Package jakarta.batch.api.chunk

Interface ItemReader

  • All Known Implementing Classes:
    AbstractItemReader
    public interface ItemReader
    ItemReader defines the batch artifact that reads items for chunk processing.

    • Method Detail

      • open

        void open​(Serializable checkpoint)
   throws Exception
        The open method prepares the reader to read items. The input parameter represents the last checkpoint for this reader in a given job instance. The checkpoint data is defined by this reader and is provided by the checkpointInfo method. The checkpoint data provides the reader whatever information it needs to resume reading items upon restart. A checkpoint value of null is passed upon initial start.
        Parameters:
        checkpoint - specifies the last checkpoint
        Throws:
        Exception - is thrown for any errors.

      • close

        void close()
    throws Exception
        The close method marks the end of use of the ItemReader. The reader is free to do any cleanup necessary.
        Throws:
        Exception - is thrown for any errors.

      • readItem

        Object readItem()
         throws Exception
        The readItem method returns the next item for chunk processing. It returns null to indicate no more items, which also means the current chunk will be committed and the step will end.
        Returns:
        next item or null
        Throws:
        Exception - is thrown for any errors.

      • checkpointInfo

        Serializable checkpointInfo()
                     throws Exception
        The checkpointInfo method returns the current checkpoint data for this reader. It is called before a chunk checkpoint is committed.
        Returns:
        checkpoint data
        Throws:
        Exception - is thrown for any errors.