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今天小編給大家分享一下Spring Boot中怎么使用Spring Retry重試框架的相關(guān)知識(shí)點(diǎn)，內(nèi)容詳細(xì)，邏輯清晰，相信大部分人都還太了解這方面的知識(shí)，所以分享這篇文章給大家參考一下，希望大家閱讀完這篇文章后有所收獲，下面我們一起來了解一下吧。
Spring Retry提供了自動(dòng)重新調(diào)用失敗的操作的功能。這在錯(cuò)誤可能是暫時(shí)的（例如瞬時(shí)網(wǎng)絡(luò)故障）的情況下很有用。 從2.2.0版本開始，重試功能已從Spring Batch中撤出，成為一個(gè)獨(dú)立的新庫：Spring Retry
<dependency> <groupId>org.springframework.retry</groupId> <artifactId>spring-retry</artifactId> </dependency> <!-- also need to add Spring AOP into our project--> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aspects</artifactId> </dependency>
在啟動(dòng)類中使用@EnableRetry注解
package org.example;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.retry.annotation.EnableRetry;
@SpringBootApplication
@EnableRetry
public class RetryApp {
public static void main(String[] args) {
SpringApplication.run(RetryApp.class, args);
}
}需要在重試的代碼中加入重試注解@Retryable
package org.example;
import lombok.extern.slf4j.Slf4j;
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;
@Service
@Slf4j
public class RetryService {
@Retryable(value = IllegalAccessException.class)
public void service1() throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException("manual exception");
}
}默認(rèn)情況下，會(huì)重試3次，間隔1秒
我們可以從注解@Retryable中看到
@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Retryable {
/**
* Retry interceptor bean name to be applied for retryable method. Is mutually
* exclusive with other attributes.
* @return the retry interceptor bean name
*/
String interceptor() default "";
* Exception types that are retryable. Synonym for includes(). Defaults to empty (and
* if excludes is also empty all exceptions are retried).
* @return exception types to retry
Class<? extends Throwable>[] value() default {};
* Exception types that are retryable. Defaults to empty (and if excludes is also
* empty all exceptions are retried).
Class<? extends Throwable>[] include() default {};
* Exception types that are not retryable. Defaults to empty (and if includes is also
* If includes is empty but excludes is not, all not excluded exceptions are retried
* @return exception types not to retry
Class<? extends Throwable>[] exclude() default {};
* A unique label for statistics reporting. If not provided the caller may choose to
* ignore it, or provide a default.
*
* @return the label for the statistics
String label() default "";
* Flag to say that the retry is stateful: i.e. exceptions are re-thrown, but the
* retry policy is applied with the same policy to subsequent invocations with the
* same arguments. If false then retryable exceptions are not re-thrown.
* @return true if retry is stateful, default false
boolean stateful() default false;
* @return the maximum number of attempts (including the first failure), defaults to 3
int maxAttempts() default 3; //默認(rèn)重試次數(shù)3次
* @return an expression evaluated to the maximum number of attempts (including the first failure), defaults to 3
* Overrides {@link #maxAttempts()}.
* @since 1.2
String maxAttemptsExpression() default "";
* Specify the backoff properties for retrying this operation. The default is a
* simple {@link Backoff} specification with no properties - see it's documentation
* for defaults.
* @return a backoff specification
Backoff backoff() default @Backoff(); //默認(rèn)的重試中的退避策略
* Specify an expression to be evaluated after the {@code SimpleRetryPolicy.canRetry()}
* returns true - can be used to conditionally suppress the retry. Only invoked after
* an exception is thrown. The root object for the evaluation is the last {@code Throwable}.
* Other beans in the context can be referenced.
* For example:
* <pre class=code>
* {@code "message.contains('you can retry this')"}.
* </pre>
* and
* {@code "@someBean.shouldRetry(#root)"}.
* @return the expression.
String exceptionExpression() default "";
* Bean names of retry listeners to use instead of default ones defined in Spring context
* @return retry listeners bean names
String[] listeners() default {};
}@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Backoff {
/**
* Synonym for {@link #delay()}.
*
* @return the delay in milliseconds (default 1000)
*/
long value() default 1000; //默認(rèn)的重試間隔1秒
* A canonical backoff period. Used as an initial value in the exponential case, and
* as a minimum value in the uniform case.
* @return the initial or canonical backoff period in milliseconds (default 1000)
long delay() default 0;
* The maximimum wait (in milliseconds) between retries. If less than the
* {@link #delay()} then the default of
* {@value org.springframework.retry.backoff.ExponentialBackOffPolicy#DEFAULT_MAX_INTERVAL}
* is applied.
* @return the maximum delay between retries (default 0 = ignored)
long maxDelay() default 0;
* If positive, then used as a multiplier for generating the next delay for backoff.
* @return a multiplier to use to calculate the next backoff delay (default 0 =
* ignored)
double multiplier() default 0;
* An expression evaluating to the canonical backoff period. Used as an initial value
* in the exponential case, and as a minimum value in the uniform case. Overrides
* {@link #delay()}.
