溫馨提示×
您好，登錄后才能下訂單哦！
點擊 登錄注冊 即表示同意《億速云用戶服務條款》
您好，登錄后才能下訂單哦！
怎么進行Spring-Retry的使用，針對這個問題，這篇文章詳細介紹了相對應的分析和解答，希望可以幫助更多想解決這個問題的小伙伴找到更簡單易行的方法。
在日常的一些場景中, 很多需要進行重試的操作.而spring-retry是spring提供的一個基于spring的重試框架，非常簡單好用.
<dependency> <groupId>org.springframework.retry</groupId> <artifactId>spring-retry</artifactId> <version>1.2.2.RELEASE</version> </dependency>
@Slf4j
public class RetryDemo {
public static boolean retryMethod(Integer param) {
int i = new Random().nextInt(param);
log.info("隨機生成的數:{}", i);
if (1 == i) {
log.info("為1,返回true.");
return true;
} else if (i < 1) {
log.info("小于1,拋出參數異常.");
throw new IllegalArgumentException("參數異常");
} else if (i > 1 && i < 10) {
log.info("大于1,小于10,拋出參數異常.");
return false;
} else {
//為其他
log.info("大于10,拋出自定義異常.");
throw new RemoteAccessException("大于10,拋出自定義異常");
}
}
}@Slf4j
public class SpringRetryTest {
/**
* 重試間隔時間ms,默認1000ms
*/
private long fixedPeriodTime = 1000L;
/**
* 最大重試次數,默認為3
*/
private int maxRetryTimes = 3;
/**
* 表示哪些異常需要重試
* key一定要為Throwable異常的子類 Class<? extends Throwable>
* value為true表示需要重試
*/
private Map<Class<? extends Throwable>, Boolean> exceptionMap = new HashMap<>();
@Test
public void test() {
// 1 添加異常的處理結果 true為需要重試 false為不需要重試
exceptionMap.put(RemoteAccessException.class, true);
// 2 構建重試模板實例
RetryTemplate retryTemplate = new RetryTemplate();
// 3 設置重試回退操作策略 設置重試間隔時間
FixedBackOffPolicy backOffPolicy = new FixedBackOffPolicy();
backOffPolicy.setBackOffPeriod(fixedPeriodTime);
// 4 設置重試策略 設置重試次數 設置異常處理結果
SimpleRetryPolicy retryPolicy = new SimpleRetryPolicy(maxRetryTimes, exceptionMap);
//5 重試模板添加重試策略 添加回退操作策略
retryTemplate.setRetryPolicy(retryPolicy);
retryTemplate.setBackOffPolicy(backOffPolicy);
// 6 調用方法
Boolean resp = retryTemplate.execute(
// RetryCallback 重試回調方法
retryContext -> {
boolean result = RetryDemo.retryMethod(110);
log.info("方法返回結果= {}", result);
return result;
},
// RecoveryCallback 異常回調方法
retryContext -> {
//
log.info("超過最大重試次數或者拋出了未定義的異常!!!");
return false;
}
);
log.info("接口返回結果 = {}",resp);
}
}
/*
// 查看結果
[main] INFO com.cf.demo.SpringRetry.SpringRetryTest - 超過最大重試次數或者拋出了未定義的異常!!!
[main] INFO com.cf.demo.SpringRetry.SpringRetryTest - 接口返回結果 = false
*/從代碼的書寫注解可以看到,RetryTemplate對象是Spring-Retry框架的重試執行者, 由它添加重試策略,回退操作策略等(注釋第五步).RetryTemplate執行重試方法(注釋第六步),通過execute方法, 傳入的參數是重試回調邏輯對象RetryCallback 和執行操作結束的恢復對象RecoveryCallback. 且可以切換添加的異常種類, 得知,只有添加過相應的異常,才會觸發重試操作,否則直接調用RecoveryCallback對象方法.
RetryTemplate的部分源碼:
/**
* Keep executing the callback until it either succeeds or the policy dictates that we
* stop, in which case the recovery callback will be executed.
