JTree用法及JTree使用經驗總結
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的構造函數: JTree() JTree(Hashtable value) JTree(Object[] value)//只有這個構造函數可以創建多個根結點 JTree(TreeModel newModel) JTree(TreeNode root) JTree(TreeNode root, boolean asksAllowsChildren) JTree(Vector value)*/ public class JTreeDemo { public static void main (String[] args) { // 構造函數：JTree() JTree example1 = new JTree(); // 構造函數：JTree(Object[] value) Object[] letters = { " a " , " b " , " c " , " d " , " e " }; JTree example2 = new JTree (letters); // 構造函數：JTree(TreeNode root)(TreeNode空) // 用空結點創建樹 DefaultMutableTreeNode node1 = new DefaultMutableTreeNode(); // 定義樹結點 JTree example3 = new JTree (node1); // 用此樹結點做參數調用 JTree的構造函數創建含有一個根結點的樹 // 構造函數：JTree(TreeNode root)(同上,只是TreeNode非空) // 用一個根結點創建樹 DefaultMutableTreeNode node2 = new DefaultMutableTreeNode( " Color " ); JTree example4 = new JTree (node2); // 結點不可以顏色,默認為白面黑字 example4.setBackground (Color.lightGray); // 構造函數：JTree(TreeNode root, boolean asksAllowsChildren)(同上,只是TreeNode又有不同) // 使用DefaultMutableTreeNode類先用一個根結點創建樹，設置為可添加孩子結點,再添加孩子結點 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); // 構造函數：JTree(TreeNode root)(同上,只是TreeNode非空) // 通過逐個添加結點創建樹 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(); // 構造函數:JTree(TreeModel newModel) // 用DefaultMutableTreeNodel類定義一個結點再用這個結點做參數定義一個用DefaultTreeMode // 創建一個樹的模型,再用JTree的構造函數創建一個樹 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必須放在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(); } } </pre><br />在實際開發過程中會經常使用JTree組件，平時會遇到這樣或那樣的問題，在此將偶得一點經驗寫下來，與大家共享，希望對大家有所幫助。
private JTree jtNetDevice;//數組件申明
private JScrollPane jspTree;//滾動面板申明
1、初始化
DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("root");
jtNetDevice = new JTree(rootNode);
jtNetDevice.setAutoscrolls(true);
getTreeSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);//設置單選模式
jspTree = new JScrollPane();
jspTree.getViewport().add(jtNetDevice, null);2、三個經常使用的取值函數
private DefaultTreeModel getTreeModel(){
return (DefaultTreeModel)jtNetDevice.getModel();
}private DefaultMutableTreeNode getRootNode(){
return (DefaultMutableTreeNode)getTreeModel().getRoot();
}
private TreeSelectionModel getTreeSelectionModel(){
return jtNetDevice.getSelectionModel();
}3、根據node得到path：
TreePath visiblePath = new TreePath(getTreeModel().getPathToRoot(node));4、根據Path展開到該節點
jtNetDevice.makeVisible(visiblePath);5、根據path設定該節點選定
jtNetDevice.setSelectionPath(visiblePath);6、選中節點的方法
首先，根據節點得到樹路徑，其中chosen為需要選中的節點
TreePath visiblePath = new TreePath( ( (DefaultTreeModel) jtNetDevice.getModel()).
getPathToRoot(chosen));
然后根據Path選中該節點
jtNetDevice.setSelectionPath(visiblePath);7、滾動到可見位置
jtNetDevice.scrollPathToVisible(visiblePath);8、給JTree添加右鍵彈出菜單
void jtNetDevice_mouseReleased(MouseEvent e) {
if (e.isPopupTrigger()) {
jPopupMenu1.show(e.getComponent(), e.getX(), e.getY());//彈出右鍵菜單
}
}9、關于JTree的展開
// 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、如何遍歷JTree
// 創建樹
JTree tree = new JTree();
// 添加樹節點......
// 遍歷所有節點
visitAllNodes(tree);
// 僅遍歷展開的節點
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);
}
}
}