Class DownloadAction

All Implemented Interfaces:
Serializable

public abstract class DownloadAction extends BaseAction
This is an abstract base class that minimizes the amount of special coding that needs to be written to download a file. All that is required to use this class is to extend it and implement the getStreamInfo() method so that it returns the relevant information for the file (or other stream) to be downloaded. Optionally, the getBufferSize() method may be overridden to customize the size of the buffer used to transfer the file.
Since:
Struts 1.2.6
See Also:
  • Field Details

    • DEFAULT_BUFFER_SIZE

      protected static final int DEFAULT_BUFFER_SIZE
      If the getBufferSize() method is not overridden, this is the buffer size that will be used to transfer the data to the servlet output stream.
      See Also:
  • Constructor Details

    • DownloadAction

      public DownloadAction()
  • Method Details

    • getStreamInfo

      protected abstract DownloadAction.StreamInfo getStreamInfo(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
      Returns the information on the file, or other stream, to be downloaded by this action. This method must be implemented by an extending class.
      Parameters:
      mapping - The ActionMapping used to select this instance.
      form - The optional ActionForm bean for this request (if any).
      request - The HTTP request we are processing.
      response - The HTTP response we are creating.
      Returns:
      The information for the file to be downloaded.
      Throws:
      Exception - if an exception occurs.
    • getBufferSize

      protected int getBufferSize()
      Returns the size of the buffer to be used in transferring the data to the servlet output stream. This method may be overridden by an extending class in order to customize the buffer size.
      Returns:
      The size of the transfer buffer, in bytes.
    • execute

      public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
      Process the specified HTTP request, and create the corresponding HTTP response (or forward to another web component that will create it). Return an ActionForward instance describing where and how control should be forwarded, or null if the response has already been completed.
      Overrides:
      execute in class Action
      Parameters:
      mapping - The ActionMapping used to select this instance.
      form - The optional ActionForm bean for this request (if any).
      request - The HTTP request we are processing.
      response - The HTTP response we are creating.
      Returns:
      The forward to which control should be transferred, or null if the response has been completed.
      Throws:
      Exception - if an exception occurs.
    • copy

      public int copy(InputStream input, OutputStream output) throws IOException
      Copy bytes from an InputStream to an OutputStream.
      Parameters:
      input - The InputStream to read from.
      output - The OutputStream to write to.
      Returns:
      the number of bytes copied
      Throws:
      IOException - In case of an I/O problem