*
* @see RetryOperations#execute(RetryCallback, RecoveryCallback)
* @param retryCallback the {@link RetryCallback}
* @param recoveryCallback the {@link RecoveryCallback}
* @throws TerminatedRetryException if the retry has been manually terminated by a
* listener.
*/
@Override
public final <T, E extends Throwable> T execute(RetryCallback<T, E> retryCallback,
RecoveryCallback<T> recoveryCallback) throws E {
return doExecute(retryCallback, recoveryCallback, null);
}RetryTemplate添加重試策略源碼:
/**
* Setter for {@link RetryPolicy}.
*
* @param retryPolicy the {@link RetryPolicy}
*/
public void setRetryPolicy(RetryPolicy retryPolicy) {
this.retryPolicy = retryPolicy;
}RetryPolicy接口的實現類:
AlwaysRetryPolicy：允許無限重試，直到成功，可能會導致死循環
CircuitBreakerRetryPolicy：有熔斷功能的重試策略，需設置3個參數openTimeout、resetTimeout和delegate
CompositeRetryPolicy：組合重試策略，有兩種組合方式，樂觀組合重試策略是指只要有一個策略允許即可以重試，
悲觀組合重試策略是指只要有一個策略不允許即可以重試，但不管哪種組合方式，組合中的每一個策略都會執行
ExceptionClassifierRetryPolicy：設置不同異常的重試策略，類似組合重試策略，區別在于這里只區分不同異常的重試
NeverRetryPolicy：只允許調用RetryCallback一次，不允許重試
SimpleRetryPolicy：固定次數重試策略，默認重試最大次數為3次，RetryTemplate默認使用的策略
TimeoutRetryPolicy：超時時間重試策略，默認超時時間為1秒，在指定的超時時間內允許重試
RetryTemplate添加回退策略源碼:
/**
* Setter for {@link BackOffPolicy}.
*
* @param backOffPolicy the {@link BackOffPolicy}
*/
public void setBackOffPolicy(BackOffPolicy backOffPolicy) {
this.backOffPolicy = backOffPolicy;
}BackOffPolicy的實現類:
ExponentialBackOffPolicy：指數退避策略，需設置參數sleeper、initialInterval、maxInterval和multiplier，initialInterval指定初始休眠時間，默認100毫秒，maxInterval指定最大休眠時間，默認30秒，multiplier指定乘數，即下一次休眠時間為當前休眠時間*multiplier
ExponentialRandomBackOffPolicy：隨機指數退避策略，引入隨機乘數可以實現隨機乘數回退
FixedBackOffPolicy：固定時間的退避策略，需設置參數sleeper和backOffPeriod，sleeper指定等待策略，默認是Thread.sleep，即線程休眠，backOffPeriod指定休眠時間，默認1秒
NoBackOffPolicy：無退避算法策略，每次重試時立即重試
UniformRandomBackOffPolicy：隨機時間退避策略，需設置sleeper、minBackOffPeriod和maxBackOffPeriod，該策略在[minBackOffPeriod,maxBackOffPeriod之間取一個隨機休眠時間，minBackOffPeriod默認500毫秒，maxBackOffPeriod默認1500毫秒
<dependency> <groupId>org.springframework.retry</groupId> <artifactId>spring-retry</artifactId> <version>1.2.2.RELEASE</version> </dependency> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjweaver</artifactId> <version>1.9.1</version> </dependency>
@Service
@Slf4j
public class SpringRetryDemo {
/**
* 重試所調用方法
* @return
*/
// delay=2000L表示延遲2秒 multiplier=2表示兩倍 即第一次重試2秒后,第二次重試4秒后,第三次重試8秒后
@Retryable(value = {RemoteAccessException.class}, maxAttempts = 3, backoff = @Backoff(delay = 2000L, multiplier = 2))
public boolean call(Integer param) {
return RetryDemo.retryMethod(param);
}
/**
* 超過最大重試次數或拋出沒有指定重試的異常
* @param e
* @param param
* @return
*/
@Recover
public boolean recover(Exception e, Integer param) {
log.info("請求參數為: ", param);
log.info("超過最大重試次數或拋出沒有指定重試的異常, e = {} ", e.getMessage());
return false;
}
}@SpringBootApplication
@EnableRetry
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}@RunWith(SpringRunner.class)
@SpringBootTest(classes = DemoApplication.class)
@Slf4j
public class DemoApplicationTests {
@Autowired
private SpringRetryDemo springRetryDemo;
@Test
public void testRetry() {
boolean result = springRetryDemo.call(110);
log.info("方法返回結果為: {}", result);
}
}
/* 運行結果:
隨機生成的數:77
大于10,拋出自定義異常.
