前言

在上一篇文章中简单的介绍了SpringCloud Gateway，同时也对比了一下springcloud的gateway和Netflix的zuul，相信大家也有了一定的认识。此篇文章主要介绍一下gateway是如何配置的。同其他

一、引入pom依赖

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

二、配置文件

1、路由配置

spring:
  application:
    name: gateway
  profiles: 
    active: dev
  cloud:
    gateway:
      discovery:
        locator:
          enabled: true
          lower-case-service-id: true
      routes:
      - id: foo # foo服务
        uri: lb://integral-foo
        predicates:
        - Path=/foo-web/**
        filters:
        - StripPrefix=1
server:
  port: 1001
eureka:
  instance:
    instance-id: ${ spring.application.name}:${ random.int}
    prefer-ip-address: true
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka

routes：具体的路由信息，是一个数组
- id：这个路由的唯一id，不定义的话默认为一个uuid
- uri：http请求为lb://前缀+服务id；ws请求为lb//前缀+服务id，表示将请求负载到哪个服务上
- predicates：表示这个路由的请求匹配规则，只有符合这个规则的请求才会走这个路由。每个规则为并且的关系。
- filters：请求转发前的filter
- order：这个路由的执行order

2、跨域配置

spring:
  application:
    name: gateway
  profiles:
    active: dev
  cloud:
    gateway:
      globalcors:
        corsConfigurations:
           '[/**]':
              maxAge: 1800
              allowedOrigins: "*"
              allowCredentials: true
              allowedMethods:
              - GET
              - POST
              - PUT
              - DELETE

allowedOrigins：允许的请求
allowCredentials：允许凭证
allowedMethods：允许的方法请求方式

关于跨域的配置SpringCloud Gateway官网上写的已经很详细了。但是有一点没有提到，前后端交互的时候OPTIONS请求没有跨过去，yml文件里面只能配置get，post，put，delete等等这些请求，配置了OPTIONS不起作用。那么就需要我们再添加一个配置类来专门处理OPTIONS请求。

/** * @author 刘子腾 * @DESCRIPTION 网关跨域 * @create 2019/3/12 */
@Configuration
public class CorsConfig { 
    private static final String ALL = "*";
    private static final String MAX_AGE = "18000";
    @Bean
    public WebFilter corsFilter() { 
        return (ServerWebExchange ctx, WebFilterChain chain) -> { 
            ServerHttpRequest request = ctx.getRequest();
            if (!CorsUtils.isCorsRequest(request)) { 
                return chain.filter(ctx);
            }
            HttpHeaders requestHeaders = request.getHeaders();
            ServerHttpResponse response = ctx.getResponse();
            HttpMethod requestMethod = requestHeaders.getAccessControlRequestMethod();
            HttpHeaders headers = response.getHeaders();
            headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN, requestHeaders.getOrigin());
            headers.addAll(HttpHeaders.ACCESS_CONTROL_ALLOW_HEADERS, requestHeaders.getAccessControlRequestHeaders());
            if (requestMethod != null) { 
                headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_METHODS, requestMethod.name());
            }
            headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_CREDENTIALS, "true");
            headers.add(HttpHeaders.ACCESS_CONTROL_EXPOSE_HEADERS, ALL);
            headers.add(HttpHeaders.ACCESS_CONTROL_MAX_AGE, MAX_AGE);
            if (request.getMethod() == HttpMethod.OPTIONS) { 
                response.setStatusCode( HttpStatus.OK);
                return Mono.empty();
            }
            return chain.filter(ctx);
        };
    }
}

三、重要的filter

1、StripPrefix

spring:
  cloud:
    gateway:
      routes:
      - id: nameRoot
        uri: lb://nameservice
        predicates:
        - Path=/name/**
        filters:
        - StripPrefix=1

/name/bar/foo的请求会被转发为http://nameserviceip:nameserviceport/bar/foo

2、Hystrix熔断

1）引入pom依赖

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

2）配置文件

spring:
  cloud:
    gateway:
      default-filters:
      routes:
      #------------------------------------------------------------------------
      - id: i5xforyou-biz-auth
        uri: lb://i5xforyou-biz-auth
        predicates:
        - Path= ${ server.servlet.context-path}/auth/**
        filters:
        - StripPrefix= 1
        - name: Hystrix
          args:
            name: authHystrixCommand
            fallbackUri: forward:/hystrixTimeout
#设置断路由的超时时间，毫秒
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds= 30000

name表示HystrixCommand代码的名称，fallbackUri表示触发断路由后的跳转请求url

3、自定义gateway filter

自定义一个用来检验jwt是否合法的gateway filter为例进行说明。

1）定义一个JwtCheckGatewayFilterFactory类实现GatewayFilterFactory接口。
类名一定要为filterName + GatewayFilterFactory，如这里定义为JwtCheckGatewayFilterFactory的话，它的filterName就是JwtCheck

2）实现gateway filter的业务逻辑

@Component
public class JwtCheckGatewayFilterFactory extends AbstractGatewayFilterFactory<Object> { 
    @Override
    public GatewayFilter apply(Object config) { 
        return (exchange, chain) -> { 
            //return chain.filter(exchange);
            String jwtToken = exchange.getRequest().getHeaders().getFirst("Authorization");
            //校验jwtToken的合法性
            if (JwtUtil.verifyToken(jwtToken) != null) { 
                //合法
                return chain.filter(exchange);
            }
            //不合法
            ServerHttpResponse response = exchange.getResponse();
            //设置headers
            HttpHeaders httpHeaders = response.getHeaders();
            httpHeaders.add("Content-Type", "application/json; charset=UTF-8");
            httpHeaders.add("Cache-Control", "no-store, no-cache, must-revalidate, max-age=0");
            //设置body
            JsonPackage jsonPackage = new JsonPackage();
            jsonPackage.setStatus(110);
            jsonPackage.setMessage("未登录或登录超时");
            DataBuffer bodyDataBuffer = response.bufferFactory().wrap(jsonPackage.toJSONString().getBytes());
            return response.writeWith(Mono.just(bodyDataBuffer));
        };
    }
}

3）配置文件

spring:
  cloud:
    gateway:
      default-filters:
      routes:
      #------------------------------------------------------------------------
      - id: i5xforyou-biz-auth
        uri: lb://i5xforyou-biz-auth
        predicates:
        - Path= ${ server.servlet.context-path}/auth/**
        filters:
        - StripPrefix= 1
        - JwtCheck