importjava.awt.Dimension;
importjava.awt.Color;
importjavax.swing.JFrame;
importjavax.swing.JPanel;
importjavax.swing.JScrollPane;
importjavax.swing.JTree;
importjavax.swing.BoxLayout;
importjavax.swing.tree.TreePath;
importjavax.swing.tree.DefaultMutableTreeNode;
importjavax.swing.tree.DefaultTreeModel;
/*
JTree的构造函数:
JTree()
JTree(Hashtable value)
JTree(Object[] value)//只有这个构造函数可以创建多个根结点
JTree(TreeModel newModel)
JTree(TreeNode root)
JTree(TreeNode root, boolean asksAllowsChildren)
JTree(VecTor value)
*/
publicclassJTreeDemo
{
publicstaticvoidmain (String[] args)
{
// 构造函数：JTree()
JTree example1=newJTree();
// 构造函数：JTree(Object[] value)
Object[] letters ={ ” a ” ,” b ” ,” c ” ,” d ” ,” e ” };
JTree example2=newJTree (letters);
// 构造函数：JTree(TreeNode root)(TreeNode空)
// 用空结点创建树
DefaultMutableTreeNode node1=newDefaultMutableTreeNode(); // 定义树结点
JTree example3=newJTree (node1); // 用此树结点做参数调用JTree的构造函数创建含有一个根结点的树
// 构造函数：JTree(TreeNode root)(同上,只是TreeNode非空)
// 用一个根结点创建树
DefaultMutableTreeNode node2=newDefaultMutableTreeNode( ” Color ” );
JTree example4=newJTree (node2); // 结点不可以颜色,默认为白面黑字
example4.setBackground (Color.lightGray);
// 构造函数：JTree(TreeNode root, boolean asksAllowsChildren)(同上,只是TreeNode又有不同)
// 使用DefaultMutableTreeNode类先用一个根结点创建树，设置为可添加孩子结点,再添加孩子结点
DefaultMutableTreeNode color=newDefaultMutableTreeNode( ” Color ” ,true );
DefaultMutableTreeNode gray=newDefaultMutableTreeNode ( ” Gray ” );
color.add (gray);
color.add ( newDefaultMutableTreeNode ( ” Red ” ));
gray.add ( newDefaultMutableTreeNode ( ” Lightgray ” ));
gray.add ( newDefaultMutableTreeNode ( ” Darkgray ” ));
color.add ( newDefaultMutableTreeNode ( ” Green ” ));
JTree example5=newJTree (color);
// 构造函数：JTree(TreeNode root)(同上,只是TreeNode非空)
// 通过逐个添加结点创建树
DefaultMutableTreeNode biology=newDefaultMutableTreeNode ( ” Biology ” );
DefaultMutableTreeNode animal=newDefaultMutableTreeNode ( ” Animal ” );
DefaultMutableTreeNode mammal=newDefaultMutableTreeNode ( ” Mammal ” );
DefaultMutableTreeNode horse=newDefaultMutableTreeNode ( ” Horse ” );
mammal.add (horse);
animal.add (mammal);
biology.add (animal);
JTree example6=newJTree (biology);
horse.isLeaf();
horse.isRoot();
// 构造函数:JTree(TreeModel newModel)
// 用DefaultMutableTreeNodel类定义一个结点再用这个结点做参数定义一个用DefaultTreeMode
// 创建一个树的模型,再用JTree的构造函数创建一个树
DefaultMutableTreeNode root=newDefaultMutableTreeNode ( ” Root1 ” );
DefaultMutableTreeNode child1=newDefaultMutableTreeNode ( ” Child1 ” );
DefaultMutableTreeNode child11=newDefaultMutableTreeNode ( ” Child11 ” );
DefaultMutableTreeNode child111=newDefaultMutableTreeNode ( ” Child111 ” );
root.add (child1); child1.add (child11); child11.add (child111);
DefaultTreeModel model=newDefaultTreeModel (root);
JTree example7=newJTree (model);
JPanel panel=newJPanel();
panel.setLayout ( newBoxLayout (panel, BoxLayout.X_AXIS));
panel.setPreferredSize ( newDimension ( 700 ,400 ));
panel.add ( newJScrollPane (example1)); // JTree必须放在JScrollPane上
panel.add ( newJScrollPane (example2));
panel.add ( newJScrollPane (example3));
panel.add ( newJScrollPane (example4));
panel.add ( newJScrollPane (example5));
panel.add ( newJScrollPane (example6));
panel.add ( newJScrollPane (example7));
JFrame. frame=newJFrame. ( ” JTreeDemo ” );
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
frame.setContentPane (panel);
frame.pack();
frame.show();
}
} ××××××××××××××××××××××××××××××××××××××××××××××
