学步园

树这东西给用户的感觉极为方便，但给程序员带来很大的麻烦，它是swing中最麻烦的控件之一。树要弄的好非常麻烦，图标的美化，层次的划分，各种事件的处理。。。对于初学者来说，就不要太讲究样式，下面举个粗糙的例子，eg

public class SimpleJTree<br /> {<br /> JFrame jf = new JFrame("简单树");</p> <p> JTree tree;<br /> //定义几个初始节点<br /> DefaultMutableTreeNode root = new DefaultMutableTreeNode("中国");<br /> DefaultMutableTreeNode guangdong = new DefaultMutableTreeNode("广东");<br /> DefaultMutableTreeNode guangxi = new DefaultMutableTreeNode("广西");<br /> DefaultMutableTreeNode foshan = new DefaultMutableTreeNode("佛山");<br /> DefaultMutableTreeNode shantou = new DefaultMutableTreeNode("汕头");<br /> DefaultMutableTreeNode guilin = new DefaultMutableTreeNode("桂林");<br /> DefaultMutableTreeNode nanning = new DefaultMutableTreeNode("南宁");</p> <p> public void init()<br /> {<br /> //通过add方法建立树节点之间的父子关系<br /> guangdong.add(foshan);<br /> guangdong.add(shantou);<br /> guangxi.add(guilin);<br /> guangxi.add(nanning);<br /> root.add(guangdong);<br /> root.add(guangxi);<br /> //以根节点创建树<br /> tree = new JTree(root);</p> <p> //默认连线<br /> //tree.putClientProperty("JTree.lineStyle" , "Angeled");<br /> //没有连线<br /> tree.putClientProperty("JTree.lineStyle" , "None");<br /> //水平分隔线<br /> //tree.putClientProperty("JTree.lineStyle" , "Horizontal"); </p> <p> //设置是否显示根节点的“展开/折叠”图标,默认是false<br /> tree.setShowsRootHandles(true);<br /> //设置节点是否可见,默认是true<br /> tree.setRootVisible(true);</p> <p> jf.add(new JScrollPane(tree));<br /> jf.pack();<br /> jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);<br /> jf.setVisible(true);<br /> }</p> <p> public static void main(String[] args)<br /> {<br /> new SimpleJTree().init();<br /> }<br /> }<br />

