Spring Batch - 要读取的文件不可用答案

【问题标题】：Spring Batch - File to be read is not availableSpring Batch - 要读取的文件不可用
【发布时间】：2016-08-04 20:32:33
【问题描述】：

我有一个 Spring 批处理作业，第一步是读取文件并写入数据库。如果该文件不存在，我希望系统等待 x 分钟，然后重试该步骤最多 y 次尝试。我怎样才能做到这一点？

详情

ItemReader如下：

 @Bean
    public ItemReader<Car> reader(LineMapper<Car> lineMapper, File file) {
        FlatFileItemReader<Car> flatFileItemReader = new FlatFileItemReader<Car>();
        flatFileItemReader.setResource(new FileSystemResource(file));
        final int NUMBER_OF_HEADER_LINES = 1;
        flatFileItemReader.setLinesToSkip(NUMBER_OF_HEADER_LINES);
        flatFileItemReader.setLineMapper(lineMapper);
        return flatFileItemReader;
    }

目前，如果file不存在，则抛出以下异常，作业失败。

2016-08-05 09:30:10.277 ERROR 7668 --- [           main] o.s.batch.core.step.AbstractStep         : Encountered an error executing step stepLoadFile in job testJob

org.springframework.batch.item.ItemStreamException: Failed to initialize the reader
    at org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader.open(AbstractItemCountingItemStreamItemReader.java:147) ~[spring-batch-infrastructure-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.batch.item.support.CompositeItemStream.open(CompositeItemStream.java:96) ~[spring-batch-infrastructure-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.batch.core.step.tasklet.TaskletStep.open(TaskletStep.java:310) ~[spring-batch-core-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:197) ~[spring-batch-core-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.batch.core.job.SimpleStepHandler.handleStep(SimpleStepHandler.java:148) [spring-batch-core-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.batch.core.job.AbstractJob.handleStep(AbstractJob.java:392) [spring-batch-core-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.batch.core.job.SimpleJob.doExecute(SimpleJob.java:135) [spring-batch-core-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:306) [spring-batch-core-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.batch.core.launch.support.SimpleJobLauncher$1.run(SimpleJobLauncher.java:135) [spring-batch-core-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50) [spring-core-4.2.4.RELEASE.jar:4.2.4.RELEASE]
    at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:128) [spring-batch-core-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_91]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_91]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_91]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_91]
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:302) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
    at org.springframework.batch.core.configuration.annotation.SimpleBatchConfiguration$PassthruAdvice.invoke(SimpleBatchConfiguration.java:127) [spring-batch-core-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
    at com.sun.proxy.$Proxy78.run(Unknown Source) [na:na]
    at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.execute(JobLauncherCommandLineRunner.java:215) [spring-boot-autoconfigure-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.executeLocalJobs(JobLauncherCommandLineRunner.java:232) [spring-boot-autoconfigure-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.launchJobFromProperties(JobLauncherCommandLineRunner.java:124) [spring-boot-autoconfigure-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.run(JobLauncherCommandLineRunner.java:118) [spring-boot-autoconfigure-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:804) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:788) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.afterRefresh(SpringApplication.java:775) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.doRun(SpringApplication.java:366) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:305) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1124) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1113) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
    at com.myorg.LoadApplication.main(LoadApplication.java:15) [bin/:na]
Caused by: java.lang.IllegalStateException: Input resource must exist (reader is in 'strict' mode): file [C:\test\TestData.csv]
    at org.springframework.batch.item.file.FlatFileItemReader.doOpen(FlatFileItemReader.java:251) ~[spring-batch-infrastructure-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    at org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader.open(AbstractItemCountingItemStreamItemReader.java:144) ~[spring-batch-infrastructure-3.0.6.RELEASE.jar:3.0.6.RELEASE]
    ... 33 common frames omitted

com.myorg.LoadApplication 代码启动批处理应用程序并且是：

@SpringBootApplication
public class LoadApplication {

    public static void main(String[] args) {
        SpringApplication.run(LoadApplication.class, args);
    }

}

更新

在阅读了 dimitrisli 的答案后，我在 @Configuration 类中尝试了这个（注意：我还在配置类中添加了 @EnableRetry）：

@Bean
public ItemReader<Test> reader(LineMapper<Test> lineMapper, ApplicationProperties properties) {
    FlatFileItemReader<Test> flatFileItemReader = new FlatFileItemReader<Test>() {
        @Override
        @Retryable(value = {ItemStreamException.class}, maxAttempts=5)
        public void open(ExecutionContext executionContext) throws ItemStreamException {
            super.open(executionContext);
        }

        @Override
        @Retryable(maxAttempts=5)
        public Holding read() throws UnexpectedInputException, ParseException, Exception {
            return super.read();
        }

    };
    flatFileItemReader.setResource(new FileSystemResource(properties.getLoadFile()));
    flatFileItemReader.setLineMapper(lineMapper);
    return flatFileItemReader;
}

ItemStreamException 被抛出并且应用程序退出而不重试。我怎样才能让它重试？

【问题讨论】：

通过将 dimitrisli 的答案应用于 ItemReader（上面更新中显示的代码），我终于可以让它工作了。由于 spring-boot-starter-batch 版本 1.3.1.RELEASE 中的错误 (?)，应用程序在没有重试的情况下退出。移至 1.4.0.RELEASE 后，重试按预期工作。将 dimitrisli 的答案标记为正确，因为它回答了我原来的问题。

标签： spring spring-batch spring-retry

【解决方案1】：

通过使用Spring Retry，来自Spring Batch 的独立衍生项目：假设可能抛出异常，您希望从中恢复并重试5 次，是ItemStreamException，那么您将不得不装饰您的可能引发此异常的方法为：

@Retryable(value = {ItemStreamException.class}, maxAttempts = 5)
public void myMethod() {
   //..
}

【讨论】：

问题是我的代码没有抛出这个异常。 Spring Batch 抛出异常。我已经向 OP 添加了完整的堆栈跟踪。查看堆栈跟踪，我想我可以添加 @Retryable main 方法（这是运行 Spring Boot 批处理应用程序的位置）。这是您的建议还是有更好（更有针对性）的地方放置此注释？

【解决方案2】：

您应该使用 spring-retry 。

RetryTemplate 与TimeoutRetryPolicy 结合使用将允许您编写所需的功能。

您需要在配置类中添加@EnableRetry，在方法中添加@Retryable。

是否需要先实例化 ItemReader 才能启动应用程序？如果不是，您应该只创建 bean 并在上下文刷新后让另一个方法对其进行初始化。

【讨论】：

我已阅读该链接，但我不清楚它如何用于/配置用于我描述的场景。您能否提供一个代码示例，说明您将如何完成此操作？