treedemo.java

这是一个英文版的《Java程序设计与问题解决》现在好多大学都当成教材

import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.event.TreeSelectionListener;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.tree.TreeSelectionModel;
import java.net.URL;
import java.io.IOException;
import javax.swing.JEditorPane;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JFrame;
import java.awt.*;
import java.awt.event.*;

public class TreeDemo extends JFrame {
    private JEditorPane htmlPane;
    private static boolean DEBUG = false;
    private URL helpURL;

    //Optionally play with line styles.  Possible values are
    //"Angled", "Horizontal", and "None" (the default).
    private boolean playWithLineStyle = false;
    private String lineStyle = "Angled"; 

    public TreeDemo() {
        super("TreeDemo");

        //Create the nodes.
        DefaultMutableTreeNode top = new DefaultMutableTreeNode("The Java Series");
        createNodes(top);

        //Create a tree that allows one selection at a time.
        final JTree tree = new JTree(top);
        tree.getSelectionModel().setSelectionMode
                (TreeSelectionModel.SINGLE_TREE_SELECTION);

        //Listen for when the selection changes.
        tree.addTreeSelectionListener(new TreeSelectionListener() {
            public void valueChanged(TreeSelectionEvent e) {
                DefaultMutableTreeNode node = (DefaultMutableTreeNode)
                                   tree.getLastSelectedPathComponent();

                if (node == null) return;

                Object nodeInfo = node.getUserObject();
                if (node.isLeaf()) {
                    BookInfo book = (BookInfo)nodeInfo;
                    displayURL(book.bookURL);
                    if (DEBUG) {
                        System.out.print(book.bookURL + ":  \n    ");
                    }
                } else {
                    displayURL(helpURL); 
                }
                if (DEBUG) {
                    System.out.println(nodeInfo.toString());
                }
            }
        });

        if (playWithLineStyle) {
            tree.putClientProperty("JTree.lineStyle", lineStyle);
        }

        //Create the scroll pane and add the tree to it. 
        JScrollPane treeView = new JScrollPane(tree);

        //Create the HTML viewing pane.
        htmlPane = new JEditorPane();
        htmlPane.setEditable(false);
        initHelp();
        JScrollPane htmlView = new JScrollPane(htmlPane);

        //Add the scroll panes to a split pane.
        JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
        splitPane.setTopComponent(treeView);
        splitPane.setBottomComponent(htmlView);

        Dimension minimumSize = new Dimension(100, 50);
        htmlView.setMinimumSize(minimumSize);
        treeView.setMinimumSize(minimumSize);
        splitPane.setDividerLocation(100); //XXX: ignored in some releases
                                           //of Swing. bug 4101306
        //workaround for bug 4101306:
        //treeView.setPreferredSize(new Dimension(100, 100)); 

        splitPane.setPreferredSize(new Dimension(500, 300));

        //Add the split pane to this frame.
        getContentPane().add(splitPane, BorderLayout.CENTER);
    }

    private class BookInfo {
        public String bookName;
        public URL bookURL;
        public String prefix = "file:" 
                               + System.getProperty("user.dir")
                               + System.getProperty("file.separator");
        public BookInfo(String book, String filename) {
            bookName = book;
            try {
                bookURL = new URL(prefix + filename);
            } catch (java.net.MalformedURLException exc) {
                System.err.println("Attempted to create a BookInfo "
                                   + "with a bad URL: " + bookURL);
                bookURL = null;
            }
        }

        public String toString() {
            return bookName;
        }
    }

    private void initHelp() {
        String s = null;
        try {
            s = "file:" 
                + System.getProperty("user.dir")
                + System.getProperty("file.separator")
                + "TreeDemoHelp.html";
            if (DEBUG) {
                System.out.println("Help URL is " + s);
            }
            helpURL = new URL(s);
            displayURL(helpURL);
        } catch (Exception e) {
            System.err.println("Couldn't create help URL: " + s);
        }
    }

    private void displayURL(URL url) {
        try {
            htmlPane.setPage(url);
        } catch (IOException e) {
            System.err.println("Attempted to read a bad URL: " + url);
        }
    }

    private void createNodes(DefaultMutableTreeNode top) {
        DefaultMutableTreeNode category = null;
        DefaultMutableTreeNode book = null;

        category = new DefaultMutableTreeNode("Books for Java Programmers");
        top.add(category);

        //original Tutorial
        book = new DefaultMutableTreeNode(new BookInfo
            ("The Java Tutorial: Object-Oriented Programming for the Internet",
            "tutorial.html"));
        category.add(book);

        //Tutorial Continued
        book = new DefaultMutableTreeNode(new BookInfo
            ("The Java Tutorial Continued: The Rest of the JDK",
            "tutorialcont.html"));
        category.add(book);

        //JFC Swing Tutorial
        book = new DefaultMutableTreeNode(new BookInfo
            ("The JFC Swing Tutorial: A Guide to Constructing GUIs",
            "swingtutorial.html"));
        category.add(book);

        //Arnold/Gosling
        book = new DefaultMutableTreeNode(new BookInfo
            ("The Java Programming Language", "arnold.html"));
        category.add(book);

        //FAQ
        book = new DefaultMutableTreeNode(new BookInfo(
            "The Java FAQ", "faq.html"));
        category.add(book);

        //Chan/Lee
        book = new DefaultMutableTreeNode(new BookInfo
            ("The Java Class Libraries: An Annotated Reference",
             "chanlee.html"));
        category.add(book);

        //Threads
        book = new DefaultMutableTreeNode(new BookInfo
            ("Concurrent Programming in Java: Design Principles and Patterns",
             "thread.html"));
        category.add(book);

        category = new DefaultMutableTreeNode("Books for Java Implementers");
        top.add(category);

        //VM
        book = new DefaultMutableTreeNode(new BookInfo
            ("The Java Virtual Machine Specification",
             "vm.html"));
        category.add(book);

        //Language Spec
        book = new DefaultMutableTreeNode(new BookInfo
            ("The Java Language Specification",
             "jls.html"));
        category.add(book);
    }

    public static void main(String[] args) {
        JFrame frame = new TreeDemo();
 
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });  
 
        frame.pack();
        frame.setVisible(true);
    }
}