将文件从操作系统拖放到 JTable java

drag and drop files from OS into JTable java(将文件从操作系统拖放到 JTable java)

问题描述

谁能告诉我我做错了什么?我可以使用常规面板进行拖放操作，但现在尝试使用表格，但无法对其进行整理.我对 Points 和 DropTargets 感到困惑.不要介意添加"按钮.我觉得我需要先处理 DnD.

Can someone show me what I'm doing wrong? I was able to get drag and drop working with a regular panel but now trying with a table and I can't sort it out. I'm getting confused with the Points and DropTargets. Dont mind the "Add" button. I feel like I need to deal with the DnD first.

public class Table extends JFrame implements ActionListener {

    private JTable table;
    private JScrollPane scroll;
    private JButton add;
    private JFileChooser choose;
    private JMenuBar menubar;
    private JMenu menu;
    private JMenuItem file;
    private DefaultTableModel tm = new DefaultTableModel(new String[] { "File",
            "File Type", "Size", "Status" }, 2);

    public Table() {

        // String column [] = {"Filename ","File Type", "Size", "Status" };
        /*
         * Object[][] data = { {"File1", ".jpg","32 MB", "Not Processed"},
         * {"File2", ".txt"," 5 Kb", "Not Processed"}, {"File3", ".doc","3 Kb",
         * "Not Processed"},
         * };
         */

        table = new JTable();
        table.setModel(tm);
        table.setFillsViewportHeight(true);
        table.setPreferredSize(new Dimension(500, 300));

        scroll = new JScrollPane(table);

        table.setDropTarget(new DropTarget() {
            @Override
            public synchronized void drop(DropTargetDropEvent dtde) {

                Point point = dtde.getLocation();
                int column = table.columnAtPoint(point);
                int row = table.rowAtPoint(point);

                dtde.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
                Transferable t = dtde.getTransferable();
                List fileList = null;
                try {
                    fileList = (List) t
                            .getTransferData(DataFlavor.javaFileListFlavor);
                } catch (UnsupportedFlavorException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                File f = (File) fileList.get(0);
                table.setValueAt(f.getAbsolutePath(), row, column);
                table.setValueAt(f.length(), row, column + 1);
                super.drop(dtde);
            }
        });
        scroll.setDropTarget(new DropTarget() {
            @Override
            public synchronized void drop(DropTargetDropEvent dtde) {
                Point point = dtde.getLocation();
                int column = table.columnAtPoint(point);
                int row = table.rowAtPoint(point);

                dtde.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
                Transferable t = dtde.getTransferable();
                List fileList = null;
                try {
                    fileList = (List) t
                            .getTransferData(DataFlavor.javaFileListFlavor);
                } catch (UnsupportedFlavorException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                File f = (File) fileList.get(0);
                table.setValueAt(f.getAbsolutePath(), row, column);
                table.setValueAt(f.length(), row, column + 1);
                // handle drop outside current table (e.g. add row)
                super.drop(dtde);
            }
        });

        add(scroll, BorderLayout.CENTER);

        menubar = new JMenuBar();
        menu = new JMenu("File");
        file = new JMenuItem("file");
        menu.add(file);
        // menubar.add(menu);
        add(menu, BorderLayout.NORTH);

        ImageIcon icon = new ImageIcon("lock_icon.png");

        add = new JButton("Add", icon);
        add.addActionListener(this);

        JFileChooser choose = new JFileChooser();
        choose.addActionListener(this);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        JButton clicked = (JButton) e.getSource();

        int returnValue = 0;

        if (clicked == add) {
            choose = new JFileChooser();
            choose.showOpenDialog(null);

            if (returnValue == JFileChooser.APPROVE_OPTION) {
                File file = choose.getSelectedFile();
                file.getAbsolutePath();

            }

        }

    }

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {

                Table t = new Table();

                t.setDefaultCloseOperation(EXIT_ON_CLOSE);
                t.pack();
                t.setSize(600, 200);
                t.setVisible(true);
                t.setTitle("ZipLock");
                t.setIconImage(null);

            }
        });

    }

}

推荐答案

我个人会放弃滚动窗格上的放置目标，这会给你带来很多问题.

