Spring的异常重试框架Spring Retry简单配置操作

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/*
* Copyright 2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*   http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package org.springframework.retry.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
* Annotation for a method invocation that is retryable.
*
* @author Dave Syer
* @author Artem Bilan
* @author Gary Russell
* @since 1.1
*
*/
@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 "";

}

下面就 Retryable的简单配置做一个讲解：

首先引入maven依赖：

<dependency>
     <groupId>org.springframework.retry</groupId>
     <artifactId>spring-retry</artifactId>
     <version>RELEASE</version>
   </dependency>

然后在方法上配置注解@Retryable

@Override
@SuppressWarnings("Duplicates")
@Retryable(value = {RemoteAccessException.class}, maxAttempts = 3, backoff = @Backoff(delay = 3000l, multiplier = 0))
public boolean customSendText(String openid, String content) throws RemoteAccessException {
 String replyString = "{\n" +
     "\"touser\":" + openid + ",\n" +
     "\"msgtype\":\"text\",\n" +
     "\"text\":\n" +
     "{\n" +
     "\"content\":" + content + "\n" +
     "}\n" +
     "}";
 try {
   logger.info("wx:customSend=request:{}", replyString.toString());
   HttpsClient httpClient = HttpsClient.getAsyncHttpClient();
   String url = Constant.WX_CUSTOM_SEND;
   String token = wxAccessokenService.getAccessToken();
   url = url.replace("ACCESS_TOKEN", token);
   logger.info("wx:customSend=url:{}", url);
   String string = httpClient.doPost(url, replyString);
   logger.info("wx:customSend=response:{}", string);
   if (StringUtils.isEmpty(string)) throw new RemoteAccessException("发送消息异常");
   JSONObject jsonTexts = (JSONObject) JSON.parse(string);
   if (jsonTexts.get("errcode") != null) {
     String errcode = jsonTexts.get("errcode").toString();
     if (errcode == null) {
       throw new RemoteAccessException("发送消息异常");
     }
     if (Integer.parseInt(errcode) == 0) {
       return true;
     } else {
       throw new RemoteAccessException("发送消息异常");
     }
   } else {
     throw new RemoteAccessException("发送消息异常");
   }
 } catch (Exception e) {
   logger.error("wz:customSend:{}", ExceptionUtils.getStackTrace(e));
   throw new RemoteAccessException("发送消息异常");
 }
}

注解内容介绍：

@Retryable注解

被注解的方法发生异常时会重试

value：指定发生的异常进行重试

include：和value一样，默认空，当exclude也为空时，所有异常都重试

exclude：指定异常不重试，默认空，当include也为空时，所有异常都重试

maxAttemps：重试次数，默认3

backoff：重试补偿机制，默认没有

@Backoff注解

delay:指定延迟后重试

multiplier:指定延迟的倍数，比如delay=5000l,multiplier=2时，第一次重试为5秒后，第二次为10秒，第三次为20秒

注意：

1、使用了@Retryable的方法不能在本类被调用，不然重试机制不会生效。也就是要标记为@Service，然后在其它类使用@Autowired注入或者@Bean去实例才能生效。

2、使用了@Retryable的方法里面不能使用try...catch包裹，要在发放上抛出异常，不然不会触发。

3、在重试期间这个方法是同步的，如果使用类似Spring Cloud这种框架的熔断机制时，可以结合重试机制来重试后返回结果。

4、Spring Retry不仅能注入方式去实现，还可以通过API的方式实现，类似熔断处理的机制就基于API方式实现会比较宽松。

来源：https://blog.csdn.net/fz13768884254/article/details/83176459