[023-01-40].第40节：组件应用 - OpenFeign与 Sentinel 集成实现fallback服务降级

SpringCloud学习大纲

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一、需求说明：

需求1：通过fallback属性进行统一配置

a.问题分析：

• 1.需要实现cloudalibaba-consumer-nacos-order83模块通过OpenFeign调用cloudalibaba-provider-payment9001
  • 83服务通过OpenFeign调用 9001微服务，正常访问OK
  • 83服务通过OpenFeign调用 9001微服务，异常访问error
• 2.访问者要有fallback服务降级的情况，不要持续访问9001加大微服务负担，但是通过feign接口调用的各个方法又自不同，如果每个不同方法都加一个fallback配对方法，会导致代码膨胀不好管理，工程埋雷…
  

b.解决办法：

• 在feign接口里面定义的全部方法都走统一的服务降级，一个搞定即可
  

需求2：Sentinel访问触发了自定义的限流配置

• 9001微服务自身还带着sentinel内部配置的流控规则，如果满足也会被触发
• Sentinel访问触发了自定义的限流配置,在注解@SentinelResource里面配置的blockHandler方法

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二、案例实现：

2.1.启动nacos和Sentinue

• 启动nacos: startup.cmd -m standalone
• 启动Sentine: java -jar sentinel-dashboard-1.8.6.jar

2.2.修改服务启动方法：cloudalibaba-provider-payment9001

改pom

<?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.atguigu.cloud</groupId><artifactId>mscloudV5</artifactId><version>1.0-SNAPSHOT</version></parent><artifactId>cloudalibaba-provider-payment9001</artifactId><properties><maven.compiler.source>17</maven.compiler.source><maven.compiler.target>17</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><!--openfeign--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><!--alibaba-sentinel--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId></dependency><!--nacos-discovery--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!-- 引入自己定义的api通用包 --><dependency><groupId>com.atguigu.cloud</groupId><artifactId>cloud-api-commons</artifactId><version>1.0-SNAPSHOT</version></dependency><!--SpringBoot通用依赖模块--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><!--hutool--><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId></dependency><!--lombok--><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.28</version><scope>provided</scope></dependency><!--test--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

写yml

server:port: 9001spring:application:name: nacos-payment-providercloud:nacos:discovery:server-addr: localhost:8848 #配置Nacos地址sentinel:transport:dashboard: localhost:8080 #配置Sentinel dashboard控制台服务地址port: 8719 #默认8719端口，假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口

主启动：

package com.atguigu.cloud;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
@SpringBootApplication
@EnableDiscoveryClient
public class Main9001{public static void main(String[] args){SpringApplication.run(Main9001.class,args);}
}

业务类：

package com.atguigu.cloud.controller;import cn.hutool.core.util.IdUtil;
import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.atguigu.cloud.entities.PayDTO;
import com.atguigu.cloud.resp.ResultData;
import com.atguigu.cloud.resp.ReturnCodeEnum;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;import java.math.BigDecimal;@RestController
public class PayAlibabaController{@Value("${server.port}")private String serverPort;@GetMapping(value = "/pay/nacos/{id}")public String getPayInfo(@PathVariable("id") Integer id){return "nacos registry, serverPort: "+ serverPort+"\t id"+id;}@GetMapping("/pay/nacos/get/{orderNo}")@SentinelResource(value = "getPayByOrderNo",blockHandler = "handlerBlockHandler")public ResultData getPayByOrderNo(@PathVariable("orderNo") String orderNo){//模拟从数据库查询出数据并赋值给DTOPayDTO payDTO = new PayDTO();payDTO.setId(1024);payDTO.setOrderNo(orderNo);payDTO.setAmount(BigDecimal.valueOf(9.9));payDTO.setPayNo("pay:"+IdUtil.fastUUID());payDTO.setUserId(1);return ResultData.success("查询返回值："+payDTO);}public ResultData handlerBlockHandler(@PathVariable("orderNo") String orderNo,BlockException exception){return ResultData.fail(ReturnCodeEnum.RC500.getCode(),"getPayByOrderNo服务不可用，" +"触发sentinel流控配置规则"+"\t"+"o(╥﹏╥)o");}/*fallback服务降级方法纳入到Feign接口统一处理，全局一个public ResultData myFallBack(@PathVariable("orderNo") String orderNo,Throwable throwable){return ResultData.fail(ReturnCodeEnum.RC500.getCode(),"异常情况："+throwable.getMessage());}*/
}

