Java 代码重试实现方式

依赖包

<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>org.examplegroupId>
    <artifactId>learn-demoartifactId>
    <version>1.0-SNAPSHOTversion>

    <properties>
        <maven.compiler.source>20maven.compiler.source>
        <maven.compiler.target>20maven.compiler.target>
        <project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
        <spring.version>3.1.2spring.version>
    properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
            <version>${spring.version}version>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <version>1.18.28version>
        dependency>
        <dependency>
            <groupId>com.alibabagroupId>
            <artifactId>fastjsonartifactId>
            <version>2.0.32version>
        dependency>

			 <dependency>
			     <groupId>org.aspectjgroupId>
			     <artifactId>aspectjweaverartifactId>
			     <version>1.9.19version>
			 dependency>
			 <dependency>
            <groupId>cglibgroupId>
            <artifactId>cglibartifactId>
            <version>3.3.0version>
        dependency>

        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.13.2version>
        dependency>
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-testartifactId>
            <version>6.0.11version>
        dependency>

    dependencies>

project>

一.方法内直接自动重试

    public static void main(String[] args) {
        autoRetry(3);
    }

    /**
     * 自动重试（执行总次数包含于重试次数内）
     * 优点:实现简单
     * 缺点:复用性差，代码侵入
     * @param retryTimes
     */
    public static void autoRetry(int retryTimes){
        int times = 0;
        do {
            try {
                int i = 3/0;
            } catch (Exception e) {
                times++;
                System.out.println("第" + times + "次失败");
            }
        } while (times < retryTimes);
    }

二.静态代理方式

1.启动类

package org.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * @author Administrator
 */
@SpringBootApplication
public class LearnApp {

    public static void main(String[] args) {
        SpringApplication.run(LearnApp.class,args);
    }
}

2.接口

package org.example.service;

/**
 * @description
 * @author zhuwd && moon
 * @version 1.0
 */
public interface LearnService {

    /**
     * 自动重试
     */
    void autoRetry();
}

3.实现

package org.example.service.impl;

import org.example.service.LearnService;
import org.springframework.stereotype.Service;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 1:05
 */
@Service
public class LearnServiceImpl implements LearnService {
    @Override
    public void autoRetry() {
        throw new RuntimeException();
    }
}

4.静态代理

package org.example.service.impl;

import org.example.service.LearnService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 1:06
 */
@Service
public class LearnServiceProxyImpl implements LearnService {

    @Autowired
    private LearnServiceImpl learnService;

    private static final int RETRY_TIMES = 3;

    @Override
    public void autoRetry() {
        int times = 0;
        do {
            try {
                learnService.autoRetry();
            } catch (Exception e) {
                times++;
                System.out.println("第" + times + "次失败");
            }
        } while (times < RETRY_TIMES);
    }
}

5.单元测试类

import org.example.LearnApp;
import org.example.service.impl.LearnServiceProxyImpl;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 1:11
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = LearnApp.class)
public class LearnTest {

    @Autowired
    LearnServiceProxyImpl learnServiceProxy;

    @Test
    public void test(){
        learnServiceProxy.autoRetry();
    }

}

三.JDK 动态代理

1.代理类

package org.example.proxy;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

/**
 * @author zhuwd && moon
 * @Description 实现方式较优雅，但是被代理的类必须实现某个接口才能操作
 * @create 2023-08-08 21:14
 */
public class RetryInvocationHandler implements InvocationHandler {

    private static final int RETRY_TIMES = 3;

    /**
     * 目标对象
     */
    private final Object target;

    /**
     * 有参构造
     * @param target
     */
    public RetryInvocationHandler(Object target) {
        this.target = target;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        int times = 0;
        do {
            try {
                return method.invoke(target,args);
            } catch (Exception e) {
                times++;
                System.out.println("第" + times + "次失败");
            }
        } while (times < RETRY_TIMES);
        return null;
    }
}

2.单元测试

import org.example.LearnApp;
import org.example.proxy.RetryInvocationHandler;
import org.example.service.LearnService;
import org.example.service.impl.LearnServiceImpl;
import org.example.service.impl.LearnServiceProxyImpl;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 1:11
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = LearnApp.class)
public class LearnTest {

    @Autowired
    LearnServiceImpl learnService;

