Java Tutorial/Swing Event/ComponentListener
Содержание
A ComponentAdapter.
<source lang="java">
import java.awt.event.ruponentAdapter; import java.awt.event.ruponentEvent; import javax.swing.JFrame; class MoveAdapter extends ComponentAdapter {
public void componentMoved(ComponentEvent e) {
int x = e.getComponent().getX();
int y = e.getComponent().getY();
System.out.println("x: " + x);
System.out.println("y: " + y);
}
} public class Adapter {
public static void main(String[] args) {
JFrame f = new JFrame();
f.addComponentListener(new MoveAdapter());
f.setSize(310, 200);
f.setLocationRelativeTo(null);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
}</source>
A position of a window on the screen.
<source lang="java">
import java.awt.event.ruponentEvent; import java.awt.event.ruponentListener; import javax.swing.JFrame; public class MovingWindow extends JFrame implements ComponentListener {
public MovingWindow() {
addComponentListener(this);
setSize(310, 200);
setLocationRelativeTo(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
public void componentResized(ComponentEvent e) {
}
public void componentMoved(ComponentEvent e) {
int x = e.getComponent().getX();
int y = e.getComponent().getY();
System.out.println("x: " + x);
System.out.println("y: " + y);
}
public void componentShown(ComponentEvent e) {
}
public void componentHidden(ComponentEvent e) {
}
public static void main(String[] args) {
new MovingWindow();
}
}</source>
ComponentListener and ComponentEvent
<source lang="java">
/*
* Copyright (c) 1995 - 2008 Sun Microsystems, Inc. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of Sun Microsystems nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
/*
* ComponentEventDemo.java requires no other files. */
import java.awt.BorderLayout; import java.awt.Dimension; import java.awt.event.ruponentEvent; import java.awt.event.ruponentListener; import java.awt.event.ItemEvent; import java.awt.event.ItemListener; import javax.swing.JCheckBox; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTextArea; public class ComponentEventDemo extends JPanel implements ComponentListener,
ItemListener {
static JFrame frame;
JTextArea display;
JLabel label;
String newline = "\n";
public ComponentEventDemo() {
super(new BorderLayout());
display = new JTextArea();
display.setEditable(false);
JScrollPane scrollPane = new JScrollPane(display);
scrollPane.setPreferredSize(new Dimension(350, 200));
JPanel panel = new JPanel(new BorderLayout());
label = new JLabel("This is a label", JLabel.CENTER);
label.addComponentListener(this);
panel.add(label, BorderLayout.CENTER);
JCheckBox checkbox = new JCheckBox("Label visible", true);
checkbox.addItemListener(this);
checkbox.addComponentListener(this);
panel.add(checkbox, BorderLayout.PAGE_END);
panel.addComponentListener(this);
add(scrollPane, BorderLayout.CENTER);
add(panel, BorderLayout.PAGE_END);
frame.addComponentListener(this);
}
public void itemStateChanged(ItemEvent e) {
if (e.getStateChange() == ItemEvent.SELECTED) {
label.setVisible(true);
// Need to revalidate and repaint, or else the label
// will probably be drawn in the wrong place.
label.revalidate();
label.repaint();
} else {
label.setVisible(false);
}
}
protected void displayMessage(String message) {
// If the text area is not yet realized, and
// we tell it to draw text, it could cause
// a text/AWT tree deadlock. Our solution is
// to ensure that the text area is realized
// before attempting to draw text.
// if (display.isShowing()) {
display.append(message + newline);
display.setCaretPosition(display.getDocument().getLength());
// }
}
public void componentHidden(ComponentEvent e) {
displayMessage(e.getComponent().getClass().getName() + " --- Hidden");
}
public void componentMoved(ComponentEvent e) {
displayMessage(e.getComponent().getClass().getName() + " --- Moved");
}
public void componentResized(ComponentEvent e) {
displayMessage(e.getComponent().getClass().getName() + " --- Resized ");
}
public void componentShown(ComponentEvent e) {
displayMessage(e.getComponent().getClass().getName() + " --- Shown");
}
/**
* 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.
frame = new JFrame("ComponentEventDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Create and set up the content pane.
