FlatFileItemWriter: Underlying CharsetEncoder not configurable

[Fiouz]

Hello,

While trying to write unsupported characters to a file (using the FlatFileItemWriter "encoding" property), I'm getting an UnmappableCharacterException:

ERROR [main] org.springframework.transaction.support.TransactionSynchronizationUtils | TransactionSynchronization.afterCompletion threw exception
org.springframework.batch.support.transaction.FlushFailedException: Could not write to output buffer
        at org.springframework.batch.support.transaction.TransactionAwareBufferedWriter$1.afterCompletion(TransactionAwareBufferedWriter.java:71)
        at org.springframework.transaction.support.TransactionSynchronizationUtils.invokeAfterCompletion(TransactionSynchronizationUtils.java:157)
        at org.springframework.transaction.support.AbstractPlatformTransactionManager.invokeAfterCompletion(AbstractPlatformTransactionManager.java:974)
        at org.springframework.transaction.support.AbstractPlatformTransactionManager.triggerAfterCompletion(AbstractPlatformTransactionManager.java:949)
        at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:777)
        at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:701)
        at org.springframework.batch.core.step.tasklet.TaskletStep$2.doInChunkContext(TaskletStep.java:304)
        at org.springframework.batch.core.scope.context.StepContextRepeatCallback.doInIteration(StepContextRepeatCallback.java:76)
        at org.springframework.batch.repeat.support.RepeatTemplate.getNextResult(RepeatTemplate.java:367)
        at org.springframework.batch.repeat.support.RepeatTemplate.executeInternal(RepeatTemplate.java:215)
        at org.springframework.batch.repeat.support.RepeatTemplate.iterate(RepeatTemplate.java:143)
        at org.springframework.batch.core.step.tasklet.TaskletStep.doExecute(TaskletStep.java:242)
        at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:198)
        at org.springframework.batch.core.job.AbstractJob.handleStep(AbstractJob.java:348)
        at org.springframework.batch.core.job.flow.FlowJob.access$0(FlowJob.java:1)
        at org.springframework.batch.core.job.flow.FlowJob$JobFlowExecutor.executeStep(FlowJob.java:135)
        at org.springframework.batch.core.job.flow.support.state.StepState.handle(StepState.java:60)
        at org.springframework.batch.core.job.flow.support.SimpleFlow.resume(SimpleFlow.java:144)
        at org.springframework.batch.core.job.flow.support.SimpleFlow.start(SimpleFlow.java:124)
        at org.springframework.batch.core.job.flow.FlowJob.doExecute(FlowJob.java:103)
        at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:250)
        at org.springframework.batch.core.launch.support.SimpleJobLauncher$1.run(SimpleJobLauncher.java:110)
        at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:49)
        at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:105)
        at org.springframework.batch.core.launch.support.CommandLineJobRunner.start(CommandLineJobRunner.java:291)
        at org.springframework.batch.core.launch.support.CommandLineJobRunner.main(CommandLineJobRunner.java:448)
        at xxx
Caused by: java.nio.charset.UnmappableCharacterException: Input length = 1
        at java.nio.charset.CoderResult.throwException(CoderResult.java:261)
        at sun.nio.cs.StreamEncoder$CharsetSE.implWrite(StreamEncoder.java:398)
        at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:136)
        at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:146)
        at java.io.Writer.write(Writer.java:126)
        at org.springframework.batch.support.transaction.TransactionAwareBufferedWriter$1.afterCompletion(TransactionAwareBufferedWriter.java:67)
        ... 26 more

So far, that is expected since my target encoding has no match for my data.
The problem is that I can't tell the writer not to fail when such event occurs.

Since FlatFileItemWriter (2.0.3) uses java.nio.channels.Channels.newWriter(WritableByteC hannel, String) instead of java.nio.channels.Channels.newWriter(WritableByteC hannel, CharsetEncoder, int) (in a private inner class), I can't find an easy way to configure the underlying CharsetEncoder in order to set the unmappableCharacterAction without duplicating lots of code.

Is there an easy way to achieve this?

Thanks