CODEWITHSUNDEEP
javaspringparsingspring-batch
TPPZ
TPPZ

Reputation: 4891

ItemReader returning a FlatFileItemReader containing entire lines as strings

Using Spring Batch I am trying to get every line of an input file as a String giving it to the ItemProcessor without any "CSV parsing" in the ItemReader.

I came out with a configuration Java class (using @Configuration and @EnableBatchProcessing) containing the following reader() method which is making the next ItemProcessor to throw a ClassCastException though.

This ItemReader should read an input file and pass to the ItemProcessor every line of the input file as a String.

@Bean
public ItemReader<String> reader() {

    FlatFileItemReader<String> reader = new FlatFileItemReader<>();
    reader.setResource(new ClassPathResource("data-to-process.txt"));
    reader.setLineMapper(new DefaultLineMapper() {{
        setLineTokenizer(new DelimitedLineTokenizer());
        setFieldSetMapper(new PassThroughFieldSetMapper());
    }});
    return reader;
}

When running the previous code I am getting an exception in the ItemProcessor which is expecting a String from the reader():

    java.lang.ClassCastException: org.springframework.batch.item.file.transform.DefaultFieldSet cannot be cast to java.lang.String

The custom ItemProcessor I wrote is defined as:

    public class MyOwnCustomItemProcessor implements ItemProcessor<String, MyOwnCustomBusinessBean> {

I believe I should use this PassThroughFieldSetMapper in the ItemReader and I would not like to use any kind of tokenizer. According to the documentation I think I must use it and I can not avoid it, but I am keeping getting exceptions thrown.

How can I "transfer" every input line directly as a String to an ItemProcessor e.g. ?

Upvotes: 5

Views: 9344

Answers (2)

TPPZ
TPPZ

Reputation: 4891

I am adding also a workaround I found in the meanwhile (using FieldSet as a input parameter of the ItemReader and the ItemProcessor), even if @bellabax provided a better solution.

Check how I used the objects of type FieldSet.

The ItemReader:

@Bean
public ItemReader<FieldSet> reader() {

    FlatFileItemReader<FieldSet> reader = new FlatFileItemReader<>();
    reader.setResource(new ClassPathResource("data-to-process.txt"));
    reader.setLineMapper(new DefaultLineMapper() {{
        setLineTokenizer(new DelimitedLineTokenizer());
        setFieldSetMapper(new PassThroughFieldSetMapper() {{

        }});

    }});
    return reader;
}

The ItemProcessor in the Spring Batch Configuration class:

@Bean
public ItemProcessor<FieldSet, MyOwnCustomBusinessBean> processor() {

    return new MyOwnCustomItemProcessor();
}

The ItemProcessor:

public class MyOwnCustomItemProcessor implements ItemProcessor<FieldSet, MyOwnCustomBusinessBean> {

    @Override
    public MyOwnCustomBusinessBean process(FieldSet originalInputLineFromInputFile) throws Exception {

        String originalInputLine = originalInputLineFromInputFile.getValues()[0];

        [...]

Upvotes: 0

Luca Basso Ricci
Luca Basso Ricci

Reputation: 18413

Use PassThroughLineMapper if available else 

public class PassThroughLineMapper implements LineMapper<String> {
  @Override
  public String mapLine(String line, int lineNumber) throws Exception {
    return line;
  }
}

Upvotes: 7

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