Spring Boot集成Spring Retry快速入门Demo

1.Retry介绍

Spring Retry

提供了自动重新调用失败的操作的功能。这在错误可能是暂时的（例如瞬时网络故障）的情况下很有用。从2.2.0版本开始，重试功能已从Spring Batch中撤出，成为一个独立的新库：Spring Retry

使用场景

在日常开发过程中，难免会与第三方接口发生交互，例如：短信发送、远程服务调用、争抢锁等场景，当正常调用发生异常时，例如：网络抖动，这些间歇性的异常在一段时候之后会自行恢复，程序为了更加健壮并且更不容易出现故障，需要重新触发业务操作，以防止间歇性的异常对程序照成的影响。

tips：幂等性

非幂等的情况下要小心使用重试。HTTP/1.1中对幂等性的定义是：一次和多次请求某一个资源对于资源本身应该具有同样的结果（网络超时等问题除外）。也就是说，其任意多次执行对资源本身所产生的影响均与一次执行的影响相同。

2.代码工程

实验目标：模拟三方接口异常，触发重试

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"><parent><artifactId>springboot-demo</artifactId><groupId>com.et</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>SpringRetry</artifactId><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-autoconfigure</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><!--retry--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.retry</groupId><artifactId>spring-retry</artifactId></dependency><dependency><groupId>org.aspectj</groupId><artifactId>aspectjweaver</artifactId></dependency></dependencies>
</project>

application.yaml

server:port: 8088

RemoteApiService.java

@Retryable注解，value值表示当哪些异常的时候触发重试，maxAttempts表示最大重试次数默认为3，delay表示重试的延迟时间，multiplier表示上一次延时时间是这一次的倍数。
@Recover注解，当重试次数达到设置的次数的时候，还是失败抛出异常，执行的回调函数。

package com.et.retry.service;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.retry.annotation.Backoff;
import org.springframework.retry.annotation.Recover;
import org.springframework.retry.annotation.Retryable;
import org.springframework.stereotype.Service;import java.time.LocalDateTime;
import java.time.LocalTime;@Service
public class RemoteApiService {private Logger logger = LoggerFactory.getLogger(getClass());@Retryable(value = Exception.class,maxAttempts = 3,backoff = @Backoff(delay = 2000,multiplier = 1.5))public boolean pay(int num) throws Exception{logger.info("invoke third method");logger.info("do something... {}", LocalDateTime.now());//mock exceptionif(num==0) {throw new Exception("error，need retry");}return true;}@Recoverpublic boolean recover(int num) throws Exception {logger.info("recover ... {},{}", num, LocalDateTime.now());return false;}}

DemoApplication.java

在主类上加上@EnableRetry注解，表示启用重试机制。

package com.et.retry;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.retry.annotation.EnableRetry;@SpringBootApplication
@EnableRetry
public class DemoApplication {public static void main(String[] args) {SpringApplication.run(DemoApplication.class, args);}
}

以上只是一些关键代码，所有代码请参见下面代码仓库

代码仓库

https://github.com/Harries/springboot-demo

3.测试

编写测试类

package com.et.retry;import com.et.retry.service.RemoteApiService;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;@RunWith(SpringRunner.class)
@SpringBootTest(classes = DemoApplication.class)
public class DemoTests {private Logger log = LoggerFactory.getLogger(getClass());@AutowiredRemoteApiService remoteApiService;@Beforepublic void before()  {log.info("init some data");}@Afterpublic void after(){log.info("clean some data");}@Testpublic void execute() throws Exception {log.info("pay result:"+remoteApiService.pay(0));}}

运行测试方法，结果如下

2024-04-03 10:35:54.738 INFO 13096 --- [ main] com.et.retry.DemoTests : init some data
2024-04-03 10:35:54.756 INFO 13096 --- [ main] com.et.retry.service.RemoteApiService : invoke third method
2024-04-03 10:35:54.759 INFO 13096 --- [ main] com.et.retry.service.RemoteApiService : do something... 2024-04-03T10:35:54.758
2024-04-03 10:35:56.766 INFO 13096 --- [ main] com.et.retry.service.RemoteApiService : invoke third method
2024-04-03 10:35:56.766 INFO 13096 --- [ main] com.et.retry.service.RemoteApiService : do something... 2024-04-03T10:35:56.766
2024-04-03 10:35:59.776 INFO 13096 --- [ main] com.et.retry.service.RemoteApiService : invoke third method
2024-04-03 10:35:59.776 INFO 13096 --- [ main] com.et.retry.service.RemoteApiService : do something... 2024-04-03T10:35:59.776
2024-04-03 10:35:59.776 INFO 13096 --- [ main] com.et.retry.service.RemoteApiService : recover ... 0,2024-04-03T10:35:59.776
2024-04-03 10:35:59.776 INFO 13096 --- [ main] com.et.retry.DemoTests : pay result:false
2024-04-03 10:35:59.778 INFO 13096 --- [ main] com.et.retry.DemoTests : clean some data