我正在开发一个必须计算JTable宽度和高度的应用程序，如果在运行时以及调整列宽后更改了模型数据，则无法正确计算宽度和列。以下是示例代码：-
**
SimpleTableDemo.java
**
package com.swing.data;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.TableModel;
public class SimpleTableDemo extends JPanel implements ActionListener {
private boolean DEBUG = false;
private JTable table = null;
private TableColumnAdjuster app = null;
String[] columnNames = {"First Name",
"Last Name",
"Sport",
"# of Years",
"Vegetarian"};
Object[][] data = {
{"Kathy", "Smith",
"Snowboarding", new Integer(5), new Boolean(false)},
{"John", "Doe",
"Rowing", new Integer(3), new Boolean(true)},
{"Sue", "Black",
"Knitting", new Integer(2), new Boolean(false)},
{"Jane", "White",
"Speed reading", new Integer(20), new Boolean(true)},
{"Joe", "Brown",
"Pool", new Integer(10), new Boolean(false)}
};
CutomTableCellRenderer renderer = null;
public SimpleTableDemo() {
super(new GridLayout(1,0));
table = new JTable(data, columnNames);
table.setPreferredScrollableViewportSize(new Dimension(500, 70));
table.setFillsViewportHeight(true);
if (DEBUG) {
table.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
printDebugData(table);
}
});
}
renderer = new CutomTableCellRenderer(table.getDefaultRenderer(Object.class));
table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
table.setDefaultRenderer(Object.class, renderer);
//table.setSelectionMode(JTable.AUTO_RESIZE_SUBSEQUENT_COLUMNS);
JScrollPane scrollPane = new JScrollPane(table);
app = new TableColumnAdjuster(table);
app.adjustColumns();
// scrollPane.setRowHeaderView(jRowTable);
//scrollPane.setCorner(JScrollPane.UPPER_LEFT_CORNER,jRowTable.getTableHeader());
//scrollPane.setSize(300,300);
//Create the scroll pane and add the table to it.
//Add the scroll pane to this panel.
add(scrollPane);
JButton button = new JButton("Change");
add(button);
button.addActionListener(this);
}
private void printDebugData(JTable table) {
int numRows = table.getRowCount();
int numCols = table.getColumnCount();
javax.swing.table.TableModel model = table.getModel();
System.out.println("Value of data: ");
for (int i=0; i < numRows; i++) {
System.out.print(" row " + i + ":");
for (int j=0; j < numCols; j++) {
System.out.print(" " + model.getValueAt(i, j));
}
System.out.println();
}
System.out.println("--------------------------");
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event-dispatching thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("SimpleTableDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Create and set up the content pane.
SimpleTableDemo newContentPane = new SimpleTableDemo();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
//Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
@Override
public void actionPerformed(ActionEvent e) {
renderer.setText("Modified.............................");
app.adjustColumns();
System.out.println("tableWidth:" + table.getWidth() + "tableHeight:" + table.getHeight());
}
}
**
TableColumnAdjuster.java
**
package com.swing.data;
import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;
/*
* Class to manage the widths of colunmns in a table.
*
* Various properties control how the width of the column is calculated.
* Another property controls whether column width calculation should be dynamic.
* Finally, various Actions will be added to the table to allow the user
* to customize the functionality.
*
* This class was designed to be used with tables that use an auto resize mode
* of AUTO_RESIZE_OFF. With all other modes you are constrained as the width
* of the columns must fit inside the table. So if you increase one column, one
* or more of the other columns must decrease. Because of this the resize mode
* of RESIZE_ALL_COLUMNS will work the best.
*/
public class TableColumnAdjuster implements PropertyChangeListener, TableModelListener
{
private JTable table;
private int spacing;
private boolean isColumnHeaderIncluded;
private boolean isColumnDataIncluded;
private boolean isOnlyAdjustLarger;
private boolean isDynamicAdjustment;
private Map<TableColumn, Integer> columnSizes = new HashMap<TableColumn, Integer>();
/*
* Specify the table and use default spacing
*/
public TableColumnAdjuster(JTable table)
{
this(table, 6);
}
/*
* Specify the table and spacing
*/
public TableColumnAdjuster(JTable table, int spacing)
{
this.table = table;
this.spacing = spacing;
setColumnHeaderIncluded( true );
setColumnDataIncluded( true );
setOnlyAdjustLarger( true );
setDynamicAdjustment( false );
installActions();
}
/*
* Adjust the widths of all the columns in the table
*/
public void adjustColumns()
{
TableColumnModel tcm = table.getColumnModel();
for (int i = 0; i < tcm.getColumnCount(); i++)
{
adjustColumn(i);
}
}
/*
* Adjust the width of the specified column in the table
*/
public void adjustColumn(final int column)
{
TableColumn tableColumn = table.getColumnModel().getColumn(column);
if (! tableColumn.getResizable()) return;
int columnHeaderWidth = getColumnHeaderWidth( column );
int columnDataWidth = getColumnDataWidth( column );
int preferredWidth = Math.max(columnHeaderWidth, columnDataWidth);
updateTableColumn(column, preferredWidth);
}
/*
* Calculated the width based on the column name
*/
private int getColumnHeaderWidth(int column)
{
if (! isColumnHeaderIncluded) return 0;
TableColumn tableColumn = table.getColumnModel().getColumn(column);
Object value = tableColumn.getHeaderValue();
TableCellRenderer renderer = tableColumn.getHeaderRenderer();
if (renderer == null)
{
renderer = table.getTableHeader().getDefaultRenderer();
}
Component c = renderer.getTableCellRendererComponent(table, value, false, false, -1, column);
return c.getPreferredSize().width;
}
/*
* Calculate the width based on the widest cell renderer for the
* given column.
