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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
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Eureka Server端编写(参考前例)。
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Eureka Client端服务提供方编写。
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项目结构
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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); } }
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Eureka Client端服务提消费编写(单实例) (参考前例)。
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手动shutdown 服务提供者:
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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