Answer 1

Nick Meyer感谢您的回复，而您地址中的内容有点过时了。我用jre 1.7运行它并没有按预期工作但它可以改变工作正确。 我所做的改变如下

/*
* add these code in GroupableTableHeader
*/

  public void updateUI(){
//      setUI(this.getUI());

      TableCellRenderer renderer = getDefaultRenderer();
      if (renderer instanceof Component) {
          SwingUtilities.updateComponentTreeUI((Component)renderer);
      }
  }

/*
* add these code in GroupableTableHeaderUI in 2 places, you must know where
*/
      if (renderer == null) {
          renderer = header.getDefaultRenderer();
      }

/*
* change the getSize method in ColumnGroup 
*/

  public Dimension getSize(JTable table) {
    Component comp = renderer.getTableCellRendererComponent(
        table, getHeaderValue(), false, false,-1, -1);
    int height = comp.getPreferredSize().height; 
    int width  = 0;
    Enumeration en = v.elements();
    while (en.hasMoreElements()) {
      Object obj = en.nextElement();
      if (obj instanceof TableColumn) {
        TableColumn aColumn = (TableColumn)obj;
        width += aColumn.getWidth();
//        width += margin;
      } else {
        width += ((ColumnGroup)obj).getSize(table).width;
      }
    }
    return new Dimension(width, height);
  }

并最终结果。

Answer 2

Answer 3