Spring Cloud 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。

Spring Cloud 入门教程(九): 路由网关zuul

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.</modelVersion>
<groupId>cm.chry</groupId>
<artifactId>spring.helloworld.zuul.service</artifactId>
<version>0.0.-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..RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent> <properties>
<project.build.sourceEncoding>UTF-</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-</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>

pom.xml

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
@SpringBootApplication
public 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: 8904
spring:
application:
name: service-zuul
zuul:
routes:
ribbo:
path: /api-ribbon/**
serviceId: service-ribbon
feign:
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; @Component
public class DemoFilter extends ZuulFilter {
private static Logger log = LoggerFactory.getLogger(DemoFilter.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();
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:

  • 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

  • pre:路由之前
  • routing:路由之时
  • post: 路由之后
  • error:发送错误调用

shouldFilter:这里可以写逻辑判断,是否要过滤,本文true,永远过滤。

run:过滤器的具体逻辑,这里只是将请求的URL简单些到日志中

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