import java.awt.Dimension;
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(); }}
××××××××××××××××××××××××××××××××××××××××××××××
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);
}
}
}