SpringCloud-路由网关(Zuul)

在微服务架构中，需要几个基础的服务治理组件，包括服务注册与发现、服务消费、负载均衡、断路器、只能路由、配置管理等，由这几个基础组件相互协作，共同组建了一个简单的微服务系统。

在Spring Cloud微服务系统中，一种常见的负载均衡方式是，客户端的请求首先经过负载均衡(zuul、Nginx)，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，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。

Zuul简介

Zuul的只要功能是路由转发和过滤器。路由功能是微服务的一部分，比如/api/user转发到user服务，/api/shop转发到shop服务，zuul默认和Ribbon结合实现了负载均衡的功能。
Zuul有以下功能
• Authentication
• Insights
• Stress Testing
• Canary Testing
• Dynamic Routing
• Service Migration
• Load Shedding
• Security
• Static Response handling
• Active/Active traffic management

创建service-zuul工程

pom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>com.SpringCloud</groupId>
<artifactId>service-zuul</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
 
<name>service-zuul</name>
<description>service-zuul-description</description>
 
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.13.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>
<spring-cloud.version>Edgware.SR3</spring-cloud.version>
</properties>
 
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka-server</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>${spring-cloud.version}</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>
 
 
</project>

在程序入口application类加上注解@EnableZuulProxy,开启zuul的功能

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

application.yml如下

spring:
application:
name: service-zuul
server:
port: 8769
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
zuul:
routes:
api-a:
path: /api-a/**
serviceId: service-ribbon
api-b:
path: /api-b/**
serviceId: service-feign

以/api-a/开头的请求都转发给service-ribbon服务，以/api-b/开头的请求都转发给service-feign服务
启动eureka-server, eureka-client,service-ribbon,service-feign,service-zuul
请求http://localhost:8769/api-a/hi?name=fz

http://localhost:8769/api-b/hi?name=fz

这说明zuul起到了路由的作用

服务过滤

zuul不仅只是路由，并且还能过滤，做一些安全验证，如下

@Component
public class MyFilter extends ZuulFilter {
 
private static Logger log = LoggerFactory.getLogger(MyFilter.class);
 
@Override
public String filterType() {
return "pre";
}
 
@Override
public int filterOrder() {
return 0;
}
 
@Override
public boolean shouldFilter() {
return true;
}
 
@Override
public Object run() {
RequestContext ctx = RequestContext.getCurrentContext();
HttpServletRequest request = ctx.getRequest();
log.info(String.format("%s >>> %s", request.getMethod(), request.getRequestURL().toString()));
Object accessToken = request.getParameter("token");
if (accessToken == null) {
log.warn("token is empty");
ctx.setSendZuulResponse(false);
ctx.setResponseStatusCode(401);
try {
ctx.getResponse().getWriter().write("token is empty");
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
log.info("ok");
return null;
}
}

filterType:返回一个字符串代表过滤器的类型，在zuul中定义了四中不同生命周期的过滤器类型，具体如下：
pre : 路由之前
routing : 路由之时
post：路由之后
error：发送错误调用
filterOrder：过滤的顺序
shouldFilter:这里可以下逻辑判断，是否需要过滤，true，永远过滤
run:过滤器的具体逻辑。可用很复杂，包括查SQL，nosql去判断该请求到底有没有权限访问。

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