FlavorMapBugExhibit.java

package com.sieuferd.harness;

import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.SystemFlavorMap;
import java.awt.datatransfer.Transferable;
import java.io.InputStream;

public final class FlavorMapBugExhibit {
  public static final boolean ENABLE_WORKAROUND = false;

  private FlavorMapBugExhibit() { }

  /* To test, open Microsoft Excel for Mac 2011, select a few cells, and invoke "Copy" to copy the
  cells to the clipboard. Then run this class. When ENABLE_WORKAROUND is false, an
  UnsupportedFlavorException will be thrown. The bug does not exist on Windows (tested with
  Excel 2013). */
  public static void main(String args[]) throws Exception {
    DataFlavor dataFlavor = registerExcelDataFlavor();
    Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
    Transferable transferable = clipboard.getContents(null);

    try (InputStream is = (InputStream) transferable.getTransferData(dataFlavor)) {
      // Should print 208, 207.
      System.out.println(is.read());
      System.out.println(is.read());
    }
  }

  private static DataFlavor registerExcelDataFlavor() throws Exception {
    // See http://lists.apple.com/archives/java-dev/2010/Oct/msg00026.html .
    final boolean isMacOS = System.getProperty("os.name").contains("Mac OS X");
    final String nat = isMacOS
        // Tested with Excel for Mac 2011.
        ? "CorePasteboardFlavorType 0x454D4253"
        // Tested with Excel for Windows 2013.
        : "Biff8";
    DataFlavor result = new DataFlavor("application/vnd.ms-excel", "Excel BIFF8");
    SystemFlavorMap map = (SystemFlavorMap) SystemFlavorMap.getDefaultFlavorMap();
    map.addUnencodedNativeForFlavor(result, nat);
    map.addFlavorForUnencodedNative(nat, result);
    if (isMacOS && ENABLE_WORKAROUND) {
      // Workaround for the exhibited bug.
      /* Force calling of DataTransferer.getFormatForNativeAsLong, which is necessary for getting
      indexForFormat to return a valid index when CClipboard.getClipboardFormats in
      macosx/native/sun/awt/CClipboard.m calls it. */
      sun.awt.datatransfer.DataTransferer.getInstance().getFormatsForFlavor(result, map);
    }
    return result;
  }
}