Spring Batch FlatFileItemWriter does not write data to a file

Question

I am new to Spring Batch application. I am trying to use FlatFileItemWriter to write the data into a file. Challenge is application is creating the file on a given path, but, now writing the actual content into it.

Following are details related to code:

List<String> dataFileList : This list contains the data that I want to write to a file

FlatFileItemWriter<String> writer = new FlatFileItemWriter<>();
writer.setResource(new FileSystemResource("C:\\Desktop\\test"));
writer.open(new ExecutionContext());
writer.setLineAggregator(new PassThroughLineAggregator<>());
writer.setAppendAllowed(true);
writer.write(dataFileList);
writer.close();

This is just generating the file at proper place but contents are not getting written into the file.

Am I missing something? Help is highly appreciated.

Thanks!

It seems we need to close the stream otherwise the content won't flush — Nghia Do, Jan 05 '18 at 12:56
Is `dataFileList` filled with data? because I tested your code with SB 4.0 and 2.2.6 and file is correctly filled with test data (`dataFileList` is filled with integer from 0 to 500000 converted to String) — Luca Basso Ricci, Jan 08 '18 at 08:41
Where are you running this code? Haven't you defined any Bean for it? — Nikhil Pareek, Jan 08 '18 at 11:28
I have a same problem... @Saurabh Deshpande, did you find a solution? — kozmo, Jan 31 '18 at 11:28

score 3 · Answer 1 · answered Jan 08 '18 at 11:34

This is not a proper way to use Spring Batch Writer and writer data. You need to declare bean of Writer first.

Define Job Bean
Define Step Bean
Use your Writer bean in Step

Have a look at following examples:

https://github.com/pkainulainen/spring-batch-examples/blob/master/spring-boot/src/main/java/net/petrikainulainen/springbatch/csv/in/CsvFileToDatabaseJobConfig.java

https://spring.io/guides/gs/batch-processing/

score 2 · Answer 2 · answered Jan 08 '18 at 06:28

You probably need to force a sync to disk. From the docs at https://docs.spring.io/spring-batch/trunk/apidocs/org/springframework/batch/item/file/FlatFileItemWriter.html,

setForceSync

public void setForceSync(boolean forceSync)

Flag to indicate that changes should be force-synced to disk on flush. Defaults to false, which means that even with a local disk changes could be lost if the OS crashes in between a write and a cache flush. Setting to true may result in slower performance for usage patterns involving many frequent writes.

Parameters:
    forceSync - the flag value to set

Spring Batch FlatFileItemWriter does not write data to a file

2 Answers2