ClipboardServiceでシステム全体の共有クリップボードにアクセスする

ClipboardService cs;
try {
  cs = (ClipboardService) ServiceManager.lookup("javax.jnlp.ClipboardService");
} catch (Throwable t) {
  cs = null;
}
JTextArea textArea = new JTextArea() {
  @Override public void copy() {
    if (cs != null) {
      cs.setContents(new StringSelection(getSelectedText()));
    }
    super.copy();
  }

  @Override public void cut() {
    if (cs != null) {
      cs.setContents(new StringSelection(getSelectedText()));
    }
    super.cut();
  }

  @Override public void paste() {
    if (cs != null) {
      Transferable tr = cs.getContents();
      if (tr.isDataFlavorSupported(DataFlavor.stringFlavor)) {
        try {
          getTransferHandler().importData(this, tr);
        } catch (Exception e) {
          e.printStackTrace();
        }
      }
    } else {
      super.paste();
    }
  }
};