SpringCloud微服务 之hystrix(三)

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/u012437781/article/details/83691907

前言

本小节我们学习一下如何是Feign拥有Hystrix的熔断功能。

案例

• Eureka Server端编写(参考前例)。
  

• Eureka Client端服务提供方编写。

  • 项目结构
    

  • CoreCode

    <?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>
    
    	<artifactId>microservice-deal-broker-cloud-hystrix-with-feign</artifactId>
    	<packaging>jar</packaging>
    
    	<name>microservice-deal-broker-cloud-hystrix-with-feign</name>
    	<description>Demo project for Spring Boot</description>
    
    	<parent>
    		<groupId>com.example</groupId>
    		<artifactId>microservice-deal-parent</artifactId>
    		<version>0.0.1-SNAPSHOT</version>
    	</parent>
    
    	<dependencies>
    		<!-- Eureka -->
    		<dependency>
    			<groupId>org.springframework.cloud</groupId>
    			<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    		</dependency>
    	
    		<!-- Feignf -->
    		<dependency>
    			<groupId>org.springframework.cloud</groupId>
    			<artifactId>spring-cloud-starter-openfeign</artifactId>
    		</dependency>
    		<!-- springCloud Hystrix依赖 -->
    		<dependency>
    			<groupId>org.springframework.cloud</groupId>
    			<artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
    		</dependency>
    
    	</dependencies>
    
    </project>
    
    

    @SpringBootApplication
    @EnableDiscoveryClient
    @EnableFeignClients //开启FeignClient注解
    @EnableCircuitBreaker //开启Hystrix熔断机制
    public class MicroserviceDealBrokerHystrixWithFeignApplication {
    
    	public static void main(String[] args) {
    		SpringApplication.run(MicroserviceDealBrokerHystrixWithFeignApplication.class,
    				args);
    	}
    }
    
    

    @FeignClient(name = "microservice-deal-cloud",fallback = HystrixFallBackMethod.class)
    public interface FeignConfig {
    
    	//第一个坑：使用Feign的时候,如果参数中带有@PathVariable形式的参数,则要用value=""标明对应的参数,否则会抛出IllegalStateException异常
    	@GetMapping("/deal/{id}")
    	public Deal findById(@PathVariable(value="id") Long id);
    }
    

    @Component
    public class HystrixFallBackMethod implements FeignConfig {
    
    	@Override
    	public Deal findById(Long id) {
    		Deal deal = new Deal();
    		deal.setId(id.intValue());
    		deal.setName("Dustyone");
    		return deal;
    	}
    
    }
    
    

    @RestController
    public class BrokerController {
    	
    	@Autowired
    	private FeignConfig feignConfig;
    	
    	@GetMapping("/deal/{id}")
    	public Deal findById(@PathVariable(value="id") Long id) {
    		return this.feignConfig.findById(id);
    	}
    }
    

• Eureka Client端服务提消费编写(单实例) (参考前例)。

• 访问：http://localhost:8082/deal/2
  

• 手动shutdown 服务提供者：
  

• 访问：http://localhost:8082/deal/2
  
  此时FeignClient中声明的 Hystrix熔断机制开启了。

小结

• 在FeignClient中声明Hystrix熔断机制需要在@FeignClient中声明fallback方法，同时配置文件中声明Feign对Hystrix的支持：feign:hystrix:enabled: true。
• 在主类中声明了@EnableFeignClients可以不需要对@EnableCircuitBreaker做声明(feign:hystrix:enabled: true一被声明)。
• 本小节使用的案例：microservice-deal-eureka、microservice-deal-cloud、microservice-deal-broker-cloud-hystrix-with-feign