使用 JTextField ENTER 启动 JTree

Question

我是新手，JTree 让我很伤心。坚持不下去了所以希望，你能帮助我。 我真正想要的是，正确显示JTextField 和JTree，当我从PC 写入路径时，我想查看JTree 中的所有文件夹和文件。 我做了一些事情，但真的希望你能帮助我。谢谢。

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;

public class Main extends JFrame {
    JTextField path = new JTextField();

    public static void main(String[] args) {
        new Main().setVisible(true);
    }

    private JTree jTree1;
    private JTree jTree2;
    File fileRoot;
    File fileRoot2;
    DefaultMutableTreeNode root = new DefaultMutableTreeNode(fileRoot);
    DefaultTreeModel model = new DefaultTreeModel(root);
    DefaultMutableTreeNode root2 = new DefaultMutableTreeNode(fileRoot2);
    DefaultTreeModel model2 = new DefaultTreeModel(root2);

    public Main() {
        setLayout(new BorderLayout());
        this.jTree1 = new JTree();
        this.add(this.jTree1);
        this.jTree2 = new JTree();
        this.add(this.jTree2);
        JScrollPane scrollpane = new JScrollPane();
        scrollpane.setBounds(100, 100, 100, 300);
        scrollpane.getViewport().add(jTree1);
        add(BorderLayout.NORTH, path);
        add(BorderLayout.WEST, scrollpane);
        JScrollPane scrollpane2 = new JScrollPane();
        scrollpane2.getViewport().add(jTree2);
        add(BorderLayout.EAST, scrollpane2);
        this.jTree1.setModel(model);
        this.jTree2.setModel(model2);
        this.pack();
        path.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String JtreeString = path.getText().toString().replaceAll("[\\[\\]]", "")
                        .replace(", ", "\\");
                fileRoot = new File(JtreeString);
                File[] files = fileRoot.listFiles();
                for (File file : files) {
                    root.add(new DefaultMutableTreeNode(file));
                }
                model.reload(root);
            }
        });
    }
}

Answer 1

我重写了你的代码。
我不清楚为什么你有两个JTrees。以下代码仅填充左侧树。
（说明出现在代码后面。）

import java.awt.BorderLayout;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.io.File;
import java.nio.file.Path;
import java.nio.file.Paths;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;

public class FileTree implements Runnable {
    private DefaultTreeModel  leftModel;
    private JFrame  frame;
    private JTextField  filePathTextField;
    private JTree  leftTree;
    private JTree  rightTree;

    public void run() {
        createAndDisplayGui();
    }

    private void createAndDisplayGui() {
        frame = new JFrame("File Tree");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(createTopPanel(), BorderLayout.PAGE_START);
        frame.add(createTreesPanel(), BorderLayout.CENTER);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    private JPanel createTopPanel() {
        JPanel topPanel = new JPanel();
        topPanel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
        JLabel label = new JLabel("Root Path");
        label.setDisplayedMnemonic(KeyEvent.VK_R);
        label.setLabelFor(filePathTextField);
        topPanel.add(label);
        filePathTextField = new JTextField(20);
        filePathTextField.addActionListener(this::walkFileTree);
        topPanel.add(filePathTextField);
        return topPanel;
    }

    private JPanel createTreesPanel() {
        JPanel treesPanel = new JPanel(new GridLayout(1, 0, 10, 0));
        treesPanel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
        leftTree = new JTree(new DefaultTreeModel(null));
        leftTree.setShowsRootHandles(true);
        JScrollPane leftScrollPane = new JScrollPane(leftTree);
        leftScrollPane.setPreferredSize(new Dimension(300, 300));
        treesPanel.add(leftScrollPane);
        rightTree = new JTree(new DefaultTreeModel(null));
        JScrollPane rightScrollPane = new JScrollPane(rightTree);
        rightScrollPane.setPreferredSize(new Dimension(300, 300));
        treesPanel.add(rightScrollPane);
        return treesPanel;
    }

    private void expandAllNodes(JTree tree, int startingIndex, int rowCount){
        for (int i = startingIndex; i < rowCount; ++i) {
            tree.expandRow(i);
        }
        if (tree.getRowCount() != rowCount) {
            expandAllNodes(tree, rowCount, tree.getRowCount());
        }
    }

    private void walkFileTree(ActionEvent event) {
        Object source = event.getSource();
        if (source == filePathTextField) {
            frame.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
            String text = filePathTextField.getText();
            Path rootPath = Paths.get(text);
            File rootFile = rootPath.toFile();
            DefaultMutableTreeNode root = new DefaultMutableTreeNode(rootFile);
            leftModel = new DefaultTreeModel(root);
            leftTree.setModel(leftModel);
            walkTree(root, rootFile);
            expandAllNodes(leftTree, 0, leftTree.getRowCount());
            frame.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
        }
    }

    private void walkTree(DefaultMutableTreeNode parent, File f) {
        if (f.isDirectory()) {
            File[] files = f.listFiles();
            for (File file : files) {
                DefaultMutableTreeNode node = new DefaultMutableTreeNode(file);
                parent.add(node);
                if (file.isDirectory()) {
                    walkTree(node, file);
                }
            }
        }
    }

    public static void main(String[] args) {
        FileTree gui = new FileTree();
        EventQueue.invokeLater(gui);
    }
}

• JFrame 的 [内容窗格] 的默认 layout manager 是 BorderLayout，因此无需显式设置。
• 为了并排显示JTrees，我使用了GridLayout，但还有其他布局管理器可以达到相同的效果。
• 您在JTextField 中输入路径的文件下的文件越多，显示结果所需的时间就越长。这就是我在构建树时将光标设置为“等待”光标的原因。请注意，这不会阻止用户使用鼠标，但是在构建树时，event dispatch thread (EDT) 无论如何都无法响应鼠标点击。基本上它是向用户提示应用程序正忙。您可能需要考虑使用SwingWorker。
• 方法 expandAllNodes 是从这个 SO 问题的答案中复制的：Completely expand all node of a Jtree (including children)
• this::walkFileTree 是 method reference 的语法。
• How to Use Trees

这是一个屏幕截图：