* @return the initial or canonical backoff period in milliseconds.
* @since 1.2
String delayExpression() default "";
* An expression evaluating to the maximimum wait (in milliseconds) between retries.
* If less than the {@link #delay()} then the default of
* is applied. Overrides {@link #maxDelay()}
String maxDelayExpression() default "";
* Evaluates to a vaule used as a multiplier for generating the next delay for
* backoff. Overrides {@link #multiplier()}.
* @return a multiplier expression to use to calculate the next backoff delay (default
* 0 = ignored)
String multiplierExpression() default "";
* In the exponential case ({@link #multiplier()} > 0) set this to true to have the
* backoff delays randomized, so that the maximum delay is multiplier times the
* previous delay and the distribution is uniform between the two values.
* @return the flag to signal randomization is required (default false)
boolean random() default false;
}我們來運(yùn)行測(cè)試代碼
package org.example;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest
class RetryServiceTest {
@Autowired
private RetryService retryService;
@Test
void testService1() throws IllegalAccessException {
retryService.service1();
}
}運(yùn)行結(jié)果如下：
2021-01-05 19:40:41.221 INFO 3548 --- [ main] org.example.RetryService : do something... 2021-01-05T19:40:41.221763300
2021-01-05 19:40:42.224 INFO 3548 --- [ main] org.example.RetryService : do something... 2021-01-05T19:40:42.224436500
2021-01-05 19:40:43.225 INFO 3548 --- [ main] org.example.RetryService : do something... 2021-01-05T19:40:43.225189300
java.lang.IllegalAccessException: manual exception at org.example.RetryService.service1(RetryService.java:19) at org.example.RetryService$$FastClassBySpringCGLIB$$c0995ddb.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:769) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747) at org.springframework.retry.interceptor.RetryOperationsInterceptor$1.doWithRetry(RetryOperationsInterceptor.java:91) at org.springframework.retry.support.RetryTemplate.doExecute(RetryTemplate.java:287) at org.springframework.retry.support.RetryTemplate.execute(RetryTemplate.java:164) at org.springframework.retry.interceptor.RetryOperationsInterceptor.invoke(RetryOperationsInterceptor.java:118) at org.springframework.retry.annotation.AnnotationAwareRetryOperationsInterceptor.invoke(AnnotationAwareRetryOperationsInterceptor.java:153) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689) at org.example.RetryService$$EnhancerBySpringCGLIB$$499afa1d.service1(<generated>) at org.example.RetryServiceTest.testService1(RetryServiceTest.java:16) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:675) at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60) at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:125) at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:132) at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:124) at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:74) at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115) at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105) at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:104) at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:62) at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:43) at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:35) at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104) at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:202) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:198) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:69) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:135) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125) at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123) at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122) at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80) at java.base/java.util.ArrayList.forEach(ArrayList.java:1540) at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139) at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32) at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57) at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51) at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:229) at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$6(DefaultLauncher.java:197) at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:211) at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:191) at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:128) at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71) at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33) at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:220) at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:53)
可以看到重新執(zhí)行了3次service1()方法，然后間隔是1秒，然后最后還是重試失敗，所以拋出了異常
既然我們看到了注解@Retryable中有這么多參數(shù)可以設(shè)置，那我們就來介紹幾個(gè)常用的配置。
@Retryable(include = IllegalAccessException.class, maxAttempts = 5)
public void service2() throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException("manual exception");
}首先是maxAttempts，用于設(shè)置重試次數(shù)
2021-01-06 09:30:11.263 INFO 15612 --- [ main] org.example.RetryService : do something... 2021-01-06T09:30:11.263621900
2021-01-06 09:30:12.265 INFO 15612 --- [ main] org.example.RetryService : do something... 2021-01-06T09:30:12.265629100
2021-01-06 09:30:13.265 INFO 15612 --- [ main] org.example.RetryService : do something... 2021-01-06T09:30:13.265701
2021-01-06 09:30:14.266 INFO 15612 --- [ main] org.example.RetryService : do something... 2021-01-06T09:30:14.266705400
2021-01-06 09:30:15.266 INFO 15612 --- [ main] org.example.RetryService : do something... 2021-01-06T09:30:15.266733200java.lang.IllegalAccessException: manual exception
....
