Question

目前，我使用jobParameters来获取FlatFileItemReader和FlatFileItemWriter的文件名。测试我的批次是可以的，但我的目标是读取某个目录中的文件（此目录中只有此文件），文件名可能会更改。输出文件名应取决于输入文件名。

因此，我考虑在我的工作中添加一个新步骤，此步骤将通过搜索好目录并在其中查找文件来设置输出和输入文件名。我从Spring Doc中读取Passing Data to Future Steps，从SO中读取this thread，但我无法使其正常工作，文件总是＆＃34; null＆＃34;。

首先，我已经定义了以下Tasklet

public class SettingFilenamesTasklet implements Tasklet {

    private StepExecution stepExecution;

    @Override
    public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) throws Exception {
        // TODO Search folder and set real filenames
        String inputFilename = "D:/TestInputFolder/dataFile.csv";
        String outputFilename = "D:/TestOutputFolder/dataFile-processed.csv";
        ExecutionContext stepContext = stepExecution.getExecutionContext();
        stepContext.put("inputFile", inputFilename);
        stepContext.put("outputFile", outputFilename);
        return RepeatStatus.FINISHED;
    }

    @BeforeStep
    public void saveStepExecution(StepExecution stepExec) {
        stepExecution = stepExec;
    }
}

然后，我添加了promotionListener bean

@Bean
public ExecutionContextPromotionListener promotionListener() {
    ExecutionContextPromotionListener listener = new ExecutionContextPromotionListener();
    listener.setKeys(new String[]{
            "inputFile", "outputFile"
    });
    return listener;
}

我在FlatFileItemWriter定义中通过jobExecutionContext更改了jobParameters（我没有将一行更改为代码本身）

@Bean
@StepScope
public FlatFileItemWriter<RedevableCRE> flatFileWriter(@Value("#{jobExecutionContext[outputFile]}") String outputFile) {
    FlatFileItemWriter<Employee> flatWriter = new FlatFileItemWriter<Employee>();
    FileSystemResource isr;
    isr = new FileSystemResource(new File(outputFile));
    flatWriter.setResource(isr);
    DelimitedLineAggregator<RedevableCRE> aggregator = new DelimitedLineAggregator<RedevableCRE>();
    aggregator.setDelimiter(";");
    BeanWrapperFieldExtractor<RedevableCRE> beanWrapper = new BeanWrapperFieldExtractor<RedevableCRE>();
    beanWrapper.setNames(new String[]{
        "id", "firstName", "lastName", "phone", "address"
    });
    aggregator.setFieldExtractor(beanWrapper);
    flatWriter.setLineAggregator(aggregator);
    flatWriter.setEncoding("ISO-8859-1");
    return flatWriter;
}

我添加了我的Tasklet bean

@Bean
public SettingFilenamesTasklet settingFilenames() {
    return new SettingFilenamesTasklet();
}

我创建了一个新的步骤来添加我的工作声明

@Bean
public Step stepSettings(StepBuilderFactory stepBuilderFactory, SettingFilenamesTasklet tasklet, ExecutionContextPromotionListener listener) {
    return stepBuilderFactory.get("stepSettings").tasklet(tasklet).listener(listener).build();
}

现在，FlatFileItemReader仍然使用jobParameters值，我想让我的FlatFileItemWriter先工作。我收到以下错误：

[...]    
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.file.FlatFileItemWriter]: Factory method 'flatFileWriter' threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:591)
    ... 87 common frames omitted
Caused by: java.lang.NullPointerException: null
    at java.io.File.<init>(Unknown Source)
    at batchTest.BatchConfiguration.flatFileWriter(BatchConfiguration.java:165)
    at batchTest.BatchConfiguration$$EnhancerBySpringCGLIB$$5d415889.CGLIB$flatFileWriter$1(<generated>)
    at batchTest.BatchConfiguration$$EnhancerBySpringCGLIB$$5d415889$$FastClassBySpringCGLIB$$969a8527.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:312)
    at batchTest.BatchConfiguration$$EnhancerBySpringCGLIB$$5d415889.flatFileWriter(<generated>)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162)
    ... 88 common frames omitted

我试图用@JobScope替换@StepScope注释;将我的参数直接放入jobExecutionContext（+ JobExecutionListener）而不是使用StepContext + promotionListener ......没有任何作用。当我尝试创建FlatFileItemWriter时，资源文件始终为null。

我错过了什么？

感谢您的帮助。

Answer 1

在tasklet中，您可以使用ChunkContext，因此您不需要@BeforeStep，您可以将其删除（在我的配置中，根本不会调用它，并且当您将其视为一个操作时步骤没有多大意义，但我没有看到NPE所以猜测那部分工作）。我们用两种方法之一解决了这个问题：

您可以使用ExecutionContext

chunkContext.getStepContext().getStepExecution().getJobExecution().getExecutionContext().put("inputFile", inputFilename);

您可以将ExecutionContextPromotionListener添加到您的tasklet步骤，然后执行chunkContext.getStepContext().getStepExecution().getExecutionContext().put("inputFile", inputFilename);

从tasklet步骤向作业上下文添加参数，并在Spring Batch的后续步骤中使用

1 个答案: