对jtree实现增加修改，设置节点图片

public void actionPerformed(ActionEvent e) {
		DefaultMutableTreeNode selectNode = (DefaultMutableTreeNode) tree
				.getLastSelectedPathComponent();
		if (selectNode == null) {
			return;
		}
		// 事件命令
		String command = e.getActionCommand();
		if ("delete".equals(command)) { // 如果是删除
			if (selectNode.getParent() != null) {
				model.removeNodeFromParent(selectNode);

			}
		} else if ("insert".equals(command)) { // 如果是插入
			String message = JOptionPane.showInputDialog("请输入您要插入子节点的名称"); // 点击取消返回null
			if (message != null && !"".equals(message.trim())) {
				DefaultMutableTreeNode newNode = new DefaultMutableTreeNode(
						message);
				model.insertNodeInto(newNode, selectNode, selectNode
						.getChildCount());

			}

		} else if ("insertNode".equals(command)) { // 如果是插入
			String message = JOptionPane.showInputDialog("请输入您要插入节点的名称"); // 点击取消返回null
			if (message != null && !"".equals(message.trim())) {
				DefaultMutableTreeNode newNode = new DefaultMutableTreeNode(
						message);

				DefaultMutableTreeNode parentNode = (DefaultMutableTreeNode) selectNode
						.getParent();
				if (parentNode != null) {
					int selectIndex = parentNode.getIndex(selectNode);

					model.insertNodeInto(newNode, parentNode, selectIndex + 1);
				}
			}

		} else if ("update".equals(command)) { // 修改节点名称
			String name = selectNode.getUserObject().toString();
			String message = JOptionPane.showInputDialog(null, "请输入您要插入节点的名称",
					name); // 点击取消返回null
			if (message != null) {
				selectNode.setUserObject(message);
				tree.repaint();
			}
		} else if ("addstu".equals(command)) { // 增加学生
			pnlStudent.setVisible(true);
			cleanStuInput();

		} else if ("updatestu".equals(command)) { // 修改学生信息
			getTableValueToPanel();

		} else if ("delstu".equals(command)) { // 删除学生信息
			DefaultTableModel model = (DefaultTableModel) table.getModel();
			int row = table.getSelectedRow();
			if (row == -1) {
				return;
			}
			String stuId = table.getValueAt(row, 5).toString(); // 学号
			model.removeRow(row);
			table.setModel(model);
			table.repaint();
			// 删除xml中的数据
			(new StudentDao()).deleteStudent(selectNode.toString(), stuId);

		}

	}

// 为树设置图片
		DefaultTreeCellRenderer renderer = (DefaultTreeCellRenderer) tree
				.getCellRenderer();
		renderer.setOpenIcon(new ImageIcon("img/folderopen.gif"));
		renderer.setClosedIcon(new ImageIcon("img/folder.gif"));
		renderer.setLeafIcon(new ImageIcon("img/page.gif"));
		renderer.setIcon(new ImageIcon("img/base.gif"));