SpringCloud 入门教程(九)：路由网关zuul

在微服务架构中，需要几个关键的组件，服务注册与发现、服务消费、负载均衡、断路器、智能路由、配置管理等，由这几个组件可以组建一个简单的微服务架构。客户端的请求首先经过负载均衡（zuul、Ngnix），再到达服务网关（zuul集群），然后再到具体的服务，服务统一注册到高可用的服务注册中心集群，服务的所有的配置文件由配置服务管理（下一篇文章讲述），配置服务的配置文件放在Git仓库，方便开发人员随时改配置。

1. Zuul介绍

Zuul的主要功能是路由和过滤器。路由功能是微服务的一部分，比如／api/user映射到user服务，/api/shop映射到shop服务。zuul实现了负载均衡。以下是微服务结构中，Zuul的基本流程。在接下来的步骤中，我们来创建一个zuul服务，将/api-feign/**映射到我们之前创建feign-service, 将/api-ribbon/**映射到之前的ribbon-service服务。

2. 创建Zuul的Maven工程，其中关于zuul的依赖是

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

完整pom.xml如下：

  <?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>cm.chry</groupId><artifactId>spring.helloworld.zuul.service</artifactId><version>0.0.1-SNAPSHOT</version><name>spring.helloworld.zuul.service</name><description>zuul service demo</description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.5.3.RELEASE</version><relativePath/> <!-- lookup parent from repository --></parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-zuul</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>Dalston.RC1</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build><repositories><repository><id>spring-milestones</id><name>Spring Milestones</name><url>https://repo.spring.io/milestone</url><snapshots><enabled>false</enabled></snapshots></repository></repositories></project>

3. 创建启动类: 使用@EnableZuulProxy注解

 package spring.helloworld.zuul.service;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.netflix.eureka.EnableEurekaClient;import org.springframework.cloud.netflix.zuul.EnableZuulProxy;@EnableZuulProxy@EnableEurekaClient@SpringBootApplicationpublic class ServiceZuulApplication {public static void main(String[] args) {SpringApplication.run(ServiceZuulApplication.class, args);}}

4. 编写zuul服务配置：

简单配置两个路由，一个路由到ribbon，一个路由到feign；由于都注册到eureka服务中心，所以都用通过serviceId来发现服务具体地址， path是路由的地址映射关系

 eureka:client:serviceUrl:defaultZone: http://localhost:8761/eureka/server:port: 8904spring:application:name: service-zuulzuul:routes:ribbo:path: /api-ribbon/**serviceId: service-ribbonfeign:path: /api-feign/**serviceId: service-feign

这时启动zuul服务，然后访问http://localhost:8904/api-ribbon可直接路由到http://localhost:8901/.

http://localhost:8904/api-feign/hello可路由到http://localhost:8902/hello

5. Zuul过滤器

zuul还提供了过滤功能，只要实现接口ZuulFilter即可对请求先进行筛选和过滤之后再路由到具体服务。

 package spring.helloworld.zuul.service;import javax.servlet.http.HttpServletRequest;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.stereotype.Component;import com.netflix.zuul.ZuulFilter;import com.netflix.zuul.context.RequestContext;@Componentpublic class DemoFilter extends ZuulFilter {private static Logger log = LoggerFactory.getLogger(DemoFilter.class);@Overridepublic String filterType() {return "pre";}@Overridepublic int filterOrder() {return 0;}@Overridepublic boolean shouldFilter() {return true;}@Overridepublic Object run() {RequestContext ctx = RequestContext.getCurrentContext();HttpServletRequest request = ctx.getRequest();String s = String.format("%s >>> %s", request.getMethod(), request.getRequestURL().toString());log.info(s);return null;}}

filterType：返回一个字符串代表过滤器的类型，在zuul中定义了四种不同生命周期的过滤器类型，具体如下：