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The JApplet.java Java example source code
/*
* Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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 General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.swing;
import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
import java.beans.PropertyChangeListener;
import java.util.Locale;
import java.util.Vector;
import java.io.Serializable;
import javax.accessibility.*;
/**
* An extended version of <code>java.applet.Applet that adds support for
* the JFC/Swing component architecture.
* You can find task-oriented documentation about using <code>JApplet
* in <em>The Java Tutorial,
* in the section
* <a
href="http://docs.oracle.com/javase/tutorial/uiswing/components/applet.html">How to Make Applets</a>.
* <p>
* The <code>JApplet class is slightly incompatible with
* <code>java.applet.Applet. JApplet contains a
* <code>JRootPane as its only child. The contentPane
* should be the parent of any children of the <code>JApplet.
* As a convenience, the {@code add}, {@code remove}, and {@code setLayout}
* methods of this class are overridden, so that they delegate calls
* to the corresponding methods of the {@code ContentPane}.
* For example, you can add a child component to an applet as follows:
* <pre>
* applet.add(child);
* </pre>
*
* And the child will be added to the <code>contentPane.
* The <code>contentPane will always be non-null.
* Attempting to set it to <code>null will cause the
* <code>JApplet to throw an exception. The default
* <code>contentPane will have a BorderLayout
* manager set on it.
* Refer to {@link javax.swing.RootPaneContainer}
* for details on adding, removing and setting the <code>LayoutManager
* of a <code>JApplet.
* <p>
* Please see the <code>JRootPane documentation for a
* complete description of the <code>contentPane, glassPane,
* and <code>layeredPane properties.
* <p>
* <strong>Warning: Swing is not thread safe. For more
* information see <a
* href="package-summary.html#threading">Swing's Threading
* Policy</a>.
* <p>
* <strong>Warning:
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing. As of 1.4, support for long term storage
* of all JavaBeans™
* has been added to the <code>java.beans package.
* Please see {@link java.beans.XMLEncoder}.
*
* @see javax.swing.RootPaneContainer
* @beaninfo
* attribute: isContainer true
* attribute: containerDelegate getContentPane
* description: Swing's Applet subclass.
*
* @author Arnaud Weber
*/
public class JApplet extends Applet implements Accessible,
RootPaneContainer,
TransferHandler.HasGetTransferHandler
{
/**
* @see #getRootPane
* @see #setRootPane
*/
protected JRootPane rootPane;
/**
* If true then calls to <code>add and setLayout
* will be forwarded to the <code>contentPane. This is initially
* false, but is set to true when the <code>JApplet is constructed.
*
* @see #isRootPaneCheckingEnabled
* @see #setRootPaneCheckingEnabled
* @see javax.swing.RootPaneContainer
*/
protected boolean rootPaneCheckingEnabled = false;
/**
* The <code>TransferHandler for this applet.
*/
private TransferHandler transferHandler;
/**
* Creates a swing applet instance.
* <p>
* This constructor sets the component's locale property to the value
* returned by <code>JComponent.getDefaultLocale.
*
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
* @see JComponent#getDefaultLocale
*/
public JApplet() throws HeadlessException {
super();
// Check the timerQ and restart if necessary.
TimerQueue q = TimerQueue.sharedInstance();
if(q != null) {
q.startIfNeeded();
}
/* Workaround for bug 4155072. The shared double buffer image
* may hang on to a reference to this applet; unfortunately
* Image.getGraphics() will continue to call JApplet.getForeground()
* and getBackground() even after this applet has been destroyed.
* So we ensure that these properties are non-null here.
*/
setForeground(Color.black);
setBackground(Color.white);
setLocale( JComponent.getDefaultLocale() );
setLayout(new BorderLayout());
setRootPane(createRootPane());
setRootPaneCheckingEnabled(true);
setFocusTraversalPolicyProvider(true);
sun.awt.SunToolkit.checkAndSetPolicy(this);
enableEvents(AWTEvent.KEY_EVENT_MASK);
}
/** Called by the constructor methods to create the default rootPane. */
protected JRootPane createRootPane() {
JRootPane rp = new JRootPane();
// NOTE: this uses setOpaque vs LookAndFeel.installProperty as there
// is NO reason for the RootPane not to be opaque. For painting to
// work the contentPane must be opaque, therefor the RootPane can
// also be opaque.
rp.setOpaque(true);
return rp;
}
/**
* Sets the {@code transferHandler} property, which is a mechanism to
* support transfer of data into this component. Use {@code null}
* if the component does not support data transfer operations.
* <p>
* If the system property {@code suppressSwingDropSupport} is {@code false}
* (the default) and the current drop target on this component is either
* {@code null} or not a user-set drop target, this method will change the
* drop target as follows: If {@code newHandler} is {@code null} it will
* clear the drop target. If not {@code null} it will install a new
* {@code DropTarget}.