隨機生成的數:23
大于10,拋出自定義異常.
隨機生成的數:82
大于10,拋出自定義異常.
請求參數為:
超過最大重試次數或拋出沒有指定重試的異常, e = 大于10,拋出自定義異常
方法返回結果為: false
*/注解說明:
@Enableretry注解，啟用重試功能(默認是否基于子類代理,默認是否, 即是基于Java接口代理)
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@EnableAspectJAutoProxy(proxyTargetClass = false)
@Import(RetryConfiguration.class)
@Documented
public @interface EnableRetry {
/**
* Indicate whether subclass-based (CGLIB) proxies are to be created as opposed
* to standard Java interface-based proxies. The default is {@code false}.
*
* @return whether to proxy or not to proxy the class
*/
boolean proxyTargetClass() default false;
}@Retryable注解, 標記的方法發生異常時會重試
value 指定發生的異常進行重試
include 與value一樣,默認為空,當exclude同時為空時,所有異常都重試
exclude 指定異常不重試,默認為空,當include同時為空,所有異常都重試
maxAttemps 重試次數,默認3
backoff 重試補充機制 默認是@Backoff()注解
@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).
* @return exception types to retry
*/
Class<? extends Throwable>[] include() default {};
/**
* Exception types that are not retryable. Defaults to empty (and if includes is also
* empty all exceptions are retried).
* @return exception types 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;
/**
* @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();
/**
* 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
* <pre class=code>
* {@code "@someBean.shouldRetry(#root)"}.
* </pre>
* @return the expression.
* @since 1.2
*/
String exceptionExpression() default "";
}@Backoff注解
delay 延遲多久后重試
multiplier 延遲的倍數
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Import(RetryConfiguration.class)
@Documented
public @interface Backoff {
/**
* Synonym for {@link #delay()}.
*
* @return the delay in milliseconds (default 1000)
*/
long value() default 1000;
/**
* 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 "";
/**
<<<<<<< HEAD
* An expression evaluating to the maximum wait (in milliseconds) between retries.
* If less than the {@link #delay()} then ignored.
=======
* An expression evaluating to 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.
>>>>>>> Fix @Backoff JavaDocs - maxDelay
* Overrides {@link #maxDelay()}
*
* @return the maximum delay between retries (default 0 = ignored)
* @since 1.2
*/
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)
* @since 1.2
*/
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;
}@Recover注解
當重試達到規定的次數后,被注解標記的方法將被調用, 可以在此方法中進行日志的記錄等操作.(該方法的入參類型,返回值類型需要和重試方法保持一致)
@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Import(RetryConfiguration.class)
@Documented
public @interface Recover {
}關于怎么進行Spring-Retry的使用問題的解答就分享到這里了，希望以上內容可以對大家有一定的幫助，如果你還有很多疑惑沒有解開，可以關注億速云行業資訊頻道了解更多相關知識。
免責聲明：本站發布的內容（圖片、視頻和文字）以原創、轉載和分享為主，文章觀點不代表本網站立場，如果涉及侵權請聯系站長郵箱：is@yisu.com進行舉報，并提供相關證據，一經查實，將立刻刪除涉嫌侵權內容。