從運(yùn)行結(jié)果可以看到，方法執(zhí)行了5次。
下面來介紹maxAttemptsExpression的設(shè)置
@Retryable(value = IllegalAccessException.class, maxAttemptsExpression = "${maxAttempts}")
public void service3() throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException("manual exception");
}maxAttemptsExpression則可以使用表達(dá)式，比如上述就是通過獲取配置中maxAttempts的值，我們可以在application.yml設(shè)置。上述其實(shí)省略掉了SpEL表達(dá)式#{....}，運(yùn)行結(jié)果的話可以發(fā)現(xiàn)方法執(zhí)行了4次..
maxAttempts: 4
我們可以使用SpEL表達(dá)式
@Retryable(value = IllegalAccessException.class, maxAttemptsExpression = "#{1+1}")
public void service3_1() throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException("manual exception");
}
@Retryable(value = IllegalAccessException.class, maxAttemptsExpression = "#{${maxAttempts}}")//效果和上面的一樣
public void service3_2() throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException("manual exception");
}接著我們下面來看看exceptionExpression, 一樣也是寫SpEL表達(dá)式
@Retryable(value = IllegalAccessException.class, exceptionExpression = "message.contains('test')")
public void service4(String exceptionMessage) throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException(exceptionMessage);
}
@Retryable(value = IllegalAccessException.class, exceptionExpression = "#{message.contains('test')}")
public void service4_3(String exceptionMessage) throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException(exceptionMessage);
}上面的表達(dá)式exceptionExpression = "message.contains('test')"的作用其實(shí)是獲取到拋出來exception的message(調(diào)用了getMessage()方法)，然后判斷message的內(nèi)容里面是否包含了test字符串，如果包含的話就會(huì)執(zhí)行重試。所以如果調(diào)用方法的時(shí)候傳入的參數(shù)exceptionMessage中包含了test字符串的話就會(huì)執(zhí)行重試。
但這里值得注意的是, Spring Retry 1.2.5之后exceptionExpression是可以省略掉#{...}
Since Spring Retry 1.2.5, for exceptionExpression, templated expressions (#{...}) are deprecated in favor of simple expression strings (message.contains('this can be retried')).
使用1.2.5之后的版本運(yùn)行是沒有問題的
<dependency> <groupId>org.springframework.retry</groupId> <artifactId>spring-retry</artifactId> <version>1.3.0</version> </dependency>
但是如果使用1.2.5版本之前包括1.2.5版本的話，運(yùn)行的時(shí)候會(huì)報(bào)錯(cuò)如下：
2021-01-06 09:52:45.209 INFO 23220 --- [ main] org.example.RetryService : do something... 2021-01-06T09:52:45.209178200
org.springframework.expression.spel.SpelEvaluationException: EL1001E: Type conversion problem, cannot convert from java.lang.String to java.lang.Boolean
at org.springframework.expression.spel.support.StandardTypeConverter.convertValue(StandardTypeConverter.java:75)
at org.springframework.expression.common.ExpressionUtils.convertTypedValue(ExpressionUtils.java:57)
at org.springframework.expression.common.LiteralExpression.getValue(LiteralExpression.java:106)
at org.springframework.retry.policy.ExpressionRetryPolicy.canRetry(ExpressionRetryPolicy.java:113)
at org.springframework.retry.support.RetryTemplate.canRetry(RetryTemplate.java:375)
at org.springframework.retry.support.RetryTemplate.doExecute(RetryTemplate.java:304)
at org.springframework.retry.support.RetryTemplate.execute(RetryTemplate.java:164)
at org.springframework.retry.interceptor.RetryOperationsInterceptor.invoke(RetryOperationsInterceptor.java:118)
at org.springframework.retry.annotation.AnnotationAwareRetryOperationsInterceptor.invoke(AnnotationAwareRetryOperationsInterceptor.java:153)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:691)
at org.example.RetryService$$EnhancerBySpringCGLIB$$d321a75e.service4(<generated>)
at org.example.RetryServiceTest.testService4_2(RetryServiceTest.java:46)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:686)
at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:212)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:208)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:137)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:71)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:135)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1540)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:248)
at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$5(DefaultLauncher.java:211)
at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:226)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:199)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:132)
at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:220)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:53)
Caused by: org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [java.lang.Boolean] for value 'message.contains('test')'; nested exception is java.lang.IllegalArgumentException: Invalid boolean value 'message.contains('test')'
at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:47)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:191)
at org.springframework.expression.spel.support.StandardTypeConverter.convertValue(StandardTypeConverter.java:70)
... 76 more
Caused by: java.lang.IllegalArgumentException: Invalid boolean value 'message.contains('test')'
at org.springframework.core.convert.support.StringToBooleanConverter.convert(StringToBooleanConverter.java:63)
at org.springframework.core.convert.support.StringToBooleanConverter.convert(StringToBooleanConverter.java:31)
at org.springframework.core.convert.support.GenericConversionService$ConverterAdapter.convert(GenericConversionService.java:385)
at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:41)
... 78 more
還可以在表達(dá)式中執(zhí)行一個(gè)方法，前提是方法的類在spring容器中注冊(cè)了，@retryService其實(shí)就是獲取bean name為retryService的bean，然后調(diào)用里面的checkException方法，傳入的參數(shù)為#root，它其實(shí)就是拋出來的exception對(duì)象。一樣的也是可以省略#{...}
@Retryable(value = IllegalAccessException.class, exceptionExpression = "#{@retryService.checkException(#root)}")
public void service5(String exceptionMessage) throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException(exceptionMessage);
}
@Retryable(value = IllegalAccessException.class, exceptionExpression = "@retryService.checkException(#root)")
public void service5_1(String exceptionMessage) throws IllegalAccessException {
public boolean checkException(Exception e) {
log.error("error message:{}", e.getMessage());
return true; //返回true的話表明會(huì)執(zhí)行重試，如果返回false則不會(huì)執(zhí)行重試運(yùn)行結(jié)果：
2021-01-06 13:33:52.913 INFO 23052 --- [ main] org.example.RetryService : do something... 2021-01-06T13:33:52.913404
2021-01-06 13:33:52.981 ERROR 23052 --- [ main] org.example.RetryService : error message:test message
2021-01-06 13:33:53.990 ERROR 23052 --- [ main] org.example.RetryService : error message:test message
2021-01-06 13:33:53.990 INFO 23052 --- [ main] org.example.RetryService : do something... 2021-01-06T13:33:53.990947400
2021-01-06 13:33:53.990 ERROR 23052 --- [ main] org.example.RetryService : error message:test message
2021-01-06 13:33:54.992 ERROR 23052 --- [ main] org.example.RetryService : error message:test message
2021-01-06 13:33:54.992 INFO 23052 --- [ main] org.example.RetryService : do something... 2021-01-06T13:33:54.992342900
當(dāng)然還有更多表達(dá)式的用法了...
