“Hello everyone! ”
路由网关（zuul）简介
路由网关（zuul）由来：
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/a转发到到a服务，/api/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。
zuul有以下功能：
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Authentication
Insights
Stress Testing
Canary Testing
Dynamic Routing
Service Migration
Load Shedding
Security
Static Response handling
Active/Active traffic management
第一步：创建条件
这一篇文章基于上一篇文章的工程.
第二步：创建service-zuul工程：
右键工程->创建创建module->选择spring initialir->web->web,cloud discovery->eureka discovery,cloud routing->zuul,然后一直下一步就行了。
创建完成后：
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<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.test</groupId>
<artifactId>service-zuul</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>service-zuul</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.RC2</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-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-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>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
</repository>
</repositories>
</project>
配置appication.yml文件：
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:
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server:
port: 9875
eureka:
client:
service-url:
defaultZone: http://localhost:9871/eureka/
spring:
application:
name: service-zuul
zuul:
routes:
api-a:
paht: /api-a/**
serviceId: service-ribbon
api-b:
path: /api-b/**
serviceId: service-feign
第三步 配置启动类
在工程的启动类中添加@EnableZuulProxy，开启zuul的功能：
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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);
}
}
第四步：启动所有工程
打开 http://localhost:9875/api-a/hello/?name=handsomeman ，你会在浏览器上看到显示：
hello handsomeman ,i am from port:9872
打开 http://localhost:9875/api-b/hello/?name=handsomeman ，浏览器会显示：
hello handsomeman ,i am from port:9872
第五步：实现服务过滤
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，代码如下：
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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;
@Component
public class AccessFilter extends ZuulFilter {
private static Logger logger = LoggerFactory.getLogger(AccessFilter.class);
// 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
@Override
public String filterType() {
// 1.pre:可以在请求被路由之前调用
// 2.routing:在请求时被调用
// 3.post:在routing和error过滤之后调用。
// 4.error：处理请求时发生错误是被调用。
return "pre";
}
// 过滤的顺序
@Override
public int filterOrder() {
return 0;
}
// 这里可以写逻辑判断，是否要过滤，本文true,永远过滤。
@Override
public boolean shouldFilter() {
return true;
}
// 过滤器的具体逻辑。可以很复杂，包括查sql，nosql去判断该请求到底有没有权限访问
@Override
public Object run() throws ZuulException {
RequestContext ctx = RequestContext.getCurrentContext();
HttpServletRequest request = ctx.getRequest();
logger.info(String.format("请求方式：%s -----请求url： %s", request.getMethod(), request.getRequestURL().toString()));
Object accessToken = request.getParameter("token");
if(accessToken == null) {
logger.warn("token is empty");
ctx.setSendZuulResponse(false);
ctx.setResponseStatusCode(401);
try {
ctx.getResponse().getWriter().write("token is empty");
}catch (Exception e){
}
return null;
}
logger.info("ok");
return null;
}
}
第六步：启动所有工程
打开 http://localhost:9875/api-a/hello/?name=handsomeman ，你会在浏览器上看到显示：
token is empty
打开 http://localhost:9875/api-a/hello/?token=123&name=handsomeman ，浏览器会显示：
hello handsomeman ,i am from port:9872
源码下载：
https://github.com/mochengyanliu/SpringCloudLearn/tree/master/section5