* <p>
* Note: When used with {@code JApplet}, {@code TransferHandler} only
* provides data import capability, as the data export related methods
* are currently typed to {@code JComponent}.
* <p>
* Please see
* <a href="http://docs.oracle.com/javase/tutorial/uiswing/dnd/index.html">
* How to Use Drag and Drop and Data Transfer</a>, a section in
* <em>The Java Tutorial, for more information.
*
* @param newHandler the new {@code TransferHandler}
*
* @see TransferHandler
* @see #getTransferHandler
* @see java.awt.Component#setDropTarget
* @since 1.6
*
* @beaninfo
* bound: true
* hidden: true
* description: Mechanism for transfer of data into the component
*/
public void setTransferHandler(TransferHandler newHandler) {
TransferHandler oldHandler = transferHandler;
transferHandler = newHandler;
SwingUtilities.installSwingDropTargetAsNecessary(this, transferHandler);
firePropertyChange("transferHandler", oldHandler, newHandler);
}
/**
* Gets the <code>transferHandler property.
*
* @return the value of the <code>transferHandler property
*
* @see TransferHandler
* @see #setTransferHandler
* @since 1.6
*/
public TransferHandler getTransferHandler() {
return transferHandler;
}
/**
* Just calls <code>paint(g). This method was overridden to
* prevent an unnecessary call to clear the background.
*/
public void update(Graphics g) {
paint(g);
}
/**
* Sets the menubar for this applet.
* @param menuBar the menubar being placed in the applet
*
* @see #getJMenuBar
*
* @beaninfo
* hidden: true
* description: The menubar for accessing pulldown menus from this applet.
*/
public void setJMenuBar(JMenuBar menuBar) {
getRootPane().setMenuBar(menuBar);
}
/**
* Returns the menubar set on this applet.
*
* @see #setJMenuBar
*/
public JMenuBar getJMenuBar() {
return getRootPane().getMenuBar();
}
/**
* Returns whether calls to <code>add and
* <code>setLayout are forwarded to the contentPane.
*
* @return true if <code>add and setLayout
* are forwarded; false otherwise
*
* @see #addImpl
* @see #setLayout
* @see #setRootPaneCheckingEnabled
* @see javax.swing.RootPaneContainer
*/
protected boolean isRootPaneCheckingEnabled() {
return rootPaneCheckingEnabled;
}
/**
* Sets whether calls to <code>add and
* <code>setLayout are forwarded to the contentPane.
*
* @param enabled true if <code>add and setLayout
* are forwarded, false if they should operate directly on the
* <code>JApplet.
*
* @see #addImpl
* @see #setLayout
* @see #isRootPaneCheckingEnabled
* @see javax.swing.RootPaneContainer
* @beaninfo
* hidden: true
* description: Whether the add and setLayout methods are forwarded
*/
protected void setRootPaneCheckingEnabled(boolean enabled) {
rootPaneCheckingEnabled = enabled;
}
/**
* Adds the specified child <code>Component.
* This method is overridden to conditionally forward calls to the
* <code>contentPane.
* By default, children are added to the <code>contentPane instead
* of the frame, refer to {@link javax.swing.RootPaneContainer} for
* details.
*
* @param comp the component to be enhanced
* @param constraints the constraints to be respected
* @param index the index
* @exception IllegalArgumentException if <code>index is invalid
* @exception IllegalArgumentException if adding the container's parent
* to itself
* @exception IllegalArgumentException if adding a window to a container
*
* @see #setRootPaneCheckingEnabled
* @see javax.swing.RootPaneContainer
*/
protected void addImpl(Component comp, Object constraints, int index)
{
if(isRootPaneCheckingEnabled()) {
getContentPane().add(comp, constraints, index);
}
else {
super.addImpl(comp, constraints, index);
}
}
/**
* Removes the specified component from the container. If
* <code>comp is not the rootPane, this will forward
* the call to the <code>contentPane. This will do nothing if
* <code>comp is not a child of the JFrame or
* <code>contentPane.
*
* @param comp the component to be removed
* @throws NullPointerException if <code>comp is null
* @see #add
* @see javax.swing.RootPaneContainer
*/
public void remove(Component comp) {
if (comp == rootPane) {
super.remove(comp);
} else {
getContentPane().remove(comp);
}
}
/**
* Sets the <code>LayoutManager.
* Overridden to conditionally forward the call to the
* <code>contentPane.
* Refer to {@link javax.swing.RootPaneContainer} for
* more information.
*
* @param manager the <code>LayoutManager
* @see #setRootPaneCheckingEnabled
* @see javax.swing.RootPaneContainer
*/
public void setLayout(LayoutManager manager) {
if(isRootPaneCheckingEnabled()) {
getContentPane().setLayout(manager);
}
else {
super.setLayout(manager);
}
}
/**
* Returns the rootPane object for this applet.
