Spring Cloud 使用路由网关统一访问接口 Zuul

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

pom.xml

<?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>com.funtl</groupId>
        <artifactId>hello-spring-cloud-dependencies</artifactId>
        <version>1.0.0-SNAPSHOT</version>
        <relativePath>../hello-spring-cloud-dependencies/pom.xml</relativePath>
    </parent>
 
    <artifactId>hello-spring-cloud-zuul</artifactId>
    <packaging>jar</packaging>
 
    <name>hello-spring-cloud-zuul</name>
    <inceptionYear>2018-Now</inceptionYear>
 
    <dependencies>
        <!-- Spring Boot Begin -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- Spring Boot End -->
 
        <!-- Spring Cloud Begin -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-zuul</artifactId>
        </dependency>
        <!-- Spring Cloud End -->
    </dependencies>
 
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.lxq.hello.spring.cloud.zuul.ZuulApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

 启动类加上两个注解 

@EnableZuulProxy      //启动Zuul服务
@EnableEurekaClient  //启动eureka客户端(被eureka发现)

package com.lxq.hello.spring.cloud.zuul;

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;

/**
 * @Author Lxq
 * @Date 2020/3/29 14:42
 * @Version 1.0
 */
@EnableEurekaClient
@EnableZuulProxy
@SpringBootApplication
public class ZuulApplication {
    public static void main(String[] args) {
        SpringApplication.run(ZuulApplication.class, args);
    }
}

application.yml

spring:
  application:
    name: hello-spring-cloud-zuul
 
server:
  port: 8769    #zuul服务的端口
 
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/      #依然注册到eureka上
 
zuul:
  routes:   #路由
    api-a:  
      path: /api/a/**     #访问路径一  访问localhost:8769/api/a/hi是访问ribbon
      serviceId: hello-spring-cloud-web-admin-ribbon   #ribbon注册在eureka的服务名
    api-b: 
      path: /api/b/**     #访问路径二  访问localhost:8769/api/a/hi是访问feign
      serviceId: hello-spring-cloud-web-admin-feign    #feign注册在eureka的服务名

相当于zuul路由网关同一管理所有服务
访问 localhost:8769/api/a/hi   和   localhost:8769/api/b/hi  是否能正常访问说明Zuul配置成功

由于网路的不稳定性会出现网路震荡导致Zuul路由失败  如何解决   

 使用路由回调
 创建一个自定义回调类(名字随便但要有意义)  需要实现 spring cloud 提供的 FallBackProvider类

package com.lxq.hello.spring.cloud.zuul.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;

/**
 * @Author Lxq
 * @Date 2020/3/29 14:52
 * @Version 1.0
 * 路由回调
 */
@Component
public class WebAdminFeignFallbackProvider implements FallbackProvider {

    @Override
    public String getRoute() {
        // ServiceId，如果需要所有调用都支持回退，则 return "*" 或 return null
        return "hello-spring-cloud-web-admin-feign";

    }

    @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() {

            }

            /**
             *
             * @return 响应内容
             * @throws IOException
             */
            @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 headers = new HttpHeaders();
                // 和 getBody 中的内容编码一致
                headers.setContentType(MediaType.APPLICATION_JSON_UTF8);
                return headers;
            }
        };


    }
}

 zuul 还可以有过滤的功能，模拟登陆过滤

package com.lxq.hello.spring.cloud.zuul.filter;

import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
import com.netflix.zuul.exception.ZuulException;
import org.springframework.stereotype.Component;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @Author Lxq
 * @Date 2020/3/29 15:01
 * @Version 1.0
 */
@Component
public class LoginFilter extends ZuulFilter {

    @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 currentContext = RequestContext.getCurrentContext();
        HttpServletRequest request = currentContext.getRequest();
        String token = request.getParameter("token");
        if (token == null){
            currentContext.setSendZuulResponse(false);
            currentContext.setResponseStatusCode(401);
            HttpServletResponse response = currentContext.getResponse();
            response.setContentType("text/html;charset=utf-8");
            try {
                response.getWriter().write("非法请求");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }
}