有人能告诉我我做错了什么吗？我能够使用常规面板进行拖放操作，但现在尝试使用表格，我无法对其进行排序。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。
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);
}
});
}
}
答案 0 :(得分：7)
我个人会抛弃滚动窗格上的放置目标，这会给你带来很多问题。
你的掉落方法有点诡异......
这是一个坏主意......
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transferable中提取文件列表，无论操作成功与否，您都尝试使用它？您根本不会对返回值进行验证...
你的丢弃代码通常并不关心丢弃发生在哪个列上，因为你已经有了名称和大小的列，所以我实际上完全忽略了它。
至于行，现在你有两个选择。当用户没有放弃现有行或拒绝尝试时，您可以添加新行。
（或拒绝不调用现有行的拖动）
要在用户拖动时拒绝操作，您需要覆盖dragOver方法......
@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。这使得下降的位置更加明显。
在你的drop方法中，我还会做一些额外的检查......
@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();
}
}
这个过程是相同的，除了现在我们可以抛弃原本会导致我们拒绝拖放的条件（显然）
@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);
}
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();
}
}
请注意。这将在drop point处插入行，将所有现有行向下推或如果未在现有行上删除，则将它们添加到结尾...
测试代码
这是一个用于测试代码的完整运行示例...
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);
}
}
}