    @Test
    public void testJdk(){
        InvocationHandler handler = new RetryInvocationHandler(learnService);
        LearnService service = (LearnService) Proxy.newProxyInstance(handler.getClass().getClassLoader(), learnService.getClass().getInterfaces(),handler);
        service.autoRetry();
    }
}

四.CGLIB 动态代理

注意依赖选择 cglib 包下的，不要用 spring 下的

1.动态代理类

package org.example.proxy;


import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

import java.lang.reflect.Method;


/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 21:25
 */
public class CGLibRetryProxyHandler implements MethodInterceptor {

    private static final int RETRY_TIMES = 3;
    private Object target;

    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
        int times = 0;
        do {
            try {
                return method.invoke(target,objects);
            } catch (Exception e) {
                times++;
                System.out.println("第" + times + "次失败");
            }
        } while (times < RETRY_TIMES);
        return null;
    }

    /**
     * 生产代理类
     * @param target
     * @return
     */
    public Object getProxy(Object target){
        this.target = target;
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(this.target.getClass());
        enhancer.setCallback(this);
        enhancer.setClassLoader(this.target.getClass().getClassLoader());
        Object proxy = enhancer.create();
        return proxy;
    }

}

2.单元测试

import org.example.LearnApp;
import org.example.proxy.CGLibRetryProxyHandler;
import org.example.service.LearnService;
import org.example.service.impl.LearnServiceImpl;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 1:11
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = LearnApp.class)
public class LearnTest {

    @Autowired
    LearnServiceImpl learnService;

    @Test
    public void testCglib(){
        CGLibRetryProxyHandler handler = new CGLibRetryProxyHandler();
        LearnService service = (LearnService) handler.getProxy(learnService);
        service.autoRetry();
    }
}

如果是JDK17及以上版本，用IDEA调试需要增加VM配置：--add-opens java.base/java.lang=ALL-UNNAMED

五.手动 AOP

利用自定义注解实现重试AOP逻辑

1.自定义注解

package org.example.anno;

import java.lang.annotation.*;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 22:50
 */
@Documented
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface RetryAnno {

    /**
     * 重试次数
     * @return
     */
    int retryTimes() default 3;

    /**
     * 重试间隔（s）
     * @return
     */
    int retryInterval() default 3;

}

2.重试注解切面

package org.example.config;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.example.anno.RetryAnno;
import org.springframework.stereotype.Component;

import java.util.concurrent.TimeUnit;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 22:52
 */
@Aspect
@Component
public class RetryAspect {

    @Pointcut("@annotation(org.example.anno.RetryAnno)")
    private void retryCall(){};

    @Around("retryCall()")
    public Object retry(ProceedingJoinPoint joinPoint) throws Throwable{
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        RetryAnno retryAnno = signature.getMethod().getAnnotation(RetryAnno.class);
        int retryTimes = retryAnno.retryTimes();
        int retryInterval = retryAnno.retryInterval();
        int times = 0;
        do {
            try {
                return joinPoint.proceed();
            } catch (Exception e) {
                times++;
                System.out.println(System.currentTimeMillis() + "  第" + times + "次失败");
                TimeUnit.SECONDS.sleep(retryInterval);
            }
        } while (times < retryTimes);
        return null;
    }

}

3.测试类

package org.example.config;

import org.example.anno.RetryAnno;
import org.springframework.stereotype.Component;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 23:02
 */
@Component
public class LearnRetry {

    @RetryAnno(retryTimes = 3,retryInterval = 3)
    public void retry(){
        throw new RuntimeException();
    }

}

4.单元测试方法

import org.example.LearnApp;
import org.example.config.LearnRetry;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 1:11
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = LearnApp.class)
public class LearnTest {

    @Autowired
    LearnRetry learnRetry;

    @Test
    public void testAopRetry(){
        learnRetry.retry();
    }
}

六.Spring Retry

<dependency>
    <groupId>org.springframework.retrygroupId>
    <artifactId>spring-retryartifactId>
    <version>2.0.2version>
dependency>

1.测试类

package org.example.config;

import org.springframework.retry.annotation.Backoff;
import org.springframework.retry.annotation.EnableRetry;
import org.springframework.retry.annotation.Recover;
import org.springframework.retry.annotation.Retryable;
import org.springframework.stereotype.Component;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 23:10
 */
@Component
@EnableRetry
public class SpringRetry {

