SpringCloud-使用熔断器防止服务雪崩-Ribbon和Feign方式(附代码下载)

拼搏现实的明天。 2023-10-11 13:49 46阅读 0赞

## 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][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][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][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][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。

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## 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][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>
            
            <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>
            
    
            
            <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>
            
    
            
            <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][http_localhost_8764_hi_message_HelloRibbon]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70][]

### 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

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1][]

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][http_localhost_8765_hi_message_HelloFeign]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2][]

### 代码下载 ###

[https://download.csdn.net/download/badao\_liumang\_qizhi/11871136][https_download.csdn.net_download_badao_liumang_qizhi_11871136]

###     ###

[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_102535957]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102535957
[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_102558004]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102558004
[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_102558080]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102558080
[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_102595895]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102595895
[https_blog.csdn.net_badao_liumang_qizhi]: https://blog.csdn.net/badao_liumang_qizhi
[http_localhost_8764_hi_message_HelloRibbon]: http://localhost:8764/hi?message=HelloRibbon
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/2019101723000565.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20191017225518555.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[http_localhost_8765_hi_message_HelloFeign]: http://localhost:8765/hi?message=HelloFeign
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20191017225425548.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[https_download.csdn.net_download_badao_liumang_qizhi_11871136]: https://download.csdn.net/download/badao_liumang_qizhi/11871136