拖动，编辑树节点也是树的基本功能，下面就在上面例子的基础上，加上这些功能，eg

public class EditJTree<br /> {<br /> JFrame jf;</p> <p> JTree tree;<br /> //上面JTree对象对应的model<br /> DefaultTreeModel model;</p> <p> //定义几个初始节点<br /> DefaultMutableTreeNode root = new DefaultMutableTreeNode("中国");<br /> DefaultMutableTreeNode guangdong = new DefaultMutableTreeNode("广东");<br /> DefaultMutableTreeNode guangxi = new DefaultMutableTreeNode("广西");<br /> DefaultMutableTreeNode foshan = new DefaultMutableTreeNode("佛山");<br /> DefaultMutableTreeNode shantou = new DefaultMutableTreeNode("汕头");<br /> DefaultMutableTreeNode guilin = new DefaultMutableTreeNode("桂林");<br /> DefaultMutableTreeNode nanning = new DefaultMutableTreeNode("南宁");</p> <p> //定义需要被拖动的TreePath<br /> TreePath movePath;</p> <p> JButton addSiblingButton = new JButton("添加兄弟节点");<br /> JButton addChildButton = new JButton("添加子节点");<br /> JButton deleteButton = new JButton("删除节点");<br /> JButton editButton = new JButton("编辑当前节点");</p> <p> public void init()<br /> {<br /> guangdong.add(foshan);<br /> guangdong.add(shantou);<br /> guangxi.add(guilin);<br /> guangxi.add(nanning);<br /> root.add(guangdong);<br /> root.add(guangxi);</p> <p> jf = new JFrame("树");<br /> tree = new JTree(root);<br /> //获取JTree对应的TreeModel对象<br /> model = (DefaultTreeModel)tree.getModel();<br /> //设置JTree可编辑<br /> tree.setEditable(true);<br /> MouseListener ml = new MouseAdapter()<br /> {<br /> //按下鼠标时候获得被拖动的节点<br /> public void mousePressed(MouseEvent e)<br /> {<br /> //如果需要唯一确定某个节点，必须通过TreePath来获取。<br /> TreePath tp = tree.getPathForLocation(e.getX(), e.getY());<br /> if (tp != null)<br /> {<br /> movePath = tp;<br /> }<br /> }<br /> //鼠标松开时获得需要拖到哪个父节点<br /> public void mouseReleased(MouseEvent e)<br /> {<br /> //根据鼠标松开时的TreePath来获取TreePath<br /> TreePath tp = tree.getPathForLocation(e.getX(), e.getY());</p> <p> if (tp != null && movePath != null)<br /> {<br /> //阻止向子节点拖动<br /> if (movePath.isDescendant(tp) && movePath != tp)<br /> {<br /> JOptionPane.showMessageDialog(jf, "目标节点是被移动节点的子节点，无法移动！",<br /> "非法操作", JOptionPane.ERROR_MESSAGE );<br /> return;<br /> }<br /> //既不是向子节点移动，而且鼠标按下、松开的不是同一个节点<br /> else if (movePath != tp)<br /> {<br /> System.out.println(tp.getLastPathComponent());<br /> //add方法可以先将原节点从原父节点删除，再添加到新父节点中<br /> ((DefaultMutableTreeNode)tp.getLastPathComponent()).add(<br /> (DefaultMutableTreeNode)movePath.getLastPathComponent());<br /> movePath = null;<br /> tree.updateUI();<br /> }<br /> }<br /> }<br /> };<br /> tree.addMouseListener(ml);</p> <p> JPanel panel = new JPanel();</p> <p> addSiblingButton.addActionListener(new ActionListener()<br /> {<br /> public void actionPerformed(ActionEvent event)<br /> {<br /> //获取选中节点<br /> DefaultMutableTreeNode selectedNode<br /> = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();<br /> //如果节点为空，直接返回<br /> if (selectedNode == null) return;<br /> //获取该选中节点的父节点<br /> DefaultMutableTreeNode parent<br /> = (DefaultMutableTreeNode)selectedNode.getParent();<br /> //如果父节点为空，直接返回<br /> if (parent == null) return;<br /> //创建一个新节点<br /> DefaultMutableTreeNode newNode = new DefaultMutableTreeNode("新节点");<br /> //获取选中节点的选中索引<br /> int selectedIndex = parent.getIndex(selectedNode);<br /> //在选中位置插入新节点<br /> model.insertNodeInto(newNode, parent, selectedIndex + 1);<br /> //--------下面代码实现显示新节点（自动展开父节点）-------<br /> //获取从根节点到新节点的所有节点<br /> TreeNode[] nodes = model.getPathToRoot(newNode);<br /> //使用指定的节点数组来创建TreePath<br /> TreePath path = new TreePath(nodes);<br /> //显示指定TreePath<br /> tree.scrollPathToVisible(path);<br /> }<br /> });<br /> panel.add(addSiblingButton);</p> <p> addChildButton.addActionListener(new ActionListener()<br /> {<br /> public void actionPerformed(ActionEvent event)<br /> {<br /> //获取选中节点<br /> DefaultMutableTreeNode selectedNode<br /> = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();<br /> //如果节点为空，直接返回<br /> if (selectedNode == null) return;<br /> //创建一个新节点<br /> DefaultMutableTreeNode newNode = new DefaultMutableTreeNode("新节点");<br /> //直接通过model来添加新节点，则无需通过调用JTree的updateUI方法<br /> //model.insertNodeInto(newNode, selectedNode, selectedNode.getChildCount());<br /> //直接通过节点添加新节点，则需要调用tree的updateUI方法<br /> selectedNode.add(newNode);<br /> //--------下面代码实现显示新节点（自动展开父节点）-------<br /> TreeNode[] nodes = model.getPathToRoot(newNode);<br /> TreePath path = new TreePath(nodes);<br /> tree.scrollPathToVisible(path);<br /> tree.updateUI();<br /> }<br /> });<br /> panel.add(addChildButton);</p> <p> deleteButton.addActionListener(new ActionListener()<br /> {<br /> public void actionPerformed(ActionEvent event)<br /> {<br /> DefaultMutableTreeNode selectedNode<br /> = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();<br /> if (selectedNode != null && selectedNode.getParent() != null)<br /> {<br /> //删除指定节点<br /> model.removeNodeFromParent(selectedNode);<br /> }<br /> }<br /> });<br /> panel.add(deleteButton);</p> <p> editButton.addActionListener(new ActionListener()<br /> {<br /> public void actionPerformed(ActionEvent event)<br /> {<br /> TreePath selectedPath = tree.getSelectionPath();<br /> if (selectedPath != null)<br /> {<br /> //编辑选中节点<br /> tree.startEditingAtPath(selectedPath);<br /> }<br /> }<br /> });<br /> panel.add(editButton);</p> <p> jf.add(new JScrollPane(tree));<br /> jf.add(panel , BorderLayout.SOUTH);<br /> jf.pack();<br /> jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);<br /> jf.setVisible(true);<br /> }</p> <p> public static void main(String[] args)<br /> {<br /> new EditJTree().init();<br /> }<br /> }<br />

