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 Summary

    Modifier and Type
    Method
    Description
    Serializable
    checkpointInfo()
    The checkpointInfo method returns the current checkpoint data for this reader.
    void
    close()
    The close method marks the end of use of the ItemReader.
    void
    open(Serializable checkpoint)
    The open method prepares the reader to read items.
    Object
    readItem()
    The readItem method returns the next item for chunk processing.

  • Method Details

    • 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.