java - 如何在 Java 中搜索子文件夹并用新数据重新绘制 jTable？

Question

我的程序遇到一些问题。我想要一个 jTable 来显示添加到其 TableModel 中的各种数据点，但我似乎无法使用新数据更新表格。

此外，我在目录中对 png 图像的搜索似乎未能真正在目录中完全搜索所有 png 图像，并且仅在第一个文件夹的内容处停止。

我已将所有数据点放入适合其数据类型的 ArrayList 中，并将它们转换为对象数组，然后再将它们放入 jTable 的 TableModel 中。这没有用，我无法用自己的知识解决这些问题。

一些代码:

private void btnPatchSelActionPerformed(java.awt.event.ActionEvent evt) {                                            
    fchsFolderChooser.showOpenDialog(null);
    File selFile = fchsFolderChooser.getSelectedFile();
    fldPatchSel.setText(selFile.getPath());
    File pngs[] = selFile.listFiles(IMAGE_FILTER);
    for (File png : pngs) {
        try {BufferedImage img = ImageIO.read(png);
            patchWs.add(img.getWidth()); patchHs.add(img.getHeight());
            patchDims.add(img.getWidth() + "x" + img.getHeight());
            patchImgs.add(img); patchImgPaths.add(png.getPath());
            sels.add(false);
            System.out.println("Found " + png.getPath());
        } catch (IOException e) {
            System.out.println("Bad image: " + png); e.printStackTrace();
        }
    }
    if(!(fldPatchSel.getText().endsWith("...")||fldModSel.getText().endsWith("..."))) {BuildTable();}
}

mod 资源选择的对应部分类似，但没有设置 sels ArrayList。

private void BuildTable(){
        DefaultTableModel model = (DefaultTableModel) tblImgList.getModel();
        Object[] boolSels = sels.toArray();
        Object[] stringPatchPaths = patchImgPaths.toArray();
        Object[] stringPatchImgDims = patchDims.toArray();
        model.addColumn("", boolSels);
        model.addColumn("Patch Image", stringPatchPaths);
        model.addColumn("W x H", stringPatchImgDims);
        tblImgList.repaint();
    }

您将如何解决我的两个问题？该程序不搜索子文件夹，并且无法在表中显示新数据。

Answer 1

首先，删除DefaultTableModel，您的数据模型变得越来越复杂。从 POJO(普通旧 Java 对象)开始，它包装了您想要显示的内容的上下文...

public class ImageProperty {

    private File source;
    private Dimension size;
    private boolean selected;

    public ImageProperty(File source, Dimension size, boolean selected) {
        this.source = source;
        this.size = size;
        this.selected = selected;
    }

    public Dimension getSize() {
        return size;
    }

    public File getSource() {
        return source;
    }

    public boolean isSelected() {
        return selected;
    }

}

它保存单个图像文件的所有信息，并将用于表示表中一行的内容。

其次，创建一个自定义TableModel。这是一种个人的事情，但是使用 DefaultTableModel，您会花费更多的时间来解决它，试图让它做您想要的事情，这可以通过使用您自己的来更好地解决...

public class ImageTableModel extends AbstractTableModel {

    private List<ImageProperty> images;

    public ImageTableModel() {
        images = new ArrayList<ImageProperty>(25);
    }

    @Override
    public int getRowCount() {
        return images.size();
    }

    @Override
    public int getColumnCount() {
        return 4;
    }

    @Override
    public String getColumnName(int column) {
        String name = "";
        switch (column) {
            case 1:
                name = "Path";
                break;
            case 2:
                name = "Name";
                break;
            case 3:
                name = "Size";
                break;
        }
        return name;
    }

    @Override
    public Class<?> getColumnClass(int columnIndex) {
        return columnIndex == 0 ? Boolean.class : String.class;
    }

    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        ImageProperty row = images.get(rowIndex);
        Object value = null;
        switch (columnIndex) {
            case 0:
                value = row.isSelected();
                break;
            case 1:
                value = row.getSource().getParent();
                break;
            case 2:
                value = row.getSource().getName();
                break;
            case 3:
                value = row.getSize().width + "x" + row.getSize().height;
                break;
        }
        return value;
    }

    public void addImage(ImageProperty image) {

        images.add(image);
        fireTableRowsInserted(images.size() - 1, images.size() - 1);

