Spring Cloud（十二）Gateway 服务网关

左手的ㄟ右手 2022-11-25 11:50 154阅读 0赞

**Table of Contents**

1.Gateway  介绍

2.pom.xml中添加依赖

3.代码实现

4.Predicate Factory

5.Filter

--------------------

## 1.Gateway  介绍 ##

[https://docs.spring.io/spring-cloud-gateway/docs/2.2.4.RELEASE/reference/html/][https_docs.spring.io_spring-cloud-gateway_docs_2.2.4.RELEASE_reference_html]

在Spring生态系统之上构建的API网关，包括：Spring 5，Spring Boot 2和Project Reactor。Spring Cloud Gateway旨在提供一种简单而有效的方法来路由到API，并为它们提供跨领域关注，例如：安全性，监视/指标和弹性。

SpringCloud Gateway作为Spring Cloud生态系统中的网关,目标是替代Zuul, 在Spring Cloud 2.0以上版本中,没有对新版本的Zuul 2.0以上最新高性能版本进行集成,仍然还是使用的Zuul 1.x非Reactor模式的老版本。而为了提升网关的性能, SpringCloud Gateway是基于WebFlux框架实现的,而WebFlux框架底层则使用了高性能的Reactor模式通信框架Netty。

Spring Cloud Gateway的目标提供统一的路由方式且基于Filter链的方式提供了网关基本的功能,例如:安全,监控/指标,和限流。

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客户端向Spring Cloud Gateway发出请求。如果网关处理程序映射确定请求与路由匹配，则将其发送到网关Web处理程序。该处理程序通过特定于请求的过滤器链运行请求。筛选器由虚线分隔的原因是，筛选器可以在发送代理请求之前和之后运行逻辑。所有“前置”过滤器逻辑均被执行。然后发出代理请求。发出代理请求后，将运行“后”过滤器逻辑。

**Route(路由)：**  
是构建网关的基本模块,它由ID,目标URI,一系列的断言和过滤器组成,如果断言为true则匹配该路由  
**Predicate(断言)：**  
参考的是Java8的java.util.function.Predicate，开发人员可以匹配HTTP请求中的所有内容(例如请求头或请求参数),如果请求与断言相匹配则进行路由  
**Filter(过滤)：**  
指的是Spring框架中GatewayFilter的实例,使用过滤器,可以在请求被路由前或者之后对请求进行修改

## 2.pom.xml中添加依赖 ##

<dependencies>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-gateway</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
            <dependency>
                <groupId>com.ak.demo</groupId>
                <artifactId>api-commons</artifactId>
                <version>${project.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
                <scope>runtime</scope>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
            </dependency>
        </dependencies>

## 3.代码实现 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjAzMjE5OQ_size_16_color_FFFFFF_t_70 1][]

server:
      port: 9527
    
    spring:
      application:
        name: gateway-service
      cloud:
        gateway:
          discovery:
            locator:
              enabled: true #开启从注册中心动态创建路由的功能，利用微服务名进行路由
          routes:
            - id: payment_routh #路由ID，没有固定规则但要求唯一，建议配合服务名
    #          uri: http://localhost:8001 #匹配后提供服务的路由地址
              uri: lb://PAYMENT-SERVICE	 #匹配后提供服务的路由地址，负载均衡
              predicates:
                - Path=/payment/get/** #断言，路径相匹配的进行路由
            - id: payment_routh2 #路由ID，没有固定规则但要求唯一，建议配合服务名
    #          uri: http://localhost:8001 #匹配后提供服务的路由地址
              uri: lb://PAYMENT-SERVICE     #匹配后提供服务的路由地址，负载均衡
              predicates:
                - Path=/payment/LB/** #断言，路径相匹配的进行路由
    
    eureka:
      client:
        register-with-eureka: true #表示向注册中心注册自己 默认为true
        fetch-registry: true #是否从EurekaServer抓取已有的注册信息，默认为true,单节点无所谓,集群必须设置为true才能配合ribbon使用负载均衡
        service-url:
    #      defaultZone: http://eureka7001.com:7001/eureka/, http://eureka7002.com:7002/eureka/ # 入驻集群地址
          defaultZone: http://eureka7001.com:7001/eureka/
      instance:
        hostname: gateway-service

@EnableEurekaClient
    @SpringBootApplication
    public class Gateway9527 {
        public static void main(String[] args) {
            SpringApplication.run(Gateway9527.class,args);
        }
    }

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**可以编码代替yml，参考官网**

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@Bean
    public RouteLocator routes(RouteLocatorBuilder builder) {
        return builder.routes()
            .route("circuitbreaker_route", r -> r.path("/consumingServiceEndpoint")
                .filters(f -> f.circuitBreaker(c -> c.name("myCircuitBreaker").fallbackUri("forward:/inCaseOfFailureUseThis").addStatusCode("INTERNAL_SERVER_ERROR"))
                    .rewritePath("/consumingServiceEndpoint", "/backingServiceEndpoint")).uri("lb://backing-service:8088")
            .build();
    }

## 4.Predicate Factory ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjAzMjE5OQ_size_16_color_FFFFFF_t_70 3][]

## 5.Filter ##

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![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjAzMjE5OQ_size_16_color_FFFFFF_t_70 5][]

@Bean
    public GlobalFilter customFilter() {
        return new CustomGlobalFilter();
    }
    
    public class CustomGlobalFilter implements GlobalFilter, Ordered {
    
        @Override
        public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
            log.info("custom global filter");
            return chain.filter(exchange);
        }
    
        @Override
        public int getOrder() {
            return -1;
        }
    }

[https_docs.spring.io_spring-cloud-gateway_docs_2.2.4.RELEASE_reference_html]: https://docs.spring.io/spring-cloud-gateway/docs/2.2.4.RELEASE/reference/html/
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