    /**
     * maxAttempts 最大重试次数
     * backoff.delay 重试延迟
     * backoff.multiplier 延迟倍数，即第一次间隔 2S 第二次将间隔 4秒
     */
    @Retryable(maxAttempts = 3,backoff = @Backoff(delay = 2000,multiplier = 2))
    public void retry(){
        System.out.println(System.currentTimeMillis() + "  重试 ...");
        throw new RuntimeException();
    }

    /**
     * @Recover 注解必须和 @Retryable 在同一个类；且返回值一致不能抛出额外异常
     *
     * @param e
     */
    @Recover
    public void recover(RuntimeException e){
        System.out.println("已达最大重试次数");
    }

}

2.单元测试类

import org.example.LearnApp;
import org.example.config.SpringRetry;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 1:11
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = LearnApp.class)
public class LearnTest {


    @Autowired
    SpringRetry springRetry;

    @Test
    public void testSpringRetry(){
        springRetry.retry();
    }
}

3.单元测试方法

import org.example.LearnApp;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.retry.backoff.FixedBackOffPolicy;
import org.springframework.retry.policy.SimpleRetryPolicy;
import org.springframework.retry.support.RetryTemplate;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import java.util.HashMap;
import java.util.Map;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 1:11
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = LearnApp.class)
public class LearnTest {

    public void retry(){
        System.out.println(System.currentTimeMillis() + "  重试 ...");
        throw new RuntimeException();
    }

    @Test
    public void testSpringRetryMethod(){

        RetryTemplate template = new RetryTemplate();

        /**
         * 重试策略
         */
        Map<Class<? extends Throwable>,Boolean> map = new HashMap<>();
        map.put(RuntimeException.class,true);
        SimpleRetryPolicy retryPolicy = new SimpleRetryPolicy(3,map);

        /**
         * 重试回退策略
         */
        FixedBackOffPolicy backOffPolicy = new FixedBackOffPolicy();
        backOffPolicy.setBackOffPeriod(2000);

        template.setRetryPolicy(retryPolicy);
        template.setBackOffPolicy(backOffPolicy);

        Boolean execute = template.execute(retryContext -> {
            retry();
            return true;
        },retryContext -> {
            System.out.println("已达最大重试次数");
            return false;
        });

        System.out.println("调用结果 " + execute);
    }
}

七.Guava Retry

<dependency>
    <groupId>com.github.rholdergroupId>
    <artifactId>guava-retryingartifactId>
    <version>2.0.0version>
dependency>

1.测试类

package org.example.config;

import org.springframework.stereotype.Component;

/**
 * @author zhuwd && moon
 * @Description 10S 后返回正确值
 * @create 2023-08-08 23:49
 */
@Component
public class GuavaRetry {

    private static long init_time = System.currentTimeMillis() + 1000 * 10;

    public int retry(){
        if (System.currentTimeMillis() > init_time){
            return 0;
        }
        return -1;
    }


}

2.单元测试

import com.github.rholder.retry.*;
import org.example.LearnApp;
import org.example.config.GuavaRetry;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import java.util.Objects;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

/**
 * @author zhuwd && moon
 * @Description
 * @create 2023-08-08 1:11
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = LearnApp.class)
public class LearnTest {

    @Autowired
    GuavaRetry guavaRetry;

    @Test
    public void testGuavaRetry(){
        Retryer<Integer> retryer = RetryerBuilder.<Integer>newBuilder()
                //根据异常重试
                .retryIfException()
                //根据结果重试
                .retryIfResult(result-> !Objects.equals(result,0))
                //重试策略
                .withWaitStrategy(WaitStrategies.fixedWait(2, TimeUnit.SECONDS))
                //停止策略
                .withStopStrategy(StopStrategies.stopAfterAttempt(300))
                //监听重试进度
                .withRetryListener(new RetryListener() {
                    @Override
                    public <V> void onRetry(Attempt<V> attempt) {
                        System.out.println(System.currentTimeMillis() + "  第" + attempt.getAttemptNumber() + "次失败");
                    }
                })
                .build();

        try {
            int result = retryer.call(()->guavaRetry.retry());
            System.out.println("调用结果：" + result);
        } catch (ExecutionException e) {
            throw new RuntimeException(e);
        } catch (RetryException e) {
            throw new RuntimeException(e);
        }
    }

}