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Retry重试机制

对于重试机制有两个一个是Guava，另一个是spring的。

Guava retryer工具

pom引用

<dependency>
      <groupId>com.github.rholder</groupId>
      <artifactId>guava-retrying</artifactId>
      <version>2.0.0</version>
</dependency>

测试方法

Retryer<Boolean> retryer = RetryerBuilder.<Boolean>newBuilder()
        .retryIfExceptionOfType(Exception.class)
        //返回false也需要重试
        .retryIfResult(Predicates.equalTo(false))
        //重调策略
        .withWaitStrategy(WaitStrategies.fixedWait(1, TimeUnit.SECONDS))
        //尝试次数
        .withStopStrategy(StopStrategies.stopAfterAttempt(3))
        .build();
try {
    //执行指定的方法。
    retryer.call(() -> {
        System.err.println("do something...");
        throw new Exception("我是一个异常!");
    });
} catch (ExecutionException e) {
    e.printStackTrace();
} catch (RetryException e) {
    e.printStackTrace();
}

测试结果

do something...
do something...
do something...
com.github.rholder.retry.RetryException: Retrying failed to complete successfully after 3 attempts.
    at com.github.rholder.retry.Retryer.call(Retryer.java:174)
    at com.utils.UtilsTest.retryTest(UtilsTest.java:46)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: java.lang.Exception: 我是一个异常!
    at com.utils.UtilsTest.lambda$retryTest$0(UtilsTest.java:48)
    at com.github.rholder.retry.AttemptTimeLimiters$NoAttemptTimeLimit.call(AttemptTimeLimiters.java:78)
    at com.github.rholder.retry.Retryer.call(Retryer.java:160)
    ... 29 more

扩展介绍

TODO...

spring-retry

pom

引入 Spring-retry 和 aspectjweaver 的依赖

<dependency>
    <groupId>org.springframework.retry</groupId>
    <artifactId>spring-retry</artifactId>
</dependency>
<dependency>
    <groupId>org.aspectj</groupId>
    <artifactId>aspectjweaver</artifactId>
</dependency>

修改启动类

需要在启动类上加入 @EnableRetry 注解

需要重试的方法

在需要重试的方法上加入

@Retryable(value = Exception.class, maxAttempts = 3, backoff = @Backoff(delay = 2000L, multiplier = 1.5))

`@Retryable` 的参数说明

value：抛出指定异常才会重试
include：和value一样，默认为空，当exclude也为空时，默认所以异常
exclude：指定不处理的异常
maxAttempts：最大重试次数，默认3次
backoff：重试等待策略，默认使用 @Backoff ， @Backoff 的value默认为1000L，我们设置为2000L；multiplier（指定延迟倍数）默认为0，表示固定暂停1秒后进行重试，如果把multiplier设置为1.5，则第一次重试为2秒，第二次为3秒，第三次为4.5秒。

原文 https://segmentfault.com/a/1190000021257372

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