Feign使用Hystrix实现断路器简单案例
断路器的作用是为了保护系统，控制故障范围不再扩大
为了保证系统的高可用，一般我们都会将单个服务进行集群部署，由于网络原因或者其他原因导致单个服务出现问题，调用这个服务时就会线程阻塞，若此时有大量请求涌入，Servlet容器线程资源被消耗完毕，就会导致服务瘫痪。服务与服务之间存在依赖性，故障会传播，会对整个服务器系统造成灾难性的严重后果，这就是服务故障的雪崩效应。
Feign中已经集成了Hystrix，所以我们使用Feign中的Hystrix就可以了。
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首先创建spring cloud 项目
引入pom
<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>4.0.0modelVersion> <groupId>com.hystrixgroupId> <artifactId>exam-hystrix-demoartifactId> <packaging>pompackaging> <version>1.0-SNAPSHOTversion> <modules> <module>exam-hystrix-eureka-servermodule> <module>exam-hystrix-servermodule> <module>exam-hystrix-clientmodule> modules> <parent> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-parentartifactId> <version>2.0.3.RELEASEversion> parent> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-dependenciesartifactId> <version>Finchley.SR2version> <scope>importscope> <type>pomtype> dependency> dependencies> dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-webartifactId> dependency> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-testartifactId> dependency> dependencies> project> -
我们需要创建一个注册中心，我们用Eureka
引入pom
<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"> <parent> <artifactId>exam-hystrix-demoartifactId> <groupId>com.hystrixgroupId> <version>1.0-SNAPSHOTversion> parent> <modelVersion>4.0.0modelVersion> <artifactId>exam-hystrix-eureka-serverartifactId> <dependencies> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-netflix-eureka-serverartifactId> dependency> dependencies> project>创建配置文件
#服务的端口号 server.port=8080 #服务的名字 spring.application.name=TEST-EUREKA-SERVER #配置数据复制的peer节点 eureka.client.service-url.defaultZone= http://localhost:8080/eureka #关闭自我保护 eureka.server.enable-self-preservation=false #不注册自己到Eureka注册中心 eureka.client.register-with-eureka=false #配置不获取注册信息 eureka.client.fetch-registry=false启动类
package com.hystrix; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer; /** * @ClassName EurekaServerApplication * @Description: 注册中心启动类 * @Author 小松 * @Date 2019/7/11 **/ @SpringBootApplication @EnableEurekaServer public class EurekaServerApplication { public static void main(String[] args) { SpringApplication.run(EurekaServerApplication.class,args); } } -
创建服务端服务，为了简单我们只创建一个服务
引入pom
<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"> <parent> <artifactId>exam-hystrix-demoartifactId> <groupId>com.hystrixgroupId> <version>1.0-SNAPSHOTversion> parent> <modelVersion>4.0.0modelVersion> <artifactId>exam-hystrix-serverartifactId> <dependencies> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId> dependency> dependencies> project>配置文件
#服务端口 server.port=8081 #服务名称 spring.application.name=SERVER #注册中心地址 eureka.client.service-url.defaultZone= http://localhost:8080/eureka启动类
package com.hystrix; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.EnableEurekaClient; /** * @ClassName HystrixServerApplication * @Description: 服务启动类 * @Author 小松 * @Date 2019/7/11 **/ @SpringBootApplication @EnableEurekaClient public class HystrixServerApplication { public static void main(String[] args) { SpringApplication.run(HystrixServerApplication.class,args); } }创建一个控制层接口，供客户端调用
package com.hystrix.web; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; /** * @ClassName HystrixServerController * @Description: 服务接口 * @Author 小松 * @Date 2019/7/11 **/ @RestController public class HystrixServerController { //被调用的服务接口 @RequestMapping("testServer") public String testServer() throws InterruptedException { // Thread.sleep(4000); 测试超时保护用 return "服务正常"; } } -
创建客户端
引入pom
<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"> <parent> <artifactId>exam-hystrix-demoartifactId> <groupId>com.hystrixgroupId> <version>1.0-SNAPSHOTversion> parent> <modelVersion>4.0.0modelVersion> <artifactId>exam-hystrix-clientartifactId> <dependencies> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId> dependency> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-netflix-ribbonartifactId> dependency> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-openfeignartifactId> dependency> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-netflix-hystrixartifactId> <version>2.0.3.RELEASEversion> dependency> dependencies> project>配置文件
#服务端口号 server.port=8085 #服务名称 spring.application.name=client #注册中心地址 eureka.client.service-url.defaultZone= http://localhost:8080/eureka #开启hystrix feign.hystrix.enabled=true #配置ribbon的连接超时时间，因为feign默认调用ribbon实现负载均衡的，所以需要配置 #ribbon.ReadTimeout=5000 #ribbon.ConnectTimeout=5000 #开启hystrix连接超时配置 #hystrix.command.default.execution.timeout.enabled=true #连接超过10秒后,启用hystrix进行容错 #hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds=5000启动类
package com.hystrix; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker; import org.springframework.cloud.openfeign.EnableFeignClients; /** * @ClassName HystrixClientApplication * @Description: 客户端启动类 * @Author 小松 * @Date 2019/7/11 **/ @SpringBootApplication @EnableCircuitBreaker @EnableFeignClients public class HystrixClientApplication { public static void main(String[] args) { SpringApplication.run(HystrixClientApplication.class,args); } }feign调用服务接口
package com.hystrix.web; import org.springframework.cloud.openfeign.FeignClient; import org.springframework.stereotype.Component; import org.springframework.web.bind.annotation.RequestMapping; @Component @FeignClient(name = "SERVER",fallback = HystrixInterfaceImpl.class) public interface HystrixInterface { /** * 通过feign调用服务中的请求 * 当服务不可用或超时等异常则进入HystrixInterfaceImpl * @return */ @RequestMapping("testServer") public String testClient(); }容错实现类
package com.hystrix.web; import org.springframework.stereotype.Component; /** * @ClassName HystrixInterfaceImpl * @Description: 容错 * @Author 小松 * @Date 2019/7/11 **/ @Component public class HystrixInterfaceImpl implements HystrixInterface { @Override public String testClient() { System.out.println("=======容错====="); return "容错"; } }客户端控制层接口
package com.hystrix.web; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; /** * @ClassName HystrixController * @Description: 客户端控制层 * @Author 小松 * @Date 2019/7/11 **/ @RestController public class HystrixController { @Autowired HystrixInterface hystrixInterface; @RequestMapping("test") public String testClient() { String s = hystrixInterface.testClient(); return s; } } -
到此创建完毕
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启动注册中心服务，启动服务，启动客户端服务
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我们在浏览器地址中输入
http://localhost:8085/test可以正常访问到服务 -
我们模拟服务不可用的状态，将服务端停掉，再次访问
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可以看到，经过hytrix进入了容错
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ok，到此就结束了一个非常间的小案例，敏感的同学可以发现，我注释掉一个超时的代码和配置，有兴趣的话可以研究一下，超时进入容错
此项目已上传至GitHub：https://github.com/Jason-ljs/exam-hystrix-demo