【笔记】Gateway统一网关

发表于 2022-10-29 更新于 2023-06-04 阅读次数：

前言

This project provides a library for building an API Gateway on top of Spring WebFlux. Spring Cloud Gateway aims to provide a simple, yet effective way to route to APIs and provide cross cutting concerns to them such as: security, monitoring/metrics, and resiliency.（官网）

引入依赖

pom.xml

<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>

将网关加入到Eureka注册中心

添加依赖

pom.xml

<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>

添加注解

在主启动类添加注解，启动Eureka客户端

package com;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@EnableDiscoveryClient
@SpringBootApplication
public class GatewayApplication {

    public static void main(String[] args) {
        SpringApplication.run(GatewayApplication.class, args);
    }

}

修改配置

src/main/resources/application.yml

server:
  port: 8100
spring:
  application:
    name: gateway
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:8000/eureka

实现请求的路由

添加配置

当请求的路径符合路由的断言规则时，将请求转发到路由的目标路径

spring.cloud.gateway.default-filters：默认过滤器，对所有路由都生效（DefaultFilter）
spring.cloud.gateway.routes.id：路由的id
spring.cloud.gateway.routes.uri：路由的目标路径

lb://服务名：根据服务名发送请求
http://ip地址：根据ip地址发送请求
spring.cloud.gateway.routes.predicates：对指定路由的断言
spring.cloud.gateway.routes.filters：对指定路由的过滤器

src/main/resource/application.yml

spring:
  cloud:
    gateway:
      routes:
        - id: eureka-service-user
          uri: lb://eureka-service-user
          predicates:
            - Path=/users/**
        - id: eureka-service-user
          uri: http://127.0.0.1:8082
          predicates:
            - Path=/orders/**
          filters:
            - AddRequestHeader=key, value
      default-filters:
        - AddRequestHeader=key, value

路由的断言

官方文档

spring.cloud.gateway.routes.predicates.After：指定时间之后
spring.cloud.gateway.routes.predicates.Before：指定时间之前
spring.cloud.gateway.routes.predicates.Between：指定时间之间
spring.cloud.gateway.routes.predicates.Cookie：指定符合条件的Cookie
spring.cloud.gateway.routes.predicates.Header：指定符合条件的Header
spring.cloud.gateway.routes.predicates.Host：指定符合条件的请求域名
spring.cloud.gateway.routes.predicates.Method：指定符合条件的请求方式
spring.cloud.gateway.routes.predicates.Path：指定符合条件的请求地址
spring.cloud.gateway.routes.predicates.Query：指定符合条件的请求参数
spring.cloud.gateway.routes.predicates.RemoteAddr：指定符合条件的请求IP范围
spring.cloud.gateway.routes.predicates.Weight：指定符合条件的组和权重

src/main/resource/application.yml

spring:
  cloud:
    gateway:
      routes:
        - predicates:
          - After=2017-01-20T17:42:47.789-07:00[America/Denver]
          - Before=2017-01-20T17:42:47.789-07:00[America/Denver]
          - Between=2017-01-20T17:42:47.789-07:00[America/Denver], 2017-01-21T17:42:47.789-07:00[America/Denver]
          - Cookie=chocolate, ch.p
          - Header=X-Request-Id, \d+
          - Host=**.somehost.org,**.anotherhost.org
          - Method=GET,POST
          - Path=/red/{segment},/blue/{segment}
          - Query=green
          - RemoteAddr=192.168.1.1/24
          - Weight=group1, 2

路由的过滤器

对请求或响应做处理
官方文档

spring.cloud.gateway.routes.filters.AddRequestHeader：添加请求头
spring.cloud.gateway.routes.filters.RemoveRequestHeader：移除请求头
spring.cloud.gateway.routes.filters.SetRequestHeader：设置请求头

spring.cloud.gateway.routes.filters.AddRequestParameter：添加请求参数
spring.cloud.gateway.routes.filters.RemoveRequestParameter：移除请求参数

spring.cloud.gateway.routes.filters.AddResponseHeader：添加响应头
spring.cloud.gateway.routes.filters.RemoveResponseHeader：移除响应头
spring.cloud.gateway.routes.filters.SetResponseHeader：设置响应头
spring.cloud.gateway.routes.filters.RewriteResponseHeader：重写响应头
spring.cloud.gateway.routes.filters.RewriteLocationResponseHeader：重写响应头中的Location

spring.cloud.gateway.routes.filters.PrefixPath：请求路径添加前缀
spring.cloud.gateway.routes.filters.StripPrefix：请求路径修剪前缀

spring.cloud.gateway.routes.filters.SetPath：设置请求路径
spring.cloud.gateway.routes.filters.RewritePath：重写请求路径

spring.cloud.gateway.routes.filters.RequestHeaderSize：请求头大小
spring.cloud.gateway.routes.filters.RedirectTo：请求转发
spring.cloud.gateway.routes.filters.SaveSession：保存Session
spring.cloud.gateway.routes.filters.SetStatus：设置状态码

