微服务网关Zuul

一、Zuul简介

Zuul是Netflix开源的微服务网关，包含对请求的路由和过滤两个主要功能。

1）路由功能：负责将外部请求转发到具体的微服务实例上，是实现外部访问统一入口的基础。

2）过滤功能：负责对请求的过程进行干预，可以实现请求校验、服务聚合等功能。

二、Zuul代码实现

1）在pom.xml中引入依赖

注意：系统中所有的微服务须连接至Eureka注册中心。Eureka搭建详见另一篇博文：微服务1：搭建微服务注册中心Eureka（命令行简易版，不使用IDE）-CSDN博客

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

完整的pom.xml如下：

<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  
  <groupId>com.test</groupId>
  <artifactId>microservice-zuul</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>microservice-zuul</name>
  <url>http://maven.apache.org</url>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.3.0.RELEASE</version>
    <relativePath/> 
  </parent>
    
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
  	<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>   
    
    <dependency>
 				<groupId>org.springframework.cloud</groupId>
 				<artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
 		</dependency> 
 		
 		<dependency>
 				<groupId>org.springframework.cloud</groupId>
 				<artifactId>spring-cloud-starter-netflix-zuul</artifactId>
 		</dependency>
    
  </dependencies>
  
  
      <dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Hoxton.SR4</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>

2）配置application.yml

server:
  port: 9000
spring:
  application:
    name: microservice-zuul

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8080/eureka/

3）在App.java中添加注解

@EnableDiscoveryClient
@EnableZuulProxy

package com.test;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
import org.springframework.cloud.netflix.zuul.EnableZuulProxy;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

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

}

三、Zuul测试

在浏览器中输入：

http://localhost:9000/microservice-consumer/users/4

其中microservice-consumer是实际要访问的微服务名称，如果不加Zuul，则该服务的访问URL为：

http://localhost:8010/users/3

使用Zuul网关之后，客户端无需知道每个微服务的端口号，即可通过网关端口号9000来统一访问到系统中所有的微服务。