Spring的異常重試框架Spring Retry簡單配置操作
阿新 • • 發佈:2020-09-18
相關api見:點選進入
/* * 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的簡單配置做一個講解:
首先引入maven依賴:
<dependency> <groupId>org.springframework.retry</groupId> <artifactId>spring-retry</artifactId> <version>RELEASE</version> </dependency>
然後在方法上配置註解@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("傳送訊息異常"); JSONObject jsonTexts = (JSONObject) JSON.parse(string); if (jsonTexts.get("errcode") != null) { String errcode = jsonTexts.get("errcode").toString(); if (errcode == null) { throw new RemoteAccessException("傳送訊息異常"); } if (Integer.parseInt(errcode) == 0) { return true; } else { throw new RemoteAccessException("傳送訊息異常"); } } else { throw new RemoteAccessException("傳送訊息異常"); } } catch (Exception e) { logger.error("wz:customSend:{}",ExceptionUtils.getStackTrace(e)); throw new RemoteAccessException("傳送訊息異常"); } }
註解內容介紹:
@Retryable註解
被註解的方法發生異常時會重試
value:指定發生的異常進行重試
include:和value一樣,預設空,當exclude也為空時,所有異常都重試
exclude:指定異常不重試,預設空,當include也為空時,所有異常都重試
maxAttemps:重試次數,預設3
backoff:重試補償機制,預設沒有
@Backoff註解
delay:指定延遲後重試
multiplier:指定延遲的倍數,比如delay=5000l,multiplier=2時,第一次重試為5秒後,第二次為10秒,第三次為20秒
注意:
1、使用了@Retryable的方法不能在本類被呼叫,不然重試機制不會生效。也就是要標記為@Service,然後在其它類使用@Autowired注入或者@Bean去例項才能生效。
2、使用了@Retryable的方法裡面不能使用try...catch包裹,要在發放上丟擲異常,不然不會觸發。
3、在重試期間這個方法是同步的,如果使用類似Spring Cloud這種框架的熔斷機制時,可以結合重試機制來重試後返回結果。
4、Spring Retry不僅能注入方式去實現,還可以通過API的方式實現,類似熔斷處理的機制就基於API方式實現會比較寬鬆。
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