Unfound resource for FlatFileItemReader after moving the file

Question

I am using Spring Batch to read from a CSV file and write the lines on the screen. My job is composed of 3 parts: Part 1 : Verify if the CSV file exists in some INPUT directory on my disk, if it returns TRUE the file will be moved to another directory called PROD. Part 2 : Extract data from the CSV file using FlatFileItemReader. Part 3 : Write the all the items to the screen.

The problem is the FlatFileItemReader throws org.springframework.batch.item.ItemStreamException: Failed to initialize the reader caused by java.lang.IllegalArgumentException: Input resource must be set

Here is my code:

@Bean
public FlatFileItemReader<UniversInvestissement> reader() {
    FlatFileItemReader<UniversInvestissement> reader = new FlatFileItemReader<>();
    File csvFile = new File("C://INPUT/data.csv");
    Resource resource = resourceLoader.getResource("file:" + csvFile.getAbsolutePath());
    reader.setLinesToSkip(1);
    reader.setResource(resource);
    DefaultLineMapper lineMapper = new DefaultLineMapper();

    DelimitedLineTokenizer tokenizer = new DelimitedLineTokenizer();
    tokenizer.setNames(new String[]{"COL1", "COL2", "COL3", "COL4"});
    tokenizer.setDelimiter(";");

    FieldSetMapper fieldSetMapper = new UniversInvestissementFieldSetMapper();
    lineMapper.setLineTokenizer(tokenizer);
    lineMapper.setFieldSetMapper(fieldSetMapper);

    reader.setLineMapper(lineMapper);

    reader.setEncoding("Cp1252");
    return reader;
}

@Bean
public UniversInvestissementWriter writer() {
    return new UniversInvestissementWriter();
}

@Bean
public UniversInvestissementProcessor processor() {
    return new UniversInvestissementProcessor();
}

@Bean
public Step extractData() {
    return steps.get("extractData")
            .<UniversInvestissement, UniversInvestissementProcessorResult>chunk(1)
            .reader(reader())
            .processor(processor())
            .writer(writer())
            .build();
}

Actually the problem is that when the FlatFileItemReader is initialized it can't find the CSV file as a resource ! Is there a way to postpone the resource assignment and avoid this exception ?

Answer 1

you Can use reader.setStrict(false); if you set strict mode to false the reader will Not throw an exception on. You might have to use @StepScope to make reader lazy. I am using same setup and it's working fine for me , Hope this helps you

Answer 2

I think that problem in your resourceLoader, because such exception thrown by non-null assertion of resource instance. So you resourceLoader return null value.

Try to use FileSystemResource and without any resource loaders. For example:

reader.setResource(new FileSystemResource(csvFile));

Answer 3

Verify if the CSV file exists in some INPUT directory on my disk, if it returns TRUE the file will be moved to another directory called PROD

This problem can easly be solved using a JobExecutionDecider

class Checker implements JobExecutionDecider {
  FlowExecutionStatus decide(...) {
    if(<file not found in INPUT/ dir>) {
      return FlowExecutionStatus.STOPPED;
    }
    if(!<copy file from INPUT/ to PROD/ works>) {
      return FlowExecutionStatus.FAILED;
    }
    return FlowExecutionStatus.COMPLETED;
  }
}

Of course, extractData() must be changed to insert use of programmatic flow decision (check here for a simple example)