*
* @see #setRootPane
* @see RootPaneContainer#getRootPane
*/
public JRootPane getRootPane() {
return rootPane;
}
/**
* Sets the rootPane property. This method is called by the constructor.
* @param root the rootPane object for this applet
*
* @see #getRootPane
*
* @beaninfo
* hidden: true
* description: the RootPane object for this applet.
*/
protected void setRootPane(JRootPane root) {
if(rootPane != null) {
remove(rootPane);
}
rootPane = root;
if(rootPane != null) {
boolean checkingEnabled = isRootPaneCheckingEnabled();
try {
setRootPaneCheckingEnabled(false);
add(rootPane, BorderLayout.CENTER);
}
finally {
setRootPaneCheckingEnabled(checkingEnabled);
}
}
}
/**
* Returns the contentPane object for this applet.
*
* @see #setContentPane
* @see RootPaneContainer#getContentPane
*/
public Container getContentPane() {
return getRootPane().getContentPane();
}
/**
* Sets the contentPane property. This method is called by the constructor.
* @param contentPane the contentPane object for this applet
*
* @exception java.awt.IllegalComponentStateException (a runtime
* exception) if the content pane parameter is null
* @see #getContentPane
* @see RootPaneContainer#setContentPane
*
* @beaninfo
* hidden: true
* description: The client area of the applet where child
* components are normally inserted.
*/
public void setContentPane(Container contentPane) {
getRootPane().setContentPane(contentPane);
}
/**
* Returns the layeredPane object for this applet.
*
* @exception java.awt.IllegalComponentStateException (a runtime
* exception) if the layered pane parameter is null
* @see #setLayeredPane
* @see RootPaneContainer#getLayeredPane
*/
public JLayeredPane getLayeredPane() {
return getRootPane().getLayeredPane();
}
/**
* Sets the layeredPane property. This method is called by the constructor.
* @param layeredPane the layeredPane object for this applet
*
* @see #getLayeredPane
* @see RootPaneContainer#setLayeredPane
*
* @beaninfo
* hidden: true
* description: The pane which holds the various applet layers.
*/
public void setLayeredPane(JLayeredPane layeredPane) {
getRootPane().setLayeredPane(layeredPane);
}
/**
* Returns the glassPane object for this applet.
*
* @see #setGlassPane
* @see RootPaneContainer#getGlassPane
*/
public Component getGlassPane() {
return getRootPane().getGlassPane();
}
/**
* Sets the glassPane property.
* This method is called by the constructor.
* @param glassPane the glassPane object for this applet
*
* @see #getGlassPane
* @see RootPaneContainer#setGlassPane
*
* @beaninfo
* hidden: true
* description: A transparent pane used for menu rendering.
*/
public void setGlassPane(Component glassPane) {
getRootPane().setGlassPane(glassPane);
}
/**
* {@inheritDoc}
*
* @since 1.6
*/
public Graphics getGraphics() {
JComponent.getGraphicsInvoked(this);
return super.getGraphics();
}
/**
* Repaints the specified rectangle of this component within
* <code>time milliseconds. Refer to RepaintManager
* for details on how the repaint is handled.
*
* @param time maximum time in milliseconds before update
* @param x the <i>x coordinate
* @param y the <i>y coordinate
* @param width the width
* @param height the height
* @see RepaintManager
* @since 1.6
*/
public void repaint(long time, int x, int y, int width, int height) {
if (RepaintManager.HANDLE_TOP_LEVEL_PAINT) {
RepaintManager.currentManager(this).addDirtyRegion(
this, x, y, width, height);
}
else {
super.repaint(time, x, y, width, height);
}
}
/**
* Returns a string representation of this JApplet. This method
* is intended to be used only for debugging purposes, and the
* content and format of the returned string may vary between
* implementations. The returned string may be empty but may not
* be <code>null.
*
* @return a string representation of this JApplet.
*/
protected String paramString() {
String rootPaneString = (rootPane != null ?
rootPane.toString() : "");
String rootPaneCheckingEnabledString = (rootPaneCheckingEnabled ?
"true" : "false");
return super.paramString() +
",rootPane=" + rootPaneString +
",rootPaneCheckingEnabled=" + rootPaneCheckingEnabledString;
}
/////////////////
// Accessibility support
////////////////
protected AccessibleContext accessibleContext = null;
/**
* Gets the AccessibleContext associated with this JApplet.
* For JApplets, the AccessibleContext takes the form of an
* AccessibleJApplet.
* A new AccessibleJApplet instance is created if necessary.
*
* @return an AccessibleJApplet that serves as the
* AccessibleContext of this JApplet
*/
public AccessibleContext getAccessibleContext() {
if (accessibleContext == null) {
accessibleContext = new AccessibleJApplet();
}
return accessibleContext;
}
/**
* This class implements accessibility support for the
* <code>JApplet class.
*/
protected class AccessibleJApplet extends AccessibleApplet {
// everything moved to new parent, AccessibleApplet
}
}
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