    }

    public void addImages(List<ImageProperty> newImages) {

        int firstRow = images.size();
        int lastRow = firstRow + newImages.size() - 1;

        images.addAll(newImages);
        fireTableRowsInserted(firstRow, lastRow);

    }

    public void clear() {

        int lastRow = images.size() -1;
        images.clear();
        fireTableRowsDeleted(0, lastRow);

    }

}

第三，不要尝试在事件调度线程中进行目录扫描，这将导致您的 UI“暂停”直到扫描完成，并且根据图像的大小和子目录的数量，可能会需要几分钟才能完成。

参见Concurrency in Swing了解更多详情...

有多种方法可以解决这个问题，但 SwingWorker 可能是最简单的，因为它提供了安全地向 EDT 提供更新的功能，因此您可以更新 UI，而不会导致进一步的问题...

public class ScanWorker extends SwingWorker<Object, ImageProperty> {

    private File source;
    private ImageTableModel model;

    public ScanWorker(File source, ImageTableModel model) {
        this.source = source;
        this.model = model;
    }

    @Override
    protected void process(List<ImageProperty> chunks) {
        model.addImages(chunks);
    }

    @Override
    protected Object doInBackground() throws Exception {
        scan(source);
        return null;
    }

    protected void scan(File dir) {
        firePropertyChange("directory", dir.getParent(), dir);
        File pngs[] = dir.listFiles(new FileFilter() {
            @Override
            public boolean accept(File pathname) {
                return pathname.getName().toLowerCase().endsWith(".png");
            }
        });
        for (File png : pngs) {
            try {
                BufferedImage img = ImageIO.read(png);
                publish(new ImageProperty(png, new Dimension(img.getWidth(), img.getHeight()), false));
            } catch (IOException e) {
                System.out.println("Bad image: " + png);
                e.printStackTrace();
            }
        }
        File dirs[] = dir.listFiles(new FileFilter() {
            @Override
            public boolean accept(File pathname) {
                return pathname.isDirectory();
            }
        });
        if (dirs != null && dirs.length > 0) {
            for (File subDir : dirs) {
                scan(subDir);
            }
        }
    }

}

该工作人员使用递归方法调用来扫描子目录...

最后是胶水......

此代码片段禁用“扫描”按钮，清除当前表模型，创建 SwingWorker 并向其注册 PropertyChangeListener，最后启动工作器...

model.clear();
scan.setEnabled(false);
ScanWorker worker = new ScanWorker(new File("..."), model);
worker.addPropertyChangeListener(new PropertyChangeListener() {
    @Override
    public void propertyChange(PropertyChangeEvent evt) {
        if ("state".equalsIgnoreCase(evt.getPropertyName())) {
            SwingWorker.StateValue state = (SwingWorker.StateValue) evt.getNewValue();
            scan.setEnabled(state == SwingWorker.StateValue.DONE);
            scan.setText("Scan");
        } else if ("directory".equalsIgnoreCase(evt.getPropertyName())) {

            scan.setText(text);

        }
    }
});
worker.execute();

PropertyChangeListener 监视工作线程状态的更改，并在完成时将按钮重置为启用状态。它还监视扫描目录的更改并更新按钮的文本以反射(reflect)当前已处理的目录...很好

上面的代码片段是由附加到“扫描”按钮的ActionListener触发的

还有一个很好的可运行示例...

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingWorker;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.table.AbstractTableModel;

public class ShowImages {

    public static void main(String[] args) {
        new ShowImages();
    }

    public ShowImages() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                final ImageTableModel model = new ImageTableModel();
                JTable table = new JTable(model);

                final JButton scan = new JButton("Scan");
                scan.addActionListener(new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        model.clear();
                        scan.setEnabled(false);
                        ScanWorker worker = new ScanWorker(new File("C:\\Users\\shane\\Dropbox\\MegaTokyo"), model);
                        worker.addPropertyChangeListener(new PropertyChangeListener() {
                            @Override
                            public void propertyChange(PropertyChangeEvent evt) {
                                if ("state".equalsIgnoreCase(evt.getPropertyName())) {
                                    SwingWorker.StateValue state = (SwingWorker.StateValue) evt.getNewValue();
                                    scan.setEnabled(state == SwingWorker.StateValue.DONE);
                                    scan.setText("Scan");
                                } else if ("directory".equalsIgnoreCase(evt.getPropertyName())) {