I personally would ditch the drop target on the scroll pane, it's going to cause you to many problems.

你的 drop 方法有点古怪...

Your drop method is a little queezy...

这是个坏主意……

List fileList = null;
try {
    fileList = (List) t
        .getTransferData(DataFlavor.javaFileListFlavor);
} catch (UnsupportedFlavorException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
File f = (File) fileList.get(0);
table.setValueAt(f.getAbsolutePath(), row, column);
table.setValueAt(f.length(), row, column + 1);

基本上，您尝试从可转移文件中提取文件列表，无论操作成功与否，您都尝试使用它?！您根本没有验证返回的值...

Basically, you try and extract the file list from the transferable, and regardless of the success of the operation, you try and use it ?! You do no validation of the returned value at all...

您的放置代码通常并不真正关心放置发生在哪一列，因为您已经有名称和大小列，所以我实际上完全忽略了这一点.

Your drop code generally doesn't really care about what column the drop occurred on, as you have name and size columns already, so I'd actually ignore that altogether.

至于行，现在你有两个选择.当用户没有放在现有行上时，您要么添加新行，要么拒绝尝试.

As for the row, now you have two choices. Either you add a new row when the user doesn't drop on an existing one or you reject the attempt.

(或拒绝不调用现有行的拖动)

(Or reject drags that don't call over an existing row)

要在用户拖动时拒绝操作，你需要重写 dragOver 方法...

To reject the operation while the user is dragging, you need to override the dragOver method...

@Override
public synchronized void dragOver(DropTargetDragEvent dtde) {
    Point point = dtde.getLocation();
    int row = table.rowAtPoint(point);
    if (row < 0) {
        dtde.rejectDrag();
        table.clearSelection();
    } else {
        dtde.acceptDrag(DnDConstants.ACTION_COPY_OR_MOVE);
        table.setRowSelectionInterval(row, row);
    }
}

现在，我在这里有点聪明(而且不是聪明的方式).基本上，如果用户拖过一行，我会突出显示它.这使得下降的去向更加明显.

Now, I'm been a little smart here (and not in the clever way). Basically, if the user has dragged over a row, I've highlighted it. This makes it a little more obvious where the drop is going.

在你的 drop 方法中，我还会做一些额外的检查......

In your drop method, I would also make some additional checks...

@Override
public synchronized void drop(DropTargetDropEvent dtde) {    
    Point point = dtde.getLocation();
    int row = table.rowAtPoint(point);
    if (row >= 0) {
        if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
            dtde.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
            Transferable t = dtde.getTransferable();
            List fileList = null;
            try {
                fileList = (List) t.getTransferData(DataFlavor.javaFileListFlavor);
                if (fileList.size() > 0) {
                    table.clearSelection();
                    Point point = dtde.getLocation();
                    int row = table.rowAtPoint(point);
                    DefaultTableModel model = (DefaultTableModel) table.getModel();
                    model.setValueAt(f.getAbsolutePath(), row, 0);
                    model.setValueAt(f.length(), row, 2);
                }
            } catch (UnsupportedFlavorException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else {
            dtde.rejectDrop();
        }
    } else {
        dtde.rejectDrop();
    }
}

接受 Drag 的表外"

这个过程相对来说是一样的，除了现在我们可以抛弃那些原本会导致我们拒绝拖放的条件(显然)

Accept Drag's "outside" of the table

The process is relativly the same, except now we can throw away the conditions that would have otherwise caused us to reject the drag/drop (obviously)