*/
private int getColumnDataWidth(int column)
{
if (! isColumnDataIncluded) return 0;
int preferredWidth = 0;
int maxWidth = table.getColumnModel().getColumn(column).getMaxWidth();
for (int row = 0; row < table.getRowCount(); row++)
{
preferredWidth = Math.max(preferredWidth, getCellDataWidth(row, column));
// We've exceeded the maximum width, no need to check other rows
if (preferredWidth >= maxWidth)
break;
}
return preferredWidth;
}
/*
* Get the preferred width for the specified cell
*/
private int getCellDataWidth(int row, int column)
{
// Inovke the renderer for the cell to calculate the preferred width
TableCellRenderer cellRenderer = table.getCellRenderer(row, column);
Component c = table.prepareRenderer(cellRenderer, row, column);
int width = c.getPreferredSize().width + table.getIntercellSpacing().width;
return width;
}
/*
* Update the TableColumn with the newly calculated width
*/
private void updateTableColumn(int column, int width)
{
final TableColumn tableColumn = table.getColumnModel().getColumn(column);
if (! tableColumn.getResizable()) return;
width += spacing;
// Don't shrink the column width
if (isOnlyAdjustLarger)
{
width = Math.max(width, tableColumn.getPreferredWidth());
}
columnSizes.put(tableColumn, new Integer(tableColumn.getWidth()));
table.getTableHeader().setResizingColumn(tableColumn);
tableColumn.setWidth(width);
}
/*
* Restore the widths of the columns in the table to its previous width
*/
public void restoreColumns()
{
TableColumnModel tcm = table.getColumnModel();
for (int i = 0; i < tcm.getColumnCount(); i++)
{
restoreColumn(i);
}
}
/*
* Restore the width of the specified column to its previous width
*/
private void restoreColumn(int column)
{
TableColumn tableColumn = table.getColumnModel().getColumn(column);
Integer width = columnSizes.get(tableColumn);
if (width != null)
{
table.getTableHeader().setResizingColumn(tableColumn);
tableColumn.setWidth( width.intValue() );
}
}
/*
* Indicates whether to include the header in the width calculation
*/
public void setColumnHeaderIncluded(boolean isColumnHeaderIncluded)
{
this.isColumnHeaderIncluded = isColumnHeaderIncluded;
}
/*
* Indicates whether to include the model data in the width calculation
*/
public void setColumnDataIncluded(boolean isColumnDataIncluded)
{
this.isColumnDataIncluded = isColumnDataIncluded;
}
/*
* Indicates whether columns can only be increased in size
*/
public void setOnlyAdjustLarger(boolean isOnlyAdjustLarger)
{
this.isOnlyAdjustLarger = isOnlyAdjustLarger;
}
/*
* Indicate whether changes to the model should cause the width to be
* dynamically recalculated.
*/
public void setDynamicAdjustment(boolean isDynamicAdjustment)
{
// May need to add or remove the TableModelListener when changed
if (this.isDynamicAdjustment != isDynamicAdjustment)
{
if (isDynamicAdjustment)
{
table.addPropertyChangeListener( this );
table.getModel().addTableModelListener( this );
}
else
{
table.removePropertyChangeListener( this );
table.getModel().removeTableModelListener( this );
}
}
this.isDynamicAdjustment = isDynamicAdjustment;
}
//
// Implement the PropertyChangeListener
//
public void propertyChange(PropertyChangeEvent e)
{
// When the TableModel changes we need to update the listeners
// and column widths
if ("model".equals(e.getPropertyName()))
{
TableModel model = (TableModel)e.getOldValue();
model.removeTableModelListener( this );
model = (TableModel)e.getNewValue();
model.addTableModelListener( this );
adjustColumns();
}
}
//
// Implement the TableModelListener
//
public void tableChanged(TableModelEvent e)
{
if (! isColumnDataIncluded) return;
// A cell has been updated
if (e.getType() == TableModelEvent.UPDATE)
{
int column = table.convertColumnIndexToView(e.getColumn());
// Only need to worry about an increase in width for this cell
if (isOnlyAdjustLarger)
{
int row = e.getFirstRow();
TableColumn tableColumn = table.getColumnModel().getColumn(column);
if (tableColumn.getResizable())
{
int width = getCellDataWidth(row, column);
updateTableColumn(column, width);
}
}
// Could be an increase of decrease so check all rows
else
{
adjustColumn( column );
}
}
// The update affected more than one column so adjust all columns
else
{
adjustColumns();
}
}
/*
* Install Actions to give user control of certain functionality.
