Spring Cloud基础教程（七）：路由网关使用（Zuul）

本文主要是介绍Spring Cloud基础教程（七）：路由网关使用（Zuul），希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

一、概述

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/client-a/转发到到a服务，/client-b/转发到到b服务。zuul默认和Ribbon结合实现了负载均衡的功能。

二、准备

将服务注册与发现这篇博客中的Eureka-Client-A工程，复制一份，名字修改为Service-Zuul。

三、工程修改

Gradle依赖修改为

dependencies {compile('org.springframework.cloud:spring-cloud-starter-netflix-eureka-client')compile('org.springframework.cloud:spring-cloud-starter-zuul:1.4.4.RELEASE')compile('org.springframework.boot:spring-boot-starter-web')testCompile('org.springframework.boot:spring-boot-starter-test')
}

在启动类上添加@EnableZuulProxy注解，开启路由功能。

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

修改application.properties配置文件，将/client-a/开头的请求路由到eureka-client-a服务器

spring.application.name=service-zuul
server.port=10010
eureka.client.serviceUrl.defaultZone=http://localhost:10001/eureka/zuul.routes.api-a.path: /client-a/**
zuul.routes.api-a.serviceId: eureka-client-a

四、测试

启动之前的Eureka-Server、Eureka-Client-A和当前的Service-Zuul工程，访问http://127.0.0.1:10001/

发现都已经注册到了注册中心，访问http://127.0.0.1:10010/client-a/client，会发现路由到了Eureka-Client-A

五、服务过滤

Zuul不仅有路由的功能，还有服务过滤的功能，做一些拦截验证。

新建MyFilter类

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;/*** Created by wzj on 2018/5/24.*/
@Component
public class MyFilter extends ZuulFilter
{private static Logger log = LoggerFactory.getLogger(MyFilter.class);/*** to classify a filter by type. Standard types in Zuul are "pre" for pre-routing filtering,* "route" for routing to an origin, "post" for post-routing filters, "error" for error handling.* We also support a "static" type for static responses see  StaticResponseFilter.* Any filterType made be created or added and run by calling FilterProcessor.runFilters(type)** @return A String representing that type*/@Overridepublic String filterType(){return "pre";}/*** filterOrder() must also be defined for a filter. Filters may have the same  filterOrder if precedence is not* important for a filter. filterOrders do not need to be sequential.** @return the int order of a filter*/@Overridepublic int filterOrder(){return 0;}/*** a "true" return from this method means that the run() method should be invoked** @return true if the run() method should be invoked. false will not invoke the run() method*/@Overridepublic boolean shouldFilter(){return true;}/*** if shouldFilter() is true, this method will be invoked. this method is the core method of a ZuulFilter** @return Some arbitrary artifact may be returned. Current implementation ignores it.* @throws ZuulException if an error occurs during execution.*/@Overridepublic Object run() throws ZuulException{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){}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中定义了四种不同生命周期的过滤器类型，具体如下：