Java tutorial
/* * Copyright (c) 1997, 2018, 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.applet.Applet; import java.awt.AWTEvent; import java.awt.BorderLayout; import java.awt.Color; import java.awt.Component; import java.awt.Container; import java.awt.Graphics; import java.awt.HeadlessException; import java.awt.LayoutManager; import java.beans.BeanProperty; import java.beans.JavaBean; import javax.accessibility.Accessible; import javax.accessibility.AccessibleContext; /** * An extended version of <code>java.applet.Applet</code> that adds support for * the JFC/Swing component architecture. * You can find task-oriented documentation about using <code>JApplet</code> * in <em>The Java Tutorial</em>, * in the section * <a href="https://docs.oracle.com/javase/tutorial/uiswing/components/applet.html">How to Make Applets</a>. * <p> * The <code>JApplet</code> class is slightly incompatible with * <code>java.applet.Applet</code>. <code>JApplet</code> contains a * <code>JRootPane</code> as its only child. The <code>contentPane</code> * should be the parent of any children of the <code>JApplet</code>. * 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</code>. * The <code>contentPane</code> will always be non-<code>null</code>. * Attempting to set it to <code>null</code> will cause the * <code>JApplet</code> to throw an exception. The default * <code>contentPane</code> will have a <code>BorderLayout</code> * manager set on it. * Refer to {@link javax.swing.RootPaneContainer} * for details on adding, removing and setting the <code>LayoutManager</code> * of a <code>JApplet</code>. * <p> * Please see the <code>JRootPane</code> documentation for a * complete description of the <code>contentPane</code>, <code>glassPane</code>, * and <code>layeredPane</code> properties. * <p> * <strong>Warning:</strong> Swing is not thread safe. For more * information see <a * href="package-summary.html#threading">Swing's Threading * Policy</a>. * <p> * <strong>Warning:</strong> * 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</code> package. * Please see {@link java.beans.XMLEncoder}. * * @see javax.swing.RootPaneContainer * * @author Arnaud Weber * @since 1.2 * * @deprecated The Applet API is deprecated, no replacement. */ @Deprecated(since = "9") @JavaBean(defaultProperty = "JMenuBar", description = "Swing's Applet subclass.") @SwingContainer(delegate = "getContentPane") @SuppressWarnings("serial") // Same-version serialization only public class JApplet extends Applet implements Accessible, RootPaneContainer, TransferHandler.HasGetTransferHandler { /** * @see #getRootPane * @see #setRootPane */ protected JRootPane rootPane; /** * If true then calls to <code>add</code> and <code>setLayout</code> * will be forwarded to the <code>contentPane</code>. This is initially * false, but is set to true when the <code>JApplet</code> is constructed. * * @see #isRootPaneCheckingEnabled * @see #setRootPaneCheckingEnabled * @see javax.swing.RootPaneContainer */ protected boolean rootPaneCheckingEnabled = false; /** * The <code>TransferHandler</code> 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</code>. * * @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. * * @return a new {@code JRootPane} */ 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="https://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</em>, for more information. * * @param newHandler the new {@code TransferHandler} * * @see TransferHandler * @see #getTransferHandler * @see java.awt.Component#setDropTarget * @since 1.6 */ @BeanProperty(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</code> property. * * @return the value of the <code>transferHandler</code> property * * @see TransferHandler * @see #setTransferHandler * @since 1.6 */ public TransferHandler getTransferHandler() { return transferHandler; } /** * Just calls <code>paint(g)</code>. 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 */ @BeanProperty(bound = false, hidden = true, description = "The menubar for accessing pulldown menus from this applet.") public void setJMenuBar(final JMenuBar menuBar) { getRootPane().setJMenuBar(menuBar); } /** * Returns the menubar set on this applet. * * @return the menubar set on this applet * @see #setJMenuBar */ public JMenuBar getJMenuBar() { return getRootPane().getJMenuBar(); } /** * Returns whether calls to <code>add</code> and * <code>setLayout</code> are forwarded to the <code>contentPane</code>. * * @return true if <code>add</code> and <code>setLayout</code> * 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</code> and * <code>setLayout</code> are forwarded to the <code>contentPane</code>. * * @param enabled true if <code>add</code> and <code>setLayout</code> * are forwarded, false if they should operate directly on the * <code>JApplet</code>. * * @see #addImpl * @see #setLayout * @see #isRootPaneCheckingEnabled * @see javax.swing.RootPaneContainer */ @BeanProperty(hidden = true, description = "Whether the add and setLayout methods are forwarded") protected void setRootPaneCheckingEnabled(boolean enabled) { rootPaneCheckingEnabled = enabled; } /** * Adds the specified child <code>Component</code>. * This method is overridden to conditionally forward calls to the * <code>contentPane</code>. * By default, children are added to the <code>contentPane</code> 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</code> 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</code> is not the <code>rootPane</code>, this will forward * the call to the <code>contentPane</code>. This will do nothing if * <code>comp</code> is not a child of the <code>JFrame</code> or * <code>contentPane</code>. * * @param comp the component to be removed * @throws NullPointerException if <code>comp</code> 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</code>. * Overridden to conditionally forward the call to the * <code>contentPane</code>. * Refer to {@link javax.swing.RootPaneContainer} for * more information. * * @param manager the <code>LayoutManager</code> * @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 */ @BeanProperty(bound = false, hidden = true, description = "the RootPane object for this applet.") 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 */ 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 */ @BeanProperty(bound = false, 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 */ @BeanProperty(bound = false, 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 */ @BeanProperty(bound = false, hidden = true, description = "A transparent pane used for menu rendering.") public void setGlassPane(Component glassPane) { getRootPane().setGlassPane(glassPane); } /** * {@inheritDoc} * * @since 1.6 */ @BeanProperty(bound = false) public Graphics getGraphics() { JComponent.getGraphicsInvoked(this); return super.getGraphics(); } /** * Repaints the specified rectangle of this component within * <code>time</code> milliseconds. Refer to <code>RepaintManager</code> * for details on how the repaint is handled. * * @param time maximum time in milliseconds before update * @param x the <i>x</i> coordinate * @param y the <i>y</i> 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</code>. * * @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 //////////////// /** * {@code AccessibleContext} associated with this {@code JApplet} */ 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</code> class. */ protected class AccessibleJApplet extends AccessibleApplet { // everything moved to new parent, AccessibleApplet } }