在实际开发过程中会经常使用JTree组件，平时会遇到这样或那样的问题，在此将偶得一点经验写下来，与大家共享，希望对大家有所帮助。
private JTree jtNetDevice;//数组件申明
private JScrollPane jspTree;//滚动面板申明
1、初始化
DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode(“root”);
jtNetDevice = new JTree(rootNode);
jtNetDevice.setAutoscrolls(true);
getTreeSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);//设置单选模式
jspTree = new JScrollPane();
jspTree.getViewport().add(jtNetDevice, null);
2、三个经常使用的取值函数
private DefaultTreeModel getTreeModel(){
return (DefaultTreeModel)jtNetDevice.getModel();
}
private DefaultMutableTreeNode getRootNode(){
return (DefaultMutableTreeNode)getTreeModel().getRoot();
}
private TreeSelectionModel getTreeSelectionModel(){
return jtNetDevice.getSelectionModel();
}
3、根据node得到path：
TreePath visiblePath = new TreePath(getTreeModel().getPathToroot(node));
4、根据Path展开到该节点
jtNetDevice.makeVisible(visiblePath);
5、根据path设定该节点选定
jtNetDevice.setSelectionPath(visiblePath);
6、选中节点的方法
首先，根据节点得到树路径，其中chosen为需要选中的节点
TreePath visiblePath = new TreePath( ( (DefaultTreeModel) jtNetDevice.getModel()).
getPathToroot(chosen));
然后根据Path选中该节点
jtNetDevice.setSelectionPath(visiblePath);
7、滚动到可见位置
jtNetDevice.scrollPathToVisible(visiblePath);
8、给JTree添加右键弹出菜单
void jtNetDevice_mouseReleased(MouseEvent e) {
if (e.isPopupTrigger()) {
jPopupMenu1.show(e.getComponent(), e.getX(), e.getY());//弹出右键菜单
}
}
9、关于JTree的展开
// If expand is true, expands all nodes in the tree.
// Otherwise, collapses all nodes in the tree.
public void expandAll(JTree tree, boolean expand) {
TreeNode root = (TreeNode)tree.getModel().getRoot();
// Traverse tree from root
expandAll(tree, new TreePath(root), expand);
private void expandAll(JTree tree, TreePath parent, boolean expand) {
// Traverse children
TreeNode node = (TreeNode)parent.getLastPathComponent();
if (node.getChildCount() >= 0) {
for (Enumeration e=node.children(); e.hasMoreElements(); ) {
TreeNode n = (TreeNode)e.nextElement();
TreePath path = parent.pathByAddingChild(n);
expandAll(tree, path, expand);
}
}
// Expansion or collapse must be done bottom-up
if (expand) {
tree.expandPath(parent);
} else {
tree.collapsePath(parent);
}
}
10、如何遍历JTree
// 创建树
JTree tree = new JTree();
// 添加树节点……
// 遍历所有节点
visitAllNodes(tree);
// 仅遍历展开的节点
visitAllExpandedNodes(tree);
// Traverse all nodes in tree
public void visitAllNodes(JTree tree) {
TreeNode root = (TreeNode)tree.getModel().getRoot();
visitAllNodes(root);
}
public void visitAllNodes(TreeNode node) {
// node is visited exactly once
process(node);
if (node.getChildCount() >= 0) {
for (Enumeration e=node.children(); e.hasMoreElements(); ) {
TreeNode n = (TreeNode)e.nextElement();
visitAllNodes(n);
}
}
}
// Traverse all expanded nodes in tree
public void visitAllExpandedNodes(JTree tree) {
TreeNode root = (TreeNode)tree.getModel().getRoot();
visitAllExpandedNodes(tree, new TreePath(root));
}
public void visitAllExpandedNodes(JTree tree, TreePath parent) {
// Return if node is not expanded
if (!tree.isVisible(parent)) {
return;
}
// node is visible and is visited exactly once
TreeNode node = (TreeNode)parent.getLastPathComponent();
process(node);
// Visit all children
if (node.getChildCount() >= 0) {
for (Enumeration e=node.children(); e.hasMoreElements(); ) {
TreeNode n = (TreeNode)e.nextElement();
TreePath path = parent.pathByAddingChild(n);
visitAllExpandedNodes(tree, path);
}
}
}
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