最后讲下如何修饰tree的图标，主要是通过拓展TreeCellRenderer来实现，eg

public class ExtendsDefaultTreeCellRenderer<br /> {<br /> JFrame jf = new JFrame("根据节点类型定义图标");</p> <p> JTree tree;<br /> //定义几个初始节点<br /> DefaultMutableTreeNode root = new DefaultMutableTreeNode(<br /> new NodeData(DBObjectType.ROOT , "数据库导航"));<br /> DefaultMutableTreeNode salaryDb = new DefaultMutableTreeNode(<br /> new NodeData(DBObjectType.DATABASE , "公司工资数据库"));<br /> DefaultMutableTreeNode customerDb = new DefaultMutableTreeNode(<br /> new NodeData(DBObjectType.DATABASE , "公司客户数据库"));<br /> //定义salaryDb的两个子节点<br /> DefaultMutableTreeNode employee = new DefaultMutableTreeNode(<br /> new NodeData(DBObjectType.TABLE , "员工表"));<br /> DefaultMutableTreeNode attend = new DefaultMutableTreeNode(<br /> new NodeData(DBObjectType.TABLE , "考勤表"));<br /> //定义customerDb的一个子节点<br /> DefaultMutableTreeNode contact = new DefaultMutableTreeNode(<br /> new NodeData(DBObjectType.TABLE , "联系方式表"));</p> <p> //定义employee的三个子节点<br /> DefaultMutableTreeNode id = new DefaultMutableTreeNode(<br /> new NodeData(DBObjectType.INDEX , "员工ID"));<br /> DefaultMutableTreeNode name = new DefaultMutableTreeNode(<br /> new NodeData(DBObjectType.COLUMN , "姓名"));<br /> DefaultMutableTreeNode gender = new DefaultMutableTreeNode(<br /> new NodeData(DBObjectType.COLUMN , "性别"));</p> <p> public void init()throws Exception<br /> {<br /> //通过add方法建立树节点之间的父子关系<br /> root.add(salaryDb);<br /> root.add(customerDb);<br /> salaryDb.add(employee);<br /> salaryDb.add(attend);<br /> customerDb.add(contact);<br /> employee.add(id);<br /> employee.add(name);<br /> employee.add(gender);<br /> //以根节点创建树<br /> tree = new JTree(root);</p> <p> //设置该JTree使用自定义的节点绘制器<br /> tree.setCellRenderer(new MyRenderer());</p> <p> //设置是否显示根节点的“展开/折叠”图标,默认是false<br /> tree.setShowsRootHandles(true);<br /> //设置节点是否可见,默认是true<br /> tree.setRootVisible(true);</p> <p> //设置使用Windows风格外观<br /> UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");<br /> //更新JTree的UI外观<br /> SwingUtilities.updateComponentTreeUI(tree);</p> <p> jf.add(new JScrollPane(tree));<br /> jf.pack();<br /> jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);<br /> jf.setVisible(true);<br /> }</p> <p> public static void main(String[] args) throws Exception<br /> {<br /> new ExtendsDefaultTreeCellRenderer().init();<br /> }<br /> }<br /> //定义一个NodeData类，用于封装节点数据<br /> class NodeData<br /> {<br /> public int nodeType;<br /> public String nodeData;<br /> public NodeData(int nodeType , String nodeData)<br /> {<br /> this.nodeType = nodeType;<br /> this.nodeData = nodeData;<br /> }<br /> public String toString()<br /> {<br /> return nodeData;<br /> }<br /> }<br /> //定义一个接口，该接口里包含数据库对象类型的常量<br /> interface DBObjectType<br /> {<br /> int ROOT = 0;<br /> int DATABASE = 1;<br /> int TABLE = 2;<br /> int COLUMN = 3;<br /> int INDEX = 4;<br /> }<br /> class MyRenderer extends DefaultTreeCellRenderer<br /> {<br /> //初始化5个图标<br /> ImageIcon rootIcon = new ImageIcon("icon/root.gif");<br /> ImageIcon databaseIcon = new ImageIcon("icon/database.gif");<br /> ImageIcon tableIcon = new ImageIcon("icon/table.gif");<br /> ImageIcon columnIcon = new ImageIcon("icon/column.gif");<br /> ImageIcon indexIcon = new ImageIcon("icon/index.gif");</p> <p> public Component getTreeCellRendererComponent(JTree tree, Object value,<br /> boolean sel, boolean expanded, boolean leaf, int row, boolean hasFocus)<br /> {<br /> //执行父类默认的节点绘制操作<br /> super.getTreeCellRendererComponent(tree, value, sel, expanded, leaf, row, hasFocus);</p> <p> DefaultMutableTreeNode node = (DefaultMutableTreeNode)value;<br /> NodeData data = (NodeData)node.getUserObject();<br /> //根据数据节点里的nodeType数据决定节点图标<br /> ImageIcon icon = null;<br /> switch(data.nodeType)<br /> {<br /> case DBObjectType.ROOT:<br /> icon = rootIcon;<br /> break;<br /> case DBObjectType.DATABASE:<br /> icon = databaseIcon;<br /> break;<br /> case DBObjectType.TABLE:<br /> icon = tableIcon;<br /> break;<br /> case DBObjectType.COLUMN:<br /> icon = columnIcon;<br /> break;<br /> case DBObjectType.INDEX:<br /> icon = indexIcon;<br /> break;<br /> }<br /> //改变图标<br /> this.setIcon(icon);<br /> return this;<br /> }<br /> }

原文链接：http://blog.csdn.net/terryzero/article/details/3828045