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  • SpringCloud教程第5篇:Zuul(F版本)

    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、智能路由、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。一个简答的微服务系统如下图:

    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、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。

    一、Zuul简介

    Zuul的主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转发到到user服务,/api/shop转发到到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

    二、准备工作

    继续使用上一节的工程。在原有的工程上,创建一个新的工程。

    三、创建service-zuul工程

    其pom.xml文件如下:

    <?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.forezp</groupId>
        <artifactId>service-zuul</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>service-zuul</name>
        <description>Demo project for Spring Boot</description>
    
        <parent>
            <groupId>com.forezp</groupId>
            <artifactId>sc-f-chapter5</artifactId>
            <version>1.0-SNAPSHOT</version>
        </parent>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</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-netflix-zuul</artifactId>
            </dependency>
        </dependencies>
    
    </project>

    在其入口applicaton类加上注解@EnableZuulProxy,开启zuul的功能:

    package com.forezp.servicezuul;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.cloud.netflix.zuul.EnableZuulProxy;
    
    @SpringBootApplication
    @EnableEurekaClient
    @EnableDiscoveryClient
    @EnableZuulProxy
    public class ServiceZuulApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(ServiceZuulApplication.class, args);
        }
    
    }

    加上配置文件application.yml加上以下的配置代码:

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

    依次启动eureka-server、 eureka-hi 、 service-ribbon、 service-feign、service-zuul这五个服务

    打开浏览器访问:http://localhost:8769/api-a/hi?name=forezp ;浏览器显示:

    打开浏览器访问:http://localhost:8769/api-b/hello?name=forezp ;浏览器显示:

    这说明zuul起到了路由的作用

    四、服务过滤

    zuul不仅只是路由,并且还能过滤,做一些安全验证。继续改造工程;

    package com.forezp.servicezuul.filter;
    
    import com.netflix.zuul.ZuulFilter;
    import com.netflix.zuul.context.RequestContext;
    import com.netflix.zuul.exception.ZuulException;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.stereotype.Component;
    
    import javax.servlet.http.HttpServletRequest;
    import java.io.IOException;
    
    /**
     * @Auther: chengmr
     * @Date: 2020/6/23 16:21
     * @Description:
     */
    @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() throws ZuulException {
            RequestContext ctx = RequestContext.getCurrentContext();
            HttpServletRequest request = ctx.getRequest();
            log.info(String.format("%s >>> %s",request.getMethod(),request.getRequestURL().toString()));
            Object token = request.getParameter("token");
            if(token==null){
                log.warn("token is empty");
                ctx.setSendZuulResponse(false);
                ctx.setResponseStatusCode(401);
                try {
                    ctx.getResponse().getWriter().write("token is empty");
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            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
    • 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。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。

    这时访问:http://localhost:8769/api-a/hi?name=forezp ;网页显示:

    访问 http://localhost:8769/api-a/hi?name=forezp&token=22 ; 网页显示:

    源码:https://github.com/CMRcircle/learnspringcloud/tree/master/sc-f-chapter5

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  • 原文地址:https://www.cnblogs.com/chengmr/p/13182885.html
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