@Retryable(exceptionExpression = "#{#root instanceof T(java.lang.IllegalAccessException)}") //判斷exception的類型
public void service5_2(String exceptionMessage) {
log.info("do something... {}", LocalDateTime.now());
throw new NullPointerException(exceptionMessage);
}
@Retryable(exceptionExpression = "#root instanceof T(java.lang.IllegalAccessException)")
public void service5_3(String exceptionMessage) {
log.info("do something... {}", LocalDateTime.now());
throw new NullPointerException(exceptionMessage);
} @Retryable(exceptionExpression = "myMessage.contains('test')") //查看自定義的MyException中的myMessage的值是否包含test字符串
public void service5_4(String exceptionMessage) throws MyException {
log.info("do something... {}", LocalDateTime.now());
throw new MyException(exceptionMessage); //自定義的exception
}
@Retryable(exceptionExpression = "#root.myMessage.contains('test')") //和上面service5_4方法的效果一樣
public void service5_5(String exceptionMessage) throws MyException {
log.info("do something... {}", LocalDateTime.now());
throw new MyException(exceptionMessage);
}package org.example;
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class MyException extends Exception {
private String myMessage;
public MyException(String myMessage) {
this.myMessage = myMessage;
}
}下面再來看看另一個(gè)配置exclude
@Retryable(exclude = MyException.class)
public void service6(String exceptionMessage) throws MyException {
log.info("do something... {}", LocalDateTime.now());
throw new MyException(exceptionMessage);
}這個(gè)exclude屬性可以幫我們排除一些我們不想重試的異常
最后我們來看看這個(gè)backoff 重試等待策略, 默認(rèn)使用@Backoff注解。
我們先來看看這個(gè)@Backoff的value屬性,用于設(shè)置重試間隔
@Retryable(value = IllegalAccessException.class,
backoff = @Backoff(value = 2000))
public void service7() throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException();
}運(yùn)行結(jié)果可以看出來重試的間隔為2秒
2021-01-06 14:47:38.036 INFO 21116 --- [ main] org.example.RetryService : do something... 2021-01-06T14:47:38.036732600
2021-01-06 14:47:40.038 INFO 21116 --- [ main] org.example.RetryService : do something... 2021-01-06T14:47:40.037753600
2021-01-06 14:47:42.046 INFO 21116 --- [ main] org.example.RetryService : do something... 2021-01-06T14:47:42.046642900
java.lang.IllegalAccessException
at org.example.RetryService.service7(RetryService.java:113)
...
接下來介紹@Backoff的delay屬性，它與value屬性不能共存，當(dāng)delay不設(shè)置的時(shí)候會(huì)去讀value屬性設(shè)置的值，如果delay設(shè)置的話則會(huì)忽略value屬性
@Retryable(value = IllegalAccessException.class,
backoff = @Backoff(value = 2000,delay = 500))
public void service8() throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException();
}運(yùn)行結(jié)果可以看出，重試的時(shí)間間隔為500ms
2021-01-06 15:22:42.271 INFO 13512 --- [ main] org.example.RetryService : do something... 2021-01-06T15:22:42.271504800
2021-01-06 15:22:42.772 INFO 13512 --- [ main] org.example.RetryService : do something... 2021-01-06T15:22:42.772234900
2021-01-06 15:22:43.273 INFO 13512 --- [ main] org.example.RetryService : do something... 2021-01-06T15:22:43.273246700
java.lang.IllegalAccessException
at org.example.RetryService.service8(RetryService.java:121)
接下來我們來看``@Backoff的multiplier`的屬性, 指定延遲倍數(shù), 默認(rèn)為0。
@Retryable(value = IllegalAccessException.class,maxAttempts = 4,
backoff = @Backoff(delay = 2000, multiplier = 2))
public void service9() throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException();
}multiplier設(shè)置為2，則表示第一次重試間隔為2s，第二次為4秒，第三次為8s
運(yùn)行結(jié)果如下：
2021-01-06 15:58:07.458 INFO 23640 --- [ main] org.example.RetryService : do something... 2021-01-06T15:58:07.458245500
2021-01-06 15:58:09.478 INFO 23640 --- [ main] org.example.RetryService : do something... 2021-01-06T15:58:09.478681300
2021-01-06 15:58:13.478 INFO 23640 --- [ main] org.example.RetryService : do something... 2021-01-06T15:58:13.478921900
2021-01-06 15:58:21.489 INFO 23640 --- [ main] org.example.RetryService : do something... 2021-01-06T15:58:21.489240600
java.lang.IllegalAccessException
at org.example.RetryService.service9(RetryService.java:128)
...
