Spring Batch FlatFileItemReader在读取的所有项目/行中填充字段值

Question

I am reading a flat file using spring batch FlatFileItemReader .

I have a requestId field which i need to populate with a unique value for all records read from the flat file. eg: When i read file1. I want to set the requestId to 1 for all Item objects created at requestId field. For file2, i need to set requestId to 2.

my requestId is uniquely generated by a separate class.

How can I achieve this using spring batch?

Answer 1

there are some possible solutions

use an ResourceAware Item

public class MyItem implements ResourceAware {

    private Resource resource;

    public String getId() {
        return createIdFromResource(resource);
    }

    private String createIdFromResource(final Resource resource) {
        // create your ID here
        return resource.getFilename();
    }

    @Override
    public void setResource(final Resource resource) {
        this.resource = resource;
    }
}

use an Listener (here with interfaces, less verbose use of annotations is possible too)

public class TestListener implements StepExecutionListener, ItemReadListener<String> {
    private StepExecution stepExecution;
    private static final String CURRENT_ID = "currentId";

    @Override
    public void beforeStep(final StepExecution stepExecution) {
        this.stepExecution = stepExecution;
    }

    @Override
    public ExitStatus afterStep(final StepExecution stepExecution) {
        return null;
    }

    @Override
    public void beforeRead() {
    }

    @Override
    public void afterRead(final String item) {
        String currentId = null;
        if (stepExecution.getExecutionContext().containsKey(CURRENT_ID)) {
            currentId = stepExecution.getExecutionContext().getString(CURRENT_ID);
        } else {
            String fileName = stepExecution.getExecutionContext().getString("fileName");
            // ... create ID from FileName
            currentId = fileName + "foo";
            stepExecution.getExecutionContext().put(CURRENT_ID, currentId);
        }
    }

    @Override
    public void onReadError(final Exception ex) {
    }
}

in the above example the current fileName is avavailable in the stepExecutionContext, it might be you have to pull it from jobParameters and extract the filename

String paramValue = stepExecution.getJobExecution().getJobParameters().getString("paramName");
// extract fileName from paramValue