JComponent newContentPane = new ComponentEventDemo();
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();
}
});
}
}</source>
extends ComponentAdapter
<source lang="java">
import java.awt.BorderLayout; import java.awt.Point; import java.awt.event.ruponentAdapter; import java.awt.event.ruponentEvent; import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.JViewport; import javax.swing.SwingUtilities; import javax.swing.table.AbstractTableModel; public class RowAdder extends JFrame {
SimpleModel tableData = new SimpleModel();
JTable table = new JTable(tableData);
public static void main(String[] args) {
RowAdder ra = new RowAdder();
ra.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ra.setSize(400, 300);
ra.setVisible(true);
}
public RowAdder() {
setLayout(new BorderLayout());
table.addComponentListener(new TableScroller());
add(new JScrollPane(table), BorderLayout.CENTER);
}
class TableScroller extends ComponentAdapter {
public void componentResized(ComponentEvent event) {
int lastRow = tableData.getRowCount() - 1;
int cellTop = table.getCellRect(lastRow, 0, true).y;
JScrollPane jsp = (JScrollPane) SwingUtilities.getAncestorOfClass(
JScrollPane.class, table);
JViewport jvp = jsp.getViewport();
int portHeight = jvp.getSize().height;
int position = cellTop
- (portHeight - table.getRowHeight() - table.getRowMargin());
if (position >= 0) {
jvp.setViewPosition(new Point(0, position));
}
}
}
} class SimpleModel extends AbstractTableModel {
public void addText(String text) {
fireTableDataChanged();
}
public int getRowCount() {
return 100;
}
public int getColumnCount() {
return 3;
}
public Object getValueAt(int row, int column) {
return row+" "+column;
}
}</source>
How to Write a Component Listener
One or more component events are fired after the component is hidden, made visible, moved, or resized.
<source lang="java">
import java.awt.ruponent; import java.awt.event.ruponentEvent; import java.awt.event.ruponentListener; import javax.swing.JCheckBox; import javax.swing.JFrame; public class UsingComponentListener {
public static void main(String[] a) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JCheckBox checkbox = new JCheckBox("Label visible", true);
checkbox.addComponentListener(new ComponentListener() {
public void componentHidden(ComponentEvent e) {
System.out.println("componentHidden event from " + e.getComponent().getClass().getName());
}
public void componentMoved(ComponentEvent e) {
Component c = e.getComponent();
System.out.println("componentMoved event from " + c.getClass().getName()
+ "; new location: " + c.getLocation().x + ", " + c.getLocation().y);
}
public void componentResized(ComponentEvent e) {
Component c = e.getComponent();
System.out.println("componentResized event from " + c.getClass().getName() + "; new size: "
+ c.getSize().width + ", " + c.getSize().height);
}
public void componentShown(ComponentEvent e) {
System.out.println("componentShown event from " + e.getComponent().getClass().getName());
}
});
frame.add(checkbox, "North");
frame.setSize(300, 200);
frame.setVisible(true);
}
}</source>
Installs/resets a ComponentListener to resize the given window to minWidth/Height if needed
<source lang="java">
/*
* $Id: WindowUtils.java,v 1.16 2009/05/25 16:37:52 kschaefe Exp $ * * Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle, * Santa Clara, California 95054, U.S.A. All rights reserved. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
import java.awt.Window; import java.awt.event.ruponentAdapter; import java.awt.event.ruponentListener; import javax.swing.SwingUtilities; public class Utils {
/**
* Installs/resets a ComponentListener to resize the
* given window to minWidth/Height if needed.
*
* @param window
* @param minWidth
* @param minHeight
*/
public static void setMinimumSizeManager(Window window, int minWidth,
int minHeight) {
ComponentListener[] listeners = window.getComponentListeners();
ComponentListener listener = null;
for (ComponentListener l : listeners) {
if (l instanceof MinSizeComponentListener) {
listener = l;
break;
}
}
if (listener == null) {
window.addComponentListener(new MinSizeComponentListener(
window, minWidth, minHeight));
} else {
((MinSizeComponentListener) listener).resetSizes(minWidth,
minHeight);
}
}
/**
* Resets window size to minSize if needed.
*
* @author Patrick Wright
*/
public static class MinSizeComponentListener extends ComponentAdapter {
private Window window;
private int minHeight;
private int minWidth;
MinSizeComponentListener(Window frame, int minWidth, int minHeight) {
this.window = frame;
resetSizes(minWidth, minHeight);
}
public void resetSizes(int minWidth, int minHeight) {
this.minWidth = minWidth;
this.minHeight = minHeight;
adjustIfNeeded(window);
}
@Override
public void componentResized(java.awt.event.ruponentEvent evt) {
adjustIfNeeded((Window) evt.getComponent());
}
private void adjustIfNeeded(final Window window) {
boolean doSize = false;
int newWidth = window.getWidth();
int newHeight = window.getHeight();
if (newWidth < minWidth) {
newWidth = minWidth;
doSize = true;
}
if (newHeight < minHeight) {
newHeight = minHeight;
doSize = true;
}
if (doSize) {
final int w = newWidth;
final int h = newHeight;
SwingUtilities.invokeLater(new Runnable() {
public void run() {
window.setSize(w, h);
}
});
}
}
}
}</source>
