public String getTileDirectoryPath(WMTTile tile) {
   return WMTTileImageReadWriter.pathCombine(baseDir, tile.getReleatedSourceId());
 }
 /**
  * Fetch the name of the file for the given tile
  *
  * @param tile
  * @param filetype
  * @return
  */
 @Override
 public String getTileFileName(Tile tile, String filetype) {
   return WMTTileImageReadWriter.pathCombine(
       getTileDirectoryPath(tile), tile.getPosition() + "." + filetype); // $NON-NLS-1$
 }
  public WMTTileImageReadWriter(String baseDir) {
    super(null, baseDir);

    this.baseDir = WMTTileImageReadWriter.pathCombine(baseDir, "wmt-tile-cache"); // $NON-NLS-1$
  }