                                    String text = ((File)evt.getNewValue()).getPath().replaceAll("shane", "...");
                                    text = text.replaceAll("C:\\\\", "...");
                                    text = text.replaceAll("Dropbox", "...");
                                    scan.setText(text);

                                }
                            }
                        });
                        worker.execute();
                    }
                });

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new JScrollPane(table));
                frame.add(scan, BorderLayout.SOUTH);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class ImageProperty {

        private File source;
        private Dimension size;
        private boolean selected;

        public ImageProperty(File source, Dimension size, boolean selected) {
            this.source = source;
            this.size = size;
            this.selected = selected;
        }

        public Dimension getSize() {
            return size;
        }

        public File getSource() {
            return source;
        }

        public boolean isSelected() {
            return selected;
        }

    }

    public class ImageTableModel extends AbstractTableModel {

        private List<ImageProperty> images;

        public ImageTableModel() {
            images = new ArrayList<ImageProperty>(25);
        }

        @Override
        public int getRowCount() {
            return images.size();
        }

        @Override
        public int getColumnCount() {
            return 4;
        }

        @Override
        public String getColumnName(int column) {
            String name = "";
            switch (column) {
                case 1:
                    name = "Path";
                    break;
                case 2:
                    name = "Name";
                    break;
                case 3:
                    name = "Size";
                    break;
            }
            return name;
        }

        @Override
        public Class<?> getColumnClass(int columnIndex) {
            return columnIndex == 0 ? Boolean.class : String.class;
        }

        @Override
        public Object getValueAt(int rowIndex, int columnIndex) {
            ImageProperty row = images.get(rowIndex);
            Object value = null;
            switch (columnIndex) {
                case 0:
                    value = row.isSelected();
                    break;
                case 1:
                    value = row.getSource().getParent();
                    break;
                case 2:
                    value = row.getSource().getName();
                    break;
                case 3:
                    value = row.getSize().width + "x" + row.getSize().height;
                    break;
            }
            return value;
        }

        public void addImage(ImageProperty image) {

            images.add(image);
            fireTableRowsInserted(images.size() - 1, images.size() - 1);

        }

        public void addImages(List<ImageProperty> newImages) {

            int firstRow = images.size();
            int lastRow = firstRow + newImages.size() - 1;

            images.addAll(newImages);
            fireTableRowsInserted(firstRow, lastRow);

        }

        public void clear() {

            int lastRow = images.size() -1;
            images.clear();
            fireTableRowsDeleted(0, lastRow);

        }

    }

    public class ScanWorker extends SwingWorker<Object, ImageProperty> {

        private File source;
        private ImageTableModel model;

        public ScanWorker(File source, ImageTableModel model) {
            this.source = source;
            this.model = model;
        }

        @Override
        protected void process(List<ImageProperty> chunks) {
            model.addImages(chunks);
        }

        @Override
        protected Object doInBackground() throws Exception {
            scan(source);
            return null;
        }

        protected void scan(File dir) {
            firePropertyChange("directory", dir.getParent(), dir);
            File pngs[] = dir.listFiles(new FileFilter() {
                @Override
                public boolean accept(File pathname) {
                    return pathname.getName().toLowerCase().endsWith(".png");
                }
            });
            for (File png : pngs) {
                try {
                    BufferedImage img = ImageIO.read(png);
                    publish(new ImageProperty(png, new Dimension(img.getWidth(), img.getHeight()), false));
                } catch (IOException e) {
                    System.out.println("Bad image: " + png);
                    e.printStackTrace();
                }
            }
            File dirs[] = dir.listFiles(new FileFilter() {
                @Override
                public boolean accept(File pathname) {
                    return pathname.isDirectory();
                }
            });
            if (dirs != null && dirs.length > 0) {
                for (File subDir : dirs) {
                    scan(subDir);
                }
            }
        }

    }

}

看看Worker Threads and SwingWorker了解更多详情