*/
private void installActions()
{
installColumnAction(true, true, "adjustColumn", "control ADD");
installColumnAction(false, true, "adjustColumns", "control shift ADD");
installColumnAction(true, false, "restoreColumn", "control SUBTRACT");
installColumnAction(false, false, "restoreColumns", "control shift SUBTRACT");
installToggleAction(true, false, "toggleDynamic", "control MULTIPLY");
installToggleAction(false, true, "toggleLarger", "control DIVIDE");
}
/*
* Update the input and action maps with a new ColumnAction
*/
private void installColumnAction(
boolean isSelectedColumn, boolean isAdjust, String key, String keyStroke)
{
Action action = new ColumnAction(isSelectedColumn, isAdjust);
KeyStroke ks = KeyStroke.getKeyStroke( keyStroke );
table.getInputMap().put(ks, key);
table.getActionMap().put(key, action);
}
/*
* Update the input and action maps with new ToggleAction
*/
private void installToggleAction(
boolean isToggleDynamic, boolean isToggleLarger, String key, String keyStroke)
{
Action action = new ToggleAction(isToggleDynamic, isToggleLarger);
KeyStroke ks = KeyStroke.getKeyStroke( keyStroke );
table.getInputMap().put(ks, key);
table.getActionMap().put(key, action);
}
/*
* Action to adjust or restore the width of a single column or all columns
*/
class ColumnAction extends AbstractAction
{
private boolean isSelectedColumn;
private boolean isAdjust;
public ColumnAction(boolean isSelectedColumn, boolean isAdjust)
{
this.isSelectedColumn = isSelectedColumn;
this.isAdjust = isAdjust;
}
@Override
public void actionPerformed(ActionEvent e)
{
// Handle selected column(s) width change actions
if (isSelectedColumn)
{
int[] columns = table.getSelectedColumns();
for (int i = 0; i < columns.length; i++)
{
if (isAdjust)
adjustColumn(columns[i]);
else
restoreColumn(columns[i]);
}
}
else
{
if (isAdjust)
adjustColumns();
else
restoreColumns();
}
}
}
/*
* Toggle properties of the TableColumnAdjuster so the user can
* customize the functionality to their preferences
*/
class ToggleAction extends AbstractAction
{
private boolean isToggleDynamic;
private boolean isToggleLarger;
public ToggleAction(boolean isToggleDynamic, boolean isToggleLarger)
{
this.isToggleDynamic = isToggleDynamic;
this.isToggleLarger = isToggleLarger;
}
@Override
public void actionPerformed(ActionEvent e)
{
if (isToggleDynamic)
{
setDynamicAdjustment(! isDynamicAdjustment);
return;
}
if (isToggleLarger)
{
setOnlyAdjustLarger(! isOnlyAdjustLarger);
return;
}
}
}
}
**
CutomTableCellRenderer.java
**
package com.swing.data;
import java.awt.Color;
import java.awt.Component;
import javax.swing.JLabel;
import javax.swing.JTable;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.TableCellRenderer;
public class CutomTableCellRenderer extends DefaultTableCellRenderer
{
private TableCellRenderer mWrappedRenderer;
private String text = "Original";
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
public CutomTableCellRenderer(TableCellRenderer pWrappedRenderer) {
mWrappedRenderer = pWrappedRenderer;
}
public Component getTableCellRendererComponent
(JTable table, Object value, boolean isSelected,
boolean hasFocus, int row, int column)
{
Component cell = mWrappedRenderer.getTableCellRendererComponent(table, value, isSelected,
hasFocus, row, column);
if( row == 1 )
{
JLabel label = (JLabel)cell;
label.setText(text);
}
else
{
cell.setBackground( Color.white );
}
return cell;
}
}
通过上面的代码，模型中的实际数据不会更改。但是，第一次单击更改按钮时，表的宽度和高度计算不正确。下次更改时，将显示修改后的表格宽度和高度。我对此很陌生。
如果从单元格更改了数据，如何检索JTable的实际宽度和高度
渲染器？
如何正确计算桌子的宽度和高度。
最佳答案
在ActionListener的代码中，
renderer.setText("Modified.............................");
app.adjustColumns();
System.out.println("tableWidth:" + table.getWidth() + "tableHeight:" + table.getHeight());
对
app.adjustColumns()的调用仅触发新布局，仅在事件完成后（即在完成方法并写入输出之后），可见调整后的列。您可以通过将输出封装到另一个事件中来轻松验证它：
System.out.println("PRE tableWidth:" + table.getWidth() + "tableHeight:" + table.getHeight());
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
System.out.println("POST tableWidth:" + table.getWidth() + "tableHeight:" + table.getHeight());
}
});
产生
PRE tableWidth:390tableHeight:80
POST tableWidth:710tableHeight:80