启动9001微服务：

2.3.修改cloud-api-commons

改pom

<?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.atguigu.cloud</groupId><artifactId>cloud2024</artifactId><version>1.0-SNAPSHOT</version></parent><artifactId>cloud-api-commons</artifactId><properties><maven.compiler.source>17</maven.compiler.source><maven.compiler.target>17</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><!--openfeign--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><!--alibaba-sentinel--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId></dependency><!--web + actuator--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><!--hutool--><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

新增PayFeignSentinelApi接口：

package com.atguigu.cloud.apis;
import com.atguigu.cloud.resp.ResultData;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
@FeignClient(value = "nacos-payment-provider",fallback = PayFeignSentinelApiFallBack.class)
public interface PayFeignSentinelApi{@GetMapping("/pay/nacos/get/{orderNo}")public ResultData getPayByOrderNo(@PathVariable("orderNo") String orderNo);
}

为远程调用新建全局统一服务降级类：

package com.atguigu.cloud.apis;import com.atguigu.cloud.resp.ResultData;
import com.atguigu.cloud.resp.ReturnCodeEnum;
import org.springframework.stereotype.Component;@Component
public class PayFeignSentinelApiFallBack implements PayFeignSentinelApi{@Overridepublic ResultData getPayByOrderNo(String orderNo){return ResultData.fail(ReturnCodeEnum.RC500.getCode(),"对方服务宕机或不可用，FallBack服务降级o(╥﹏╥)o");}
}

业务类：

<!-- 引入自己定义的api通用包 -->
<dependency><groupId>com.atguigu.cloud</groupId><artifactId>cloud-api-commons</artifactId><version>1.0-SNAPSHOT</version>
</dependency>

2.4.修改cloudalibaba-consumer-nacos-order83

改pom

<?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.atguigu.cloud</groupId><artifactId>mscloudV5</artifactId><version>1.0-SNAPSHOT</version></parent><artifactId>cloudalibaba-consumer-nacos-order83</artifactId><properties><maven.compiler.source>17</maven.compiler.source><maven.compiler.target>17</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><!-- 引入自己定义的api通用包 --><dependency><groupId>com.atguigu.cloud</groupId><artifactId>cloud-api-commons</artifactId><version>1.0-SNAPSHOT</version></dependency><!--openfeign--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><!--alibaba-sentinel--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId></dependency><!--nacos-discovery--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!--loadbalancer--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-loadbalancer</artifactId></dependency><!--web + actuator--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><!--lombok--><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build>
</project>

写yml

server:port: 83spring:application:name: nacos-order-consumercloud:nacos:discovery:server-addr: localhost:8848
#消费者将要去访问的微服务名称(nacos微服务提供者叫什么你写什么)
service-url:nacos-user-service: http://nacos-payment-provider# 激活Sentinel对Feign的支持
feign:sentinel:enabled: true

主启动：

package com.atguigu.cloud;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;@EnableDiscoveryClient
@SpringBootApplication
@EnableFeignClients
public class Main83{public static void main(String[] args){SpringApplication.run(Main83.class,args);}
}

业务类：

package com.atguigu.cloud.controller;
import com.atguigu.cloud.apis.PayFeignSentinelApi;
import com.atguigu.cloud.resp.ResultData;
import jakarta.annotation.Resource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
@RestController
public class OrderNacosController{@Resourceprivate RestTemplate restTemplate;@Resourceprivate PayFeignSentinelApi payFeignSentinelApi;@Value("${service-url.nacos-user-service}")private String serverURL;@GetMapping("/consumer/pay/nacos/{id}")public String paymentInfo(@PathVariable("id") Integer id){String result = restTemplate.getForObject(serverURL + "/pay/nacos/" + id, String.class);return result+"\t"+"    我是OrderNacosController83调用者。。。。。。";}@GetMapping(value = "/consumer/pay/nacos/get/{orderNo}")public ResultData getPayByOrderNo(@PathVariable("orderNo") String orderNo){return payFeignSentinelApi.getPayByOrderNo(orderNo);}
}

启动83服务

2.5.测试验证：

• 9001正常启动后，再启动83，通过feign调用
• 测试地址：
  
• 3.sentinue流控为例，进行配置：测试发现频繁访问触发了Sentinue的流控规则，blockHandler起效
  
• 4.9001宕机了，83通过feign调用，降级效果如下图