场景
SpringCloud-服务注册与实现-Eureka创建服务注册中心(附源码下载):
https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102535957
SpringCloud-服务注册与实现-Eureka创建服务提供者(附源码下载):
https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102558004
SpringCloud-创建服务消费者-Ribbon方式(附代码下载):
https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102558080
SpringCloud-创建服务消费者-Feign方式(附代码下载)::
https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102595895
在上面已经实现服务注册中心、服务提供者和以Ribbon方式和Fign方式实现服务消费者的前提下,使用熔断器防止服务雪崩。
在微服务架构中,根据业务来拆分成一个个的服务,服务与服务之间可以通过 RPC 相互调用,在 Spring Cloud 中可以用 RestTemplate + Ribbon 和 Feign 来调用。为了保证其高可用,单个服务通常会集群部署。由于网络原因或者自身的原因,服务并不能保证 100% 可用,如果单个服务出现问题,调用这个服务就会出现线程阻塞,此时若有大量的请求涌入,Servlet 容器的线程资源会被消耗完毕,导致服务瘫痪。服务与服务之间的依赖性,故障会传播,会对整个微服务系统造成灾难性的严重后果,这就是服务故障的 “雪崩” 效应。
熔断器打开后,为了避免连锁故障,通过 fallback 方法可以直接返回一个固定值。
注:
博客:
https://blog.csdn.net/badao_liumang_qizhi
关注公众号
霸道的程序猿
获取编程相关电子书、教程推送与免费下载。
实现
Ribbon中使用熔断器
SpringCloud-创建服务消费者-Ribbon方式(附代码下载):
https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102558080
在上面使用Ribbon实现创建服务消费者。
我们在pom.xml中加入hystrix的依赖:
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-hystrix</artifactId> </dependency>
完整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.badao</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-web-admin-ribbon</artifactId> <packaging>jar</packaging> <name>hello-spring-cloud-web-admin-ribbon</name> <url>https://blog.csdn.net/badao_liumang_qizhi</url> <inceptionYear>2019-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-thymeleaf</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-ribbon</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-hystrix</artifactId> </dependency> <!-- Spring Cloud End --> <!-- 解决 thymeleaf 模板引擎一定要执行严格的 html5 格式校验问题 --> <dependency> <groupId>net.sourceforge.nekohtml</groupId> <artifactId>nekohtml</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <mainClass>com.funtl.hello.spring.cloud.web.admin.ribbon.WebAdminRibbonApplication</mainClass> </configuration> </plugin> </plugins> </build> </project>
然后在应用启动类Application中增加@EnableHystrix注解
package com.badao.hello.spring.cloud.web.admin.ribbon; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.discovery.EnableDiscoveryClient; @SpringBootApplication @EnableDiscoveryClient @EnableHystrix public class WebAdminRibbonApplication { public static void main(String[] args) { SpringApplication.run(WebAdminRibbonApplication.class, args); } }
然后在Service中添加@HystrixCommand注解
在 Ribbon 调用方法上增加 @HystrixCommand 注解并指定 fallbackMethod 熔断方法。
package com.badao.hello.spring.cloud.web.admin.ribbon.service; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import org.springframework.web.client.RestTemplate; @Service public class AdminService { @Autowired private RestTemplate restTemplate; @HystrixCommand(fallbackMethod = "hiError") public String sayHi(String message) { return restTemplate.getForObject("http://hello-spring-cloud-service-admin/hi?message=" + message, String.class); } public String hiError(String message) { return "Hi,your message is :"" + message + "" but request error."; } }
测试熔断器
为了测试熔断器效果,我们将服务提供者关闭,此时再次请求:
http://localhost:8764/hi?message=HelloRibbon
Feign中使用熔断器
Feign自带熔断器,所以不用添加依赖,只需要在配置文件中配置打开。
feign: hystrix: enabled: true
完整配置文件:
spring: application: name: hello-spring-cloud-web-admin-feign thymeleaf: cache: false mode: LEGACYHTML5 encoding: UTF-8 servlet: content-type: text/html server: port: 8765 eureka: client: serviceUrl: defaultZone: http://localhost:8761/eureka/ feign: hystrix: enabled: true
然后再Service中增加fallback指定类
package com.badao.hello.spring.cloud.web.feign.service; import org.springframework.cloud.openfeign.FeignClient; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RequestParam; @FeignClient(value = "hello-spring-cloud-service-admin", fallback = AdminServiceHystrix.class) public interface AdminService { @RequestMapping(value = "hi", method = RequestMethod.GET) public String sayHi(@RequestParam(value = "message") String message); }
此时再service包下创建熔断器并实现对应的Feign接口
package com.badao.hello.spring.cloud.web.feign.service; import org.springframework.stereotype.Component; @Component public class AdminServiceHystrix implements AdminService { @Override public String sayHi(String message) { return "Hi,your message is :"" + message + "" but request error."; } }
然后将服务提供者关闭,再次请求:
http://localhost:8765/hi?message=HelloFeign
代码下载
https://download.csdn.net/download/badao_liumang_qizhi/11871136