我在 JScrollPane 的视口中使用第二个 JTable 来为主表构建 RowHeader。主表上的 DragAndDrop 被禁用。在行头表上启用了 DnD。
如果用户启动了对行标题的拖动，我想将绘制的行标题下拉线（图像中的黑线）扩展到主表（如图像中的绿线）。
有人对我有什么建议吗？
这是SSCCE：
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.datatransfer.StringSelection;
import java.awt.datatransfer.Transferable;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.DropMode;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JViewport;
import javax.swing.TransferHandler;
import javax.swing.UIManager;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.JTableHeader;
import javax.swing.table.TableColumn;
public class DNDLinePainterExampleMain extends JFrame {
public DNDLinePainterExampleMain() {
JTable mainTable = new JTable(4, 3);
mainTable.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
JTable rowTable = new RowHeaderTable(mainTable);
rowTable.setAutoscrolls(true);
rowTable.setDragEnabled(true);
rowTable.setTransferHandler(new RowHeaderTransferHandler());
rowTable.setDropMode(DropMode.INSERT_ROWS);
JScrollPane scrollPane = new JScrollPane(mainTable);
scrollPane.setRowHeaderView(rowTable);
scrollPane.setCorner(JScrollPane.UPPER_LEFT_CORNER,
rowTable.getTableHeader());
this.add(scrollPane);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
JFrame f = new DNDLinePainterExampleMain();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setVisible(true);
}
});
}
/*
* Use a JTable as a renderer for row numbers of a given main table. This
* table must be added to the row header of the scrollpane that contains the
* main table. from:
* http://tips4java.wordpress.com/2008/11/18/row-number-table/
*/
public class RowHeaderTable extends JTable implements ChangeListener,
PropertyChangeListener {
private final JTable table;
public RowHeaderTable(JTable table) {
this.table = table;
table.addPropertyChangeListener(this);
setFocusable(false);
setAutoCreateColumnsFromModel(false);
updateRowHeight();
updateModel();
updateSelectionModel();
TableColumn column = new TableColumn();
column.setHeaderValue("");
addColumn(column);
column.setCellRenderer(new RowNumberRenderer());
getColumnModel().getColumn(0).setPreferredWidth(50);
setPreferredScrollableViewportSize(getPreferredSize());
getTableHeader().setReorderingAllowed(false);
}
@Override
public void addNotify() {
super.addNotify();
Component c = getParent();
// Keep scrolling of the row table in sync with the main table.
if (c instanceof JViewport) {
JViewport viewport = (JViewport) c;
viewport.addChangeListener(this);
}
}
/*
* Delegate method to main table
*/
@Override
public int getRowCount() {
return table.getRowCount();
}
@Override
public int getRowHeight(int row) {
return table.getRowHeight(row);
}
/*
* This table does not use any data from the main TableModel, so just return
* a value based on the row parameter.
*/
@Override
public Object getValueAt(int row, int column) {
return Integer.toString(row + 1);
}
/*
* Don't edit data in the main TableModel by mistake
*/
@Override
public boolean isCellEditable(int row, int column) {
return false;
}
// implements ChangeListener
@Override
public void stateChanged(ChangeEvent e) {
// Keep the scrolling of the row table in sync with main table
JViewport viewport = (JViewport) e.getSource();
JScrollPane scrollPane = (JScrollPane) viewport.getParent();
scrollPane.getVerticalScrollBar().setValue(viewport.getViewPosition().y);
}
// implements PropertyChangeListener
@Override
public void propertyChange(PropertyChangeEvent e) {
// Keep the row table in sync with the main table
if ("rowHeight".equals(e.getPropertyName()))
updateRowHeight();
if ("selectionModel".equals(e.getPropertyName()))
updateSelectionModel();
if ("model".equals(e.getPropertyName()))
updateModel();
}
private void updateRowHeight() {
setRowHeight(table.getRowHeight());
}
private void updateModel() {
setModel(table.getModel());
}
private void updateSelectionModel() {
setSelectionModel(table.getSelectionModel());
}
/*
* Borrow the renderer from JDK1.4.2 table header
*/
private class RowNumberRenderer extends DefaultTableCellRenderer {
public RowNumberRenderer() {
setHorizontalAlignment(JLabel.CENTER);
}
@Override
public Component getTableCellRendererComponent(JTable table,
Object value, boolean isSelected, boolean hasFocus, int row,
int column) {
if (table != null) {
JTableHeader header = table.getTableHeader();
if (header != null) {
setForeground(header.getForeground());
setBackground(header.getBackground());
setFont(header.getFont());
}
}
if (isSelected) {
setFont(getFont().deriveFont(Font.BOLD));
}
setText((value == null) ? "" : value.toString());
setBorder(UIManager.getBorder("TableHeader.cellBorder"));
return this;
}
}//class RowNumberRenderer
}//class RowHeaderTable
public class RowHeaderTransferHandler extends TransferHandler {
@Override
public int getSourceActions(JComponent c) {
return COPY_OR_MOVE;
}
@Override
protected Transferable createTransferable(JComponent c) {
return new StringSelection(c.getName());
}
@Override
public boolean canImport(TransferSupport supp) {
return true;
}
}//class RowHeaderTransferHandler
}//class DNDLinePainterExampleMain