接下來我們來看看這個(gè)@Backoff的maxDelay屬性,設(shè)置最大的重試間隔，當(dāng)超過這個(gè)最大的重試間隔的時(shí)候，重試的間隔就等于maxDelay的值
@Retryable(value = IllegalAccessException.class,maxAttempts = 4,
backoff = @Backoff(delay = 2000, multiplier = 2,maxDelay = 5000))
public void service10() throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException();
}運(yùn)行結(jié)果：
2021-01-06 16:12:37.377 INFO 5024 --- [ main] org.example.RetryService : do something... 2021-01-06T16:12:37.377616100
2021-01-06 16:12:39.381 INFO 5024 --- [ main] org.example.RetryService : do something... 2021-01-06T16:12:39.381299400
2021-01-06 16:12:43.382 INFO 5024 --- [ main] org.example.RetryService : do something... 2021-01-06T16:12:43.382169500
2021-01-06 16:12:48.396 INFO 5024 --- [ main] org.example.RetryService : do something... 2021-01-06T16:12:48.396327600
java.lang.IllegalAccessException
at org.example.RetryService.service10(RetryService.java:135)
可以最后的最大重試間隔是5秒
當(dāng)@Retryable方法重試失敗之后，最后就會(huì)調(diào)用@Recover方法。用于@Retryable失敗時(shí)的“兜底”處理方法。 @Recover的方法必須要與@Retryable注解的方法保持一致，第一入?yún)橐卦嚨漠惓?，其他參?shù)與@Retryable保持一致，返回值也要一樣，否則無法執(zhí)行！
@Retryable(value = IllegalAccessException.class)
public void service11() throws IllegalAccessException {
log.info("do something... {}", LocalDateTime.now());
throw new IllegalAccessException();
}
@Recover
public void recover11(IllegalAccessException e) {
log.info("service retry after Recover => {}", e.getMessage());
//=========================
@Retryable(value = ArithmeticException.class)
public int service12() throws IllegalAccessException {
return 1 / 0;
public int recover12(ArithmeticException e) {
return 0;
public int service13(String message) throws IllegalAccessException {
log.info("do something... {},{}", message, LocalDateTime.now());
public int recover13(ArithmeticException e, String message) {
log.info("{},service retry after Recover => {}", message, e.getMessage());熔斷模式：指在具體的重試機(jī)制下失敗后打開斷路器，過了一段時(shí)間，斷路器進(jìn)入半開狀態(tài)，允許一個(gè)進(jìn)入重試，若失敗再次進(jìn)入斷路器，成功則關(guān)閉斷路器，注解為@CircuitBreaker,具體包括熔斷打開時(shí)間、重置過期時(shí)間
// openTimeout時(shí)間范圍內(nèi)失敗maxAttempts次數(shù)后，熔斷打開resetTimeout時(shí)長
@CircuitBreaker(openTimeout = 1000, resetTimeout = 3000, value = NullPointerException.class)
public void circuitBreaker(int num) {
log.info(" 進(jìn)入斷路器方法num={}", num);
if (num > 8) return;
Integer n = null;
System.err.println(1 / n);
}
@Recover
public void recover(NullPointerException e) {
log.info("service retry after Recover => {}", e.getMessage());
}測(cè)試方法
@Test
public void testCircuitBreaker() throws InterruptedException {
System.err.println("嘗試進(jìn)入斷路器方法，并觸發(fā)異常...");
retryService.circuitBreaker(1);
retryService.circuitBreaker(1);
retryService.circuitBreaker(9);
retryService.circuitBreaker(9);
System.err.println("在openTimeout 1秒之內(nèi)重試次數(shù)為2次，未達(dá)到觸發(fā)熔斷, 斷路器依然閉合...");
TimeUnit.SECONDS.sleep(1);
System.err.println("超過openTimeout 1秒之后, 因?yàn)槲从|發(fā)熔斷，所以重試次數(shù)重置，可以正常訪問...,繼續(xù)重試3次方法...");
retryService.circuitBreaker(1);
retryService.circuitBreaker(1);
retryService.circuitBreaker(1);
System.err.println("在openTimeout 1秒之內(nèi)重試次數(shù)為3次，達(dá)到觸發(fā)熔斷，不會(huì)執(zhí)行重試，只會(huì)執(zhí)行恢復(fù)方法...");
retryService.circuitBreaker(1);
TimeUnit.SECONDS.sleep(2);
retryService.circuitBreaker(9);
TimeUnit.SECONDS.sleep(3);
System.err.println("超過resetTimeout 3秒之后，斷路器重新閉合...,可以正常訪問");
retryService.circuitBreaker(9);
retryService.circuitBreaker(9);
retryService.circuitBreaker(9);
retryService.circuitBreaker(9);
retryService.circuitBreaker(9);
}運(yùn)行結(jié)果：
嘗試進(jìn)入斷路器方法，并觸發(fā)異常...
