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服务器之家 - 编程语言 - JAVA教程 - Spring的异常重试框架Spring Retry简单配置操作

Spring的异常重试框架Spring Retry简单配置操作

2020-09-18 13:15狂丰 JAVA教程

这篇文章主要介绍了Spring的异常重试框架Spring Retry简单配置操作,具有很好的参考价值,希望对大家有所帮助。一起跟随小编过来看看吧

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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:

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<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

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@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。

以上这篇Spring的异常重试框架Spring Retry简单配置操作就是小编分享给大家的全部内容了,希望能给大家一个参考,也希望大家多多支持服务器之家。

原文链接:https://blog.csdn.net/fz13768884254/article/details/83176459

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