Retry重試機制

對於重試機制有兩個一個是Guava，另外一個是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>

測試方法

Retryer<Boolean> retryer = RetryerBuilder.<Boolean>newBuilder()
        .retryIfExceptionOfType(Exception.class)
        //返回false也須要重試
        .retryIfResult(Predicates.equalTo(false))
        //重調策略
        .withWaitStrategy(WaitStrategies.fixedWait(1, TimeUnit.SECONDS))
        //嘗試次數
        .withStopStrategy(StopStrategies.stopAfterAttempt(3))
        .build();
try {
    //執行指定的方法。
    retryer.call(() -> {
        System.err.println("do something...");
        throw new Exception("我是一個異常!");
    });
} catch (ExecutionException e) {
    e.printStackTrace();
} catch (RetryException e) {
    e.printStackTrace();
}

測試結果

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: 我是一個異常!
    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

擴展介紹

TODO...

spring-retry

pom

引入Spring-retry和aspectjweaver的依賴

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

修改啓動類

須要在啓動類上加入@EnableRetry註解

須要重試的方法

在須要重試的方法上加入

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

@Retryable的參數說明

• value：拋出指定異常纔會重試
• include：和value同樣，默認爲空，當exclude也爲空時，默認因此異常
• exclude：指定不處理的異常
• maxAttempts：最大重試次數，默認3次
• backoff：重試等待策略，默認使用@Backoff，@Backoff的value默認爲1000L，咱們設置爲2000L；multiplier（指定延遲倍數）默認爲0，表示固定暫停1秒後進行重試，若是把multiplier設置爲1.5，則第一次重試爲2秒，第二次爲3秒，第三次爲4.5秒。