SpringCloud架构--Zuul路由转发过滤(第五篇)

参考：https://blog.csdn.net/forezp/article/details/81041012

Zuul

Zuul主要是路由转发和过滤。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，转发到具体的服务后，再根据ribbon或者feign访问多实例中具体的某一个节点，实现负载均衡负载，zuul默认和Ribbon结合实现了负载均衡的功能。

实践

前期工作，建立在前面项目的基础上

创建zuul-serveice工程，导入依赖包：

<?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>

    <groupId>com.example</groupId>
    <artifactId>servicezuul</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>servicezuul</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR1</spring-cloud.version>
    </properties>

    <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>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </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>
</project>

配置application.yml，将项目注册的eureka中，其中以/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；

eureka:
    client:
        serviceUrl:
            defaultZone: http://localhost:8761/eureka/
server:
    port: 8080
spring:
    application:
        name: service-zuul
zuul:
    routes:
        api-a:
            path: /api-a/**
            serviceId: service-ribbon
        api-b:
            path: /api-b/**
            serviceId: service-feign

启动类增加zuul，eurekaClient注解：

1 2	`@EnableZuulProxy @EnableEurekaClient`

启动如下几个程序

5、访问
http://localhost:8080/api-a/sayHi?name=张三
或者
http://localhost:8080/api-b/sayHi?name=张三

可以开启Debug模式，查看服务所调用的模块。

zuul还有其他额外功能，如安全验证、过滤等

新建一个Filter类：

package com.example.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;

@Component
public class FilterTest extends ZuulFilter {


    private Logger logger = LoggerFactory.getLogger(FilterTest.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();
        logger.info(request.getMethod()+" >>> "+request.getRequestURL().toString());
        Object accessToken = request.getParameter("token");
        if (accessToken == null) {
            logger.warn("token is null!!!");
            ctx.setSendZuulResponse(false);
            ctx.setResponseStatusCode(401);
            try {
                ctx.getResponse().getWriter().write("token is null!!!");
            } catch (Exception e) {
                e.printStackTrace();
            }

            return null;
        }
        logger.info("token is ok!!!");
        return null;
    }
}

其中：
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
pre：路由前
routing：路由时
post：路由后
error：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
run：过滤器的具体逻辑

访问：http://localhost:8080/api-a/sayHi?name=张三

后台日志：