2021-01-07 21:44:20.842 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=1
2021-01-07 21:44:20.844 INFO 7464 --- [ main] org.example.RetryService : service retry after Recover => null
2021-01-07 21:44:20.845 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=1
2021-01-07 21:44:20.845 INFO 7464 --- [ main] org.example.RetryService : service retry after Recover => null
2021-01-07 21:44:20.845 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=9
2021-01-07 21:44:20.845 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=9
在openTimeout 1秒之內(nèi)重試次數(shù)為2次，未達(dá)到觸發(fā)熔斷, 斷路器依然閉合...
超過openTimeout 1秒之后, 因?yàn)槲从|發(fā)熔斷，所以重試次數(shù)重置，可以正常訪問...,繼續(xù)重試3次方法...
2021-01-07 21:44:21.846 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=1
2021-01-07 21:44:21.847 INFO 7464 --- [ main] org.example.RetryService : service retry after Recover => null
2021-01-07 21:44:21.847 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=1
2021-01-07 21:44:21.847 INFO 7464 --- [ main] org.example.RetryService : service retry after Recover => null
2021-01-07 21:44:21.847 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=1
2021-01-07 21:44:21.848 INFO 7464 --- [ main] org.example.RetryService : service retry after Recover => null
在openTimeout 1秒之內(nèi)重試次數(shù)為3次，達(dá)到觸發(fā)熔斷，不會(huì)執(zhí)行重試，只會(huì)執(zhí)行恢復(fù)方法...
2021-01-07 21:44:21.848 INFO 7464 --- [ main] org.example.RetryService : service retry after Recover => null
2021-01-07 21:44:23.853 INFO 7464 --- [ main] org.example.RetryService : service retry after Recover => null
超過resetTimeout 3秒之后，斷路器重新閉合...,可以正常訪問
2021-01-07 21:44:26.853 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=9
2021-01-07 21:44:26.854 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=9
2021-01-07 21:44:26.855 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=9
2021-01-07 21:44:26.855 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=9
2021-01-07 21:44:26.856 INFO 7464 --- [ main] org.example.RetryService : 進(jìn)入斷路器方法num=9
package org.example;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.retry.backoff.FixedBackOffPolicy;
import org.springframework.retry.policy.SimpleRetryPolicy;
import org.springframework.retry.support.RetryTemplate;
@Configuration
public class AppConfig {
@Bean
public RetryTemplate retryTemplate() {
RetryTemplate retryTemplate = new RetryTemplate();
SimpleRetryPolicy retryPolicy = new SimpleRetryPolicy(); //設(shè)置重試策略
retryPolicy.setMaxAttempts(2);
retryTemplate.setRetryPolicy(retryPolicy);
FixedBackOffPolicy fixedBackOffPolicy = new FixedBackOffPolicy(); //設(shè)置退避策略
fixedBackOffPolicy.setBackOffPeriod(2000L);
retryTemplate.setBackOffPolicy(fixedBackOffPolicy);
return retryTemplate;
}
}可以看到這些配置跟我們直接寫注解的方式是差不多的，這里就不過多的介紹了。。
package org.example;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.retry.RetryCallback;
import org.springframework.retry.RetryContext;
import org.springframework.retry.support.RetryTemplate;
@SpringBootTest
public class RetryTemplateTest {
@Autowired
private RetryTemplate retryTemplate;
private RetryTemplateService retryTemplateService;
@Test
void test1() throws IllegalAccessException {
retryTemplate.execute(new RetryCallback<Object, IllegalAccessException>() {
@Override
public Object doWithRetry(RetryContext context) throws IllegalAccessException {
retryTemplateService.service1();
return null;
}
});
}
void test2() throws IllegalAccessException {
retryTemplateService.service1();
}, new RecoveryCallback<Object>() {
public Object recover(RetryContext context) throws Exception {
log.info("RecoveryCallback....");
}RetryOperations定義重試的API，RetryTemplate是API的模板模式實(shí)現(xiàn)，實(shí)現(xiàn)了重試和熔斷。提供的API如下:
package org.springframework.retry;
import org.springframework.retry.support.DefaultRetryState;
/**
* Defines the basic set of operations implemented by {@link RetryOperations} to execute
* operations with configurable retry behaviour.
