace: public

Start test

Start the nacos, order, stock and gateway services

visit: http://localhost:8070/order/add