Package org.mycore.frontend.fileupload

Class MCRUploadHandler

java.lang.Object
org.mycore.common.processing.MCRAbstractProgressable
org.mycore.common.processing.MCRAbstractProcessable
org.mycore.frontend.fileupload.MCRUploadHandler
All Implemented Interfaces:
MCRListenableProgressable, MCRProcessable, MCRProgressable
Direct Known Subclasses:
MCRUploadHandlerIFS
public abstract class MCRUploadHandler extends MCRAbstractProcessable
This class does the server-side of uploading files from a client browser, which runs the upload applet. This is an abstract base class that must be subclassed to implement the storage of files at the server side for miless, MyCoRe or other usages of the upload framework. Every instance of MCRUploadHandler handles one singe upload session with the applet.
Version:
$Revision$ $Date$
Author:
Harald Richter, Frank Lützenkirchen
See Also:

  • Field Details

    • uploadID

      protected String uploadID
      The unique ID of this upload session *

    • url

      protected String url
      The url where to go after upload is finished. *

  • Constructor Details

    • MCRUploadHandler

      protected MCRUploadHandler()
      Creates a new upload handler and registers it at the handler manager *

  • Method Details

    • getID

      public final String getID()
      Returns the unique ID of this upload session *

    • getRedirectURL

      public String getRedirectURL()
      Returns the url where to go after upload is finished *

    • startUpload

      public void startUpload(int numberOfFiles)
      Starts the upload session.
      Parameters:
      numberOfFiles - the number of files that will be uploaded

    • incrementNumFiles

      public int incrementNumFiles()
      Increments the uploaded number of files. Use this method with care! In general a fixed number of files to upload should be set with startUpload(int).
      Returns:
      the new number of files to upload

    • decrementNumFiles

      public int decrementNumFiles()
      Decrements the uploaded number of files. Use this method with care! In general a fixed number of files to upload should be set with startUpload(int).
      Returns:
      the new number of files to upload

    • getNumFiles

      public int getNumFiles()
      Returns the number of files which will be uploaded
      Returns:
      number of files to upload

    • acceptFile

      public boolean acceptFile(String path, String checksum, long length) throws Exception
      This method is called to ask if this file should be uploaded and will be accepted by the server. The default implementation always returns true (always upload file), but subclasses should overwrite this method to decide whether the file's content must be uploaded. Decision can be based on the MD5 checksum, so unchanged files do not have to be uploaded again.
      Parameters:
      path - the path and filename of the file
      checksum - the MD5 checksum computed at the client side
      length - the length of the file in bytes (file size)
      Returns:
      true, if the file should be uploaded, false if the file should be skipped
      Throws:
      Exception

    • receiveFile

      public abstract long receiveFile(String path, InputStream in, long length, String md5) throws Exception
      This method is called so that the UploadHandler subclass can store the file on the server side. When the UploadHandler could read less than length bytes from the InputStream at the time the InputStream has no data any more, the user at the remote side canceled upload during file transfer. The UploadHandler then can decide to delete the file, but must return the number of bytes stored. The UploadHandler can also compare the MD5 checksum calculated at the client side with its own checksum, to detect magical transfer errors. This method requires a database transaction.
      Parameters:
      path - the path and filename of the file
      in - the inputstream to read the content of the file from
      length - the total file size as number of bytes. This may be 0, meaning that the file is empty or the file size is not known.
      md5 - the md5 checksum calculated at the client side. This may be null, meaning that the md5 checksum is not known.
      Returns:
      the number of bytes that have been stored.
      Throws:
      Exception

    • finishUpload

      public abstract void finishUpload() throws Exception
      After finishing uploading all files, this method is called so that the UploadHandler subclass can finish work and commit all saved files.
      Throws:
      Exception

    • cancelUpload

      public void cancelUpload() throws Exception
      This method is called so that the UploadHandler subclass can finish or cancel work. The implementation is optional, by default finishUpload() is called
      Throws:
      Exception

    • unregister

      public void unregister()
      Automatically unregister this upload handler from the UploadHandlerManager.