Spring batch retrieving data from job context in the next steps reader

Question

Im new to spring batch and was just looking for some help passing a list between steps. In my step 1 writer I am adding a list to the ExecutionContext.

ExecutionContext stepContext = this.stepExecution.getExecutionContext();
stepContext.put("messageList", messages);

In my reader from step two I am getting the data back by doing:

JobExecution jobExecution = stepExecution.getJobExecution();
    ExecutionContext jobContext = jobExecution.getExecutionContext();
    this.messages=  jobContext.get("messageList");

This works and i get the list but the issue I am having is that I want to pass this list onto the processor but the read() method from the ItemReader loops continuously returning the list where as I only want to return the list once. As it is doing this the processor loops also. Is there a way I can pass the list to the reader in step two without the read() method doing this? Bellow is my message reader

public class MessageReader implements ItemReader<Object> {

private Object messages;
@Override
public Object read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException {

    return messages;
}
    @BeforeStep
public void retrieveSharedStepDate(StepExecution stepExecution){
    JobExecution jobExecution = stepExecution.getJobExecution();
    ExecutionContext jobContext = jobExecution.getExecutionContext();
    this.messages=  jobContext.get("messageList");
}

So basically what im trying to do is get my reader in step two to read the list that is produced from my writer in step one.

sadWal sadWal · Accepted Answer · 2016-08-10T14:51:40

I have managed to find the root cause of the issue. From ItemReader API

Reads a piece of input data and advance to the next one. Implementations must return null at the end of the input data set

My reader was never returning null so it was entering a infinite loop. To fix I changed it so once I had sent what data I wanted I return null.

Spring batch retrieving data from job context in the next steps reader

1 Answers