SpringCloud-使用Zuul路由网关统一访问接口

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、熔断器、智能路由、配置管理等等。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。

一个简单的微服务系统如下:

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、Nginx),在到达服务网关(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，服务的所有配置文件由配置服务管理，配置服务的配置文件放到Git仓库，方便开发人员随时更改配置。

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User服务,/api/shop转发到Shop服务。Zull默认和Ribbon结合实现了负载均衡功能。

创建路由网关

pom.xml配置如下

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.springcloud.bh</groupId>
    <artifactId>zuul</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>zuul</name>
    <description>统一路由网关Zuul</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.RELEASE</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>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</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>

主要是增加了Zuul的依赖

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

Application

增加@EnableZuulProxy注解，开启Zuul功能

package com.springcloud.bh;

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
@EnableZuulProxy
@EnableEurekaClient
public class ZuulApplication {

    public static void main(String[] args) {
        SpringApplication.run(ZuulApplication.class, args);
    }
}

application.yml

设置端口号为：8766
增加Zuul配置 ```yaml server: port: 8766

spring: application: name: zuul

eureka: client: service-url: defaultZone: http://localhost:8761/eureka/

zuul: routes: api-a: path: /api/a/** serviceId: eureka-consumer-ribbon api-b: path: /api/b/** serviceId: eureka-consumer-feign

路由说明:
*   以`/api/a`开头的请求都转发给`eureka-consumer-ribbon`服务
*   以`/api/b`开头的请求都转发给`eureka-consumer-feign`服务

##  测试访问
打开浏览器访问：http://localhost:8766:/api/a/hi?message=hi,Ribbon 浏览器显示

>   你的消息是：hi,Ribbon 端口号：8763

打开浏览器访问：http://localhost:8766:/api/b/hi?message=hi,Feign 浏览器显示

>   你的消息是：hi,Feign 端口号：8763

至此说明Zuul的路由功能配置成功。

##  配置网关路由失败时的回调
```java
package com.springcloud.bh.provider;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.cloud.netflix.zuul.filters.route.FallbackProvider;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.stereotype.Component;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;


@Component
public class AdminFeignFallbackProvider implements FallbackProvider {
    @Override
    public String getRoute() {
        return "eureka-consumer-feign";
    }

    /**
     * 如果请求服务失败，则返回指定信息给调用者
     * @param route
     * @param cause
     * @return
     */
    @Override
    public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
        return new ClientHttpResponse() {
            /**
             * 网关向Api服务请求失败了，但是消费者客户端向网关发起的请求是成功的，
             * 不应该把Api的404,500等问题抛给客户端
             * 网关和Api服务集群对于客户端来说是黑盒
             * @return
             * @throws IOException
             */
            @Override
            public HttpStatus getStatusCode() throws IOException {
                return HttpStatus.OK;
            }

            @Override
            public int getRawStatusCode() throws IOException {
                return HttpStatus.OK.value();
            }

            @Override
            public String getStatusText() throws IOException {
                return HttpStatus.OK.getReasonPhrase();
            }

            @Override
            public void close() {

            }

            @Override
            public InputStream getBody() throws IOException {
                ObjectMapper objectMapper=new ObjectMapper();
                Map<String,Object> map=new HashMap<>();
                map.put("status",200);
                map.put("message","无法连接，请检查您的网络");
                return new ByteArrayInputStream(objectMapper.writeValueAsString(map).getBytes("UTF-8"));
            }

            @Override
            public HttpHeaders getHeaders() {
                HttpHeaders httpHeaders=new HttpHeaders();
                httpHeaders.setContentType(MediaType.APPLICATION_JSON_UTF8);
                return null;
            }
        };
    }
}

当网关路由失败时，则自动执行此回调。

源码地址

Github: https://github.com/yeshang5/springcloud-example