@Override
public synchronized void dragOver(DropTargetDragEvent dtde) {
    Point point = dtde.getLocation();
    int row = table.rowAtPoint(point);
    if (row < 0) {
        table.clearSelection();
    } else {
        table.setRowSelectionInterval(row, row);
    }
    dtde.acceptDrag(DnDConstants.ACTION_COPY_OR_MOVE);
}

还有drop方法

@Override
public synchronized void drop(DropTargetDropEvent dtde) {    
    if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
        dtde.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
        Transferable t = dtde.getTransferable();
        List fileList = null;
        try {
            fileList = (List) t.getTransferData(DataFlavor.javaFileListFlavor);
            if (fileList.size() > 0) {
                table.clearSelection();
                Point point = dtde.getLocation();
                int row = table.rowAtPoint(point);
                DefaultTableModel model = (DefaultTableModel) table.getModel();
                for (Object value : fileList) {
                    if (value instanceof File) {
                        File f = (File) value;
                        if (row < 0) {
                            System.out.println("addRow");
                            model.addRow(new Object[]{f.getAbsolutePath(), "", f.length(), "", ""});
                        } else {
                            System.out.println("insertRow " + row);
                            model.insertRow(row, new Object[]{f.getAbsolutePath(), "", f.length(), "", ""});
                            row++;
                        }
                    }
                }
            }
        } catch (UnsupportedFlavorException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    } else {
        dtde.rejectDrop();
    }
}

注意.这将在放置点插入行，将所有现有行向下推，或者如果没有放在现有行上，则将它们添加到末尾...

Note. This will insert rows at the drop point, push all the existing rows down OR if not dropped on an existing row, will add them to the end...

测试代码

这是我用来测试代码的完整运行示例...

This a full running example I used to test the code...

public class DropTable {

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

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

                JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new DropPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }

        });
    }

    public class DropPane extends JPanel {

        private JTable table;
        private JScrollPane scroll;
        private DefaultTableModel tm = new DefaultTableModel(new String[]{"File", "File Type", "Size", "Status"}, 0);

        public DropPane() {
            table = new JTable();
            table.setShowGrid(true);
            table.setShowHorizontalLines(true);
            table.setShowVerticalLines(true);
            table.setGridColor(Color.GRAY);

            table.setModel(tm);
            table.setFillsViewportHeight(true);
            table.setPreferredSize(new Dimension(500, 300));

            scroll = new JScrollPane(table);

            table.setDropTarget(new DropTarget() {
                @Override
                public synchronized void dragOver(DropTargetDragEvent dtde) {
                    Point point = dtde.getLocation();
                    int row = table.rowAtPoint(point);
                    if (row < 0) {
                        table.clearSelection();
                    } else {
                        table.setRowSelectionInterval(row, row);
                    }
                    dtde.acceptDrag(DnDConstants.ACTION_COPY_OR_MOVE);
                }

                @Override
                public synchronized void drop(DropTargetDropEvent dtde) {
                    if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                        dtde.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
                        Transferable t = dtde.getTransferable();
                        List fileList = null;
                        try {
                            fileList = (List) t.getTransferData(DataFlavor.javaFileListFlavor);
                            if (fileList.size() > 0) {
                                table.clearSelection();
                                Point point = dtde.getLocation();
                                int row = table.rowAtPoint(point);
                                DefaultTableModel model = (DefaultTableModel) table.getModel();
                                for (Object value : fileList) {
                                    if (value instanceof File) {
                                        File f = (File) value;
                                        if (row < 0) {
                                            model.addRow(new Object[]{f.getAbsolutePath(), "", f.length(), "", ""});
                                        } else {
                                            model.insertRow(row, new Object[]{f.getAbsolutePath(), "", f.length(), "", ""});
                                            row++;
                                        }
                                    }
                                }
                            }
                        } catch (UnsupportedFlavorException e) {
                            e.printStackTrace();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    } else {
                        dtde.rejectDrop();
                    }
                }

            });

            add(scroll, BorderLayout.CENTER);
        }
    }
}

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