*
* @author Rob Harrop
* @author Dave Syer
*/
public interface RetryOperations {
/**
* Execute the supplied {@link RetryCallback} with the configured retry semantics. See
* implementations for configuration details.
* @param <T> the return value
* @param retryCallback the {@link RetryCallback}
* @param <E> the exception to throw
* @return the value returned by the {@link RetryCallback} upon successful invocation.
* @throws E any {@link Exception} raised by the {@link RetryCallback} upon
* unsuccessful retry.
* @throws E the exception thrown
*/
<T, E extends Throwable> T execute(RetryCallback<T, E> retryCallback) throws E;
* Execute the supplied {@link RetryCallback} with a fallback on exhausted retry to
* the {@link RecoveryCallback}. See implementations for configuration details.
* @param recoveryCallback the {@link RecoveryCallback}
* @param retryCallback the {@link RetryCallback} {@link RecoveryCallback} upon
* @param <T> the type to return
* @param <E> the type of the exception
* @return the value returned by the {@link RetryCallback} upon successful invocation,
* and that returned by the {@link RecoveryCallback} otherwise.
* @throws E any {@link Exception} raised by the unsuccessful retry.
<T, E extends Throwable> T execute(RetryCallback<T, E> retryCallback, RecoveryCallback<T> recoveryCallback)
throws E;
* A simple stateful retry. Execute the supplied {@link RetryCallback} with a target
* object for the attempt identified by the {@link DefaultRetryState}. Exceptions
* thrown by the callback are always propagated immediately so the state is required
* to be able to identify the previous attempt, if there is one - hence the state is
* required. Normal patterns would see this method being used inside a transaction,
* where the callback might invalidate the transaction if it fails.
*
* See implementations for configuration details.
* @param retryState the {@link RetryState}
* @param <T> the type of the return value
* @param <E> the type of the exception to return
* @throws E any {@link Exception} raised by the {@link RecoveryCallback}.
* @throws ExhaustedRetryException if the last attempt for this state has already been
* reached
<T, E extends Throwable> T execute(RetryCallback<T, E> retryCallback, RetryState retryState)
throws E, ExhaustedRetryException;
* A stateful retry with a recovery path. Execute the supplied {@link RetryCallback}
* with a fallback on exhausted retry to the {@link RecoveryCallback} and a target
* object for the retry attempt identified by the {@link DefaultRetryState}.
* @param <T> the return value type
* @param <E> the exception type
* @see #execute(RetryCallback, RetryState)
* @throws E any {@link Exception} raised by the {@link RecoveryCallback} upon
<T, E extends Throwable> T execute(RetryCallback<T, E> retryCallback, RecoveryCallback<T> recoveryCallback,
RetryState retryState) throws E;
}下面主要介紹一下RetryTemplate配置的時(shí)候，需要設(shè)置的重試策略和退避策略
RetryPolicy是一個(gè)接口, 然后有很多具體的實(shí)現(xiàn)，我們先來看看它的接口中定義了什么方法
package org.springframework.retry;
import java.io.Serializable;
/**
* A {@link RetryPolicy} is responsible for allocating and managing resources needed by
* {@link RetryOperations}. The {@link RetryPolicy} allows retry operations to be aware of
* their context. Context can be internal to the retry framework, e.g. to support nested
* retries. Context can also be external, and the {@link RetryPolicy} provides a uniform
* API for a range of different platforms for the external context.
*
* @author Dave Syer
*/
public interface RetryPolicy extends Serializable {
/**
* @param context the current retry status
* @return true if the operation can proceed
*/
boolean canRetry(RetryContext context);
* Acquire resources needed for the retry operation. The callback is passed in so that
* marker interfaces can be used and a manager can collaborate with the callback to
* set up some state in the status token.
* @param parent the parent context if we are in a nested retry.
* @return a {@link RetryContext} object specific to this policy.
*
RetryContext open(RetryContext parent);
* @param context a retry status created by the {@link #open(RetryContext)} method of
* this policy.
void close(RetryContext context);
* Called once per retry attempt, after the callback fails.
* @param context the current status object.
* @param throwable the exception to throw
void registerThrowable(RetryContext context, Throwable throwable);
}我們來看看他有什么具體的實(shí)現(xiàn)類
SimpleRetryPolicy 默認(rèn)最多重試3次
TimeoutRetryPolicy 默認(rèn)在1秒內(nèi)失敗都會(huì)重試
ExpressionRetryPolicy 符合表達(dá)式就會(huì)重試
CircuitBreakerRetryPolicy 增加了熔斷的機(jī)制，如果不在熔斷狀態(tài)，則允許重試
CompositeRetryPolicy 可以組合多個(gè)重試策略
NeverRetryPolicy 從不重試（也是一種重試策略哈）
AlwaysRetryPolicy 總是重試
等等...
