import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.BoxLayout;
import javax.swing.tree.TreePath;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.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)
*/
public class JTreeDemo
{
public static void main (String[] args)
{
// 构造函数：JTree()
JTree example1 = new JTree();
// 构造函数：JTree(Object[] value)
Object[] letters = { " a " , " b " , " c " , " d " , " e " };
JTree example2 = new JTree (letters);
// 构造函数：JTree(TreeNode root)(TreeNode空)
// 用空结点创建树
DefaultMutableTreeNode node1 = new DefaultMutableTreeNode(); // 定义树结点
JTree example3 = new JTree (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 = new DefaultMutableTreeNode( " Color " );
JTree example4 = new JTree (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 = new DefaultMutableTreeNode( " Color " , true );
DefaultMutableTreeNode gray = new DefaultMutableTreeNode ( " Gray " );
color.add (gray);
color.add ( new DefaultMutableTreeNode ( " Red " ));
gray.add ( new DefaultMutableTreeNode ( " Lightgray " ));
gray.add ( new DefaultMutableTreeNode ( " Darkgray " ));
color.add ( new DefaultMutableTreeNode ( " Green " ));
JTree example5 = new JTree (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 = new DefaultMutableTreeNode ( " Biology " );
DefaultMutableTreeNode animal = new DefaultMutableTreeNode ( " Animal " );
DefaultMutableTreeNode mammal = new DefaultMutableTreeNode ( " Mammal " );
DefaultMutableTreeNode horse = new DefaultMutableTreeNode ( " Horse " ); mammal.add (horse); animal.add (mammal); biology.add (animal); JTree example6 = new JTree (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 = new DefaultMutableTreeNode ( " Root1 " ); DefaultMutableTreeNode child1 = new DefaultMutableTreeNode ( " Child1 " ); DefaultMutableTreeNode child11 = new DefaultMutableTreeNode ( " Child11 " ); DefaultMutableTreeNode child111 = new DefaultMutableTreeNode ( " Child111 " ); root.add (child1); child1.add (child11); child11.add (child111); DefaultTreeModel model = new DefaultTreeModel (root); JTree example7 = new JTree (model); JPanel panel = new JPanel(); panel.setLayout ( new BoxLayout (panel, BoxLayout.X_AXIS)); panel.setPreferredSize ( new Dimension ( 700 , 400 )); panel.add ( new JScrollPane (example1)); // JTree必须放在JScrollPane上 panel.add ( new JScrollPane (example2)); panel.add ( new JScrollPane (example3)); panel.add ( new JScrollPane (example4)); panel.add ( new JScrollPane (example5)); panel.add ( new JScrollPane (example6)); panel.add ( new JScrollPane (example7)); JFrame frame = new JFrame ( " JTreeDemo " ); frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE); frame.setContentPane (panel); frame.pack(); frame.show(); }}
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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);
}
}
}