src/main/resource/application.yml

spring:
  cloud:
    gateway:
      routes:
        - filters:
          - AddRequestHeader=key, value
          - AddRequestParameter=red, blue
          - AddResponseHeader=X-Response-Red, Blue
          - DedupeResponseHeader=Access-Control-Allow-Credentials Access-Control-Allow-Origin
          - PrefixPath=/mypath
          - RedirectTo=302, https://acme.org
          - RemoveRequestHeader=X-Request-Foo
          - RemoveResponseHeader=X-Response-Foo
          - RemoveRequestParameter=red
          - RequestHeaderSize=1000B
          - RewritePath=/red/?(?<segment>.*), /$\{segment}
          - RewriteLocationResponseHeader=AS_IN_REQUEST, Location, ,
          - RewriteResponseHeader=X-Response-Red, , password=[^&]+, password=***
          - SaveSession
          - SetPath=/{segment}
          - SetRequestHeader=X-Request-Red, Blue
          - SetResponseHeader=X-Response-Red, Blue
          - SetStatus=401
          - StripPrefix=2

全局过滤器（GlobalFilter）

通过注解指定优先级

@Order()：指定过滤器在过滤器链上的优先级，数字越小，优先级越高，范围是[-214783647,214783647]，默认值为最大值，优先级最低

src/main/java/com/filter/AuthorizeFilter.java

package com.filter;

import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.annotation.Order;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.stereotype.Component;
import org.springframework.util.MultiValueMap;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

@Order(0)
@Component
public class AuthorizeFilter implements GlobalFilter {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        // 1. 获取请求参数
        ServerHttpRequest request = exchange.getRequest();
        MultiValueMap<String, String> params = request.getQueryParams();
        // 2. 判断请求参数是否指定参数
        String param = params.getFirst("key");
        if ("value".equals(param)) {
            // 3. 通过链接下一个过滤器链，实现放行
            return chain.filter(exchange);
        }
        // 4. 通过直接返回响应，实现拦截
        // 4.1 根据业务逻辑设置响应码
        exchange.getResponse().setStatusCode(HttpStatus.UNAUTHORIZED);
        // 4.2 返回响应
        return exchange.getResponse().setComplete();
    }
}

通过实现接口指定优先级

通过重写getOrder()方法指定过滤器在过滤器链上的优先级，在返回值中指定，数字越小，优先级越高

src/main/java/com/filter/AuthorizeFilter.java

package com.filter;

import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.stereotype.Component;
import org.springframework.util.MultiValueMap;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

@Component
public class AuthorizeFilter implements GlobalFilter, Ordered {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        // 1. 获取请求参数
        ServerHttpRequest request = exchange.getRequest();
        MultiValueMap<String, String> params = request.getQueryParams();
        // 2. 判断请求参数是否指定参数
        String param = params.getFirst("key");
        if ("value".equals(param)) {
            // 3. 通过链接下一个过滤器链，实现放行
            return chain.filter(exchange);
        }
        // 4. 通过直接返回响应，实现拦截
        // 4.1 根据业务逻辑设置响应码
        exchange.getResponse().setStatusCode(HttpStatus.UNAUTHORIZED);
        // 4.2 返回响应
        return exchange.getResponse().setComplete();
    }

    @Override
    public int getOrder() {
        return 0;
    }
}

过滤器的排序规则

过滤器有三种类型，分别是：全局过滤器、默认过滤器、路由过滤器
在配置文件中定义过滤器时，先配置的过滤器默认权值从1开始依次递增
先比较权值，权值越小，优先级越高
相同权值的过滤器，再比较类型，类型的优先级是：默认过滤器 > 路由过滤器 > 全局过滤器

举例

1	默认过滤器1 > 路由过滤器1 > 全局过滤器1 > 默认过滤器2 > 路由过滤器3

跨域处理

spring.cloud.gateway.globalcors.add-to-simple-url-handler-mapping：解决OPTIONS请求被拦截的问题
spring.cloud.gateway.globalcors.cors-configurations.''：指定哪些请求被跨域处理
spring.cloud.gateway.globalcors.cors-configurations.''.allowedOrigins：指定允许跨域请求的网站
spring.cloud.gateway.globalcors.cors-configurations.''.allowedMethods：指定允许跨域请求的请求类型
spring.cloud.gateway.globalcors.cors-configurations.''.allowedHeaders：指定允许跨域请求的请求头携带信息
spring.cloud.gateway.globalcors.cors-configurations.''.allowCredentials：是否允许携带Cookie
spring.cloud.gateway.globalcors.cors-configurations.''.maxAge：本次跨域检测的有效期

src/main/resources/application.yml

spring:
  cloud:
    gateway:
      globalcors:
        add-to-simple-url-handler-mapping: true
        cors-configurations: 
          '[/**]':
            allowedOrigins:
              - "http://simple.com"
            allowedMethods:
              - "GET"
              - "POST"
              - "DELETE"
              - "PUT"
              - "OPTIONS"
            allowedHeaders: "*"
            allowCredentials: true
            maxAge: 360000