看一下退避策略，退避是指怎么去做下一次的重試，在這里其實(shí)就是等待多長時(shí)間。
FixedBackOffPolicy 默認(rèn)固定延遲1秒后執(zhí)行下一次重試
ExponentialBackOffPolicy 指數(shù)遞增延遲執(zhí)行重試，默認(rèn)初始0.1秒，系數(shù)是2，那么下次延遲0.2秒，再下次就是延遲0.4秒，如此類推，最大30秒。
ExponentialRandomBackOffPolicy 在上面那個(gè)策略上增加隨機(jī)性
UniformRandomBackOffPolicy 這個(gè)跟上面的區(qū)別就是，上面的延遲會(huì)不停遞增，這個(gè)只會(huì)在固定的區(qū)間隨機(jī)
StatelessBackOffPolicy 這個(gè)說明是無狀態(tài)的，所謂無狀態(tài)就是對(duì)上次的退避無感知，從它下面的子類也能看出來
等等...
listener可以監(jiān)聽重試，并執(zhí)行對(duì)應(yīng)的回調(diào)方法
package org.springframework.retry;
/**
* Interface for listener that can be used to add behaviour to a retry. Implementations of
* {@link RetryOperations} can chose to issue callbacks to an interceptor during the retry
* lifecycle.
*
* @author Dave Syer
*/
public interface RetryListener {
/**
* Called before the first attempt in a retry. For instance, implementers can set up
* state that is needed by the policies in the {@link RetryOperations}. The whole
* retry can be vetoed by returning false from this method, in which case a
* {@link TerminatedRetryException} will be thrown.
* @param <T> the type of object returned by the callback
* @param <E> the type of exception it declares may be thrown
* @param context the current {@link RetryContext}.
* @param callback the current {@link RetryCallback}.
* @return true if the retry should proceed.
*/
<T, E extends Throwable> boolean open(RetryContext context, RetryCallback<T, E> callback);
* Called after the final attempt (successful or not). Allow the interceptor to clean
* up any resource it is holding before control returns to the retry caller.
* @param throwable the last exception that was thrown by the callback.
* @param <E> the exception type
* @param <T> the return value
<T, E extends Throwable> void close(RetryContext context, RetryCallback<T, E> callback, Throwable throwable);
* Called after every unsuccessful attempt at a retry.
* @param <E> the exception to throw
<T, E extends Throwable> void onError(RetryContext context, RetryCallback<T, E> callback, Throwable throwable);
}使用如下：
自定義一個(gè)Listener
package org.example;
import lombok.extern.slf4j.Slf4j;
import org.springframework.retry.RetryCallback;
import org.springframework.retry.RetryContext;
import org.springframework.retry.listener.RetryListenerSupport;
@Slf4j
public class DefaultListenerSupport extends RetryListenerSupport {
@Override
public <T, E extends Throwable> void close(RetryContext context,
RetryCallback<T, E> callback, Throwable throwable) {
log.info("onClose");
super.close(context, callback, throwable);
}
public <T, E extends Throwable> void onError(RetryContext context,
RetryCallback<T, E> callback, Throwable throwable) {
log.info("onError");
super.onError(context, callback, throwable);
public <T, E extends Throwable> boolean open(RetryContext context,
RetryCallback<T, E> callback) {
log.info("onOpen");
return super.open(context, callback);
}把listener設(shè)置到retryTemplate中
package org.example;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.retry.backoff.FixedBackOffPolicy;
import org.springframework.retry.policy.SimpleRetryPolicy;
import org.springframework.retry.support.RetryTemplate;
@Configuration
@Slf4j
public class AppConfig {
@Bean
public RetryTemplate retryTemplate() {
RetryTemplate retryTemplate = new RetryTemplate();
SimpleRetryPolicy retryPolicy = new SimpleRetryPolicy(); //設(shè)置重試策略
retryPolicy.setMaxAttempts(2);
retryTemplate.setRetryPolicy(retryPolicy);
FixedBackOffPolicy fixedBackOffPolicy = new FixedBackOffPolicy(); //設(shè)置退避策略
fixedBackOffPolicy.setBackOffPeriod(2000L);
retryTemplate.setBackOffPolicy(fixedBackOffPolicy);
retryTemplate.registerListener(new DefaultListenerSupport()); //設(shè)置retryListener
return retryTemplate;
}
}測(cè)試結(jié)果：
2021-01-08 10:48:05.663 INFO 20956 --- [ main] org.example.DefaultListenerSupport : onOpen
2021-01-08 10:48:05.663 INFO 20956 --- [ main] org.example.RetryTemplateService : do something...
2021-01-08 10:48:05.663 INFO 20956 --- [ main] org.example.DefaultListenerSupport : onError
2021-01-08 10:48:07.664 INFO 20956 --- [ main] org.example.RetryTemplateService : do something...
2021-01-08 10:48:07.664 INFO 20956 --- [ main] org.example.DefaultListenerSupport : onError
2021-01-08 10:48:07.664 INFO 20956 --- [ main] org.example.RetryTemplateTest : RecoveryCallback....
2021-01-08 10:48:07.664 INFO 20956 --- [ main] org.example.DefaultListenerSupport : onClose
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