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/*
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* Copyright 1995-2006 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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package java.applet;
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import java.awt.*;
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import java.awt.image.ColorModel;
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import java.io.IOException;
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import java.io.ObjectInputStream;
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import java.net.URL;
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import java.net.MalformedURLException;
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import java.util.Hashtable;
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import java.util.Locale;
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import javax.accessibility.*;
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/**
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* An applet is a small program that is intended not to be run on
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* its own, but rather to be embedded inside another application.
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* <p>
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* The <code>Applet</code> class must be the superclass of any
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* applet that is to be embedded in a Web page or viewed by the Java
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* Applet Viewer. The <code>Applet</code> class provides a standard
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* interface between applets and their environment.
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*
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* @author Arthur van Hoff
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* @author Chris Warth
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* @since JDK1.0
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*/
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public class Applet extends Panel {
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/**
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* Constructs a new Applet.
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* <p>
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* Note: Many methods in <code>java.applet.Applet</code>
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* may be invoked by the applet only after the applet is
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* fully constructed; applet should avoid calling methods
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* in <code>java.applet.Applet</code> in the constructor.
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*
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* @exception HeadlessException if GraphicsEnvironment.isHeadless()
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* returns true.
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* @see java.awt.GraphicsEnvironment#isHeadless
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* @since 1.4
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*/
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public Applet() throws HeadlessException {
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if (GraphicsEnvironment.isHeadless()) {
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throw new HeadlessException();
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}
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}
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/**
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* Applets can be serialized but the following conventions MUST be followed:
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*
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* Before Serialization:
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* An applet must be in STOPPED state.
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*
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* After Deserialization:
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* The applet will be restored in STOPPED state (and most clients will
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* likely move it into RUNNING state).
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* The stub field will be restored by the reader.
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*/
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transient private AppletStub stub;
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/* version ID for serialized form. */
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private static final long serialVersionUID = -5836846270535785031L;
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/**
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* Read an applet from an object input stream.
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* @exception HeadlessException if
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* <code>GraphicsEnvironment.isHeadless()</code> returns
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* <code>true</code>
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* @serial
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* @see java.awt.GraphicsEnvironment#isHeadless
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* @since 1.4
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*/
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private void readObject(ObjectInputStream s)
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throws ClassNotFoundException, IOException, HeadlessException {
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if (GraphicsEnvironment.isHeadless()) {
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throw new HeadlessException();
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}
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s.defaultReadObject();
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}
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/**
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* Sets this applet's stub. This is done automatically by the system.
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* <p>If there is a security manager, its <code> checkPermission </code>
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* method is called with the
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* <code>AWTPermission("setAppletStub")</code>
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* permission if a stub has already been set.
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* @param stub the new stub.
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* @exception SecurityException if the caller cannot set the stub
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*/
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public final void setStub(AppletStub stub) {
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if (this.stub != null) {
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SecurityManager s = System.getSecurityManager();
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if (s != null) {
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s.checkPermission(new AWTPermission("setAppletStub"));
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}
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}
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this.stub = (AppletStub)stub;
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}
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/**
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* Determines if this applet is active. An applet is marked active
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* just before its <code>start</code> method is called. It becomes
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* inactive just before its <code>stop</code> method is called.
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*
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* @return <code>true</code> if the applet is active;
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* <code>false</code> otherwise.
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* @see java.applet.Applet#start()
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* @see java.applet.Applet#stop()
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*/
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public boolean isActive() {
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if (stub != null) {
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return stub.isActive();
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} else { // If stub field not filled in, applet never active
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return false;
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}
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}
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/**
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* Gets the URL of the document in which this applet is embedded.
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* For example, suppose an applet is contained
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* within the document:
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* <blockquote><pre>
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* http://java.sun.com/products/jdk/1.2/index.html
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* </pre></blockquote>
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* The document base is:
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* <blockquote><pre>
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* http://java.sun.com/products/jdk/1.2/index.html
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* </pre></blockquote>
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*
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* @return the {@link java.net.URL} of the document that contains this
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* applet.
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* @see java.applet.Applet#getCodeBase()
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*/
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public URL getDocumentBase() {
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return stub.getDocumentBase();
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}
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/**
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* Gets the base URL. This is the URL of the directory which contains this applet.
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*
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* @return the base {@link java.net.URL} of
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* the directory which contains this applet.
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* @see java.applet.Applet#getDocumentBase()
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*/
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public URL getCodeBase() {
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return stub.getCodeBase();
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}
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/**
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* Returns the value of the named parameter in the HTML tag. For
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* example, if this applet is specified as
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* <blockquote><pre>
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* <applet code="Clock" width=50 height=50>
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* <param name=Color value="blue">
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* </applet>
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* </pre></blockquote>
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* <p>
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* then a call to <code>getParameter("Color")</code> returns the
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* value <code>"blue"</code>.
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* <p>
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* The <code>name</code> argument is case insensitive.
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*
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* @param name a parameter name.
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* @return the value of the named parameter,
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* or <code>null</code> if not set.
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*/
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public String getParameter(String name) {
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return stub.getParameter(name);
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}
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/**
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* Determines this applet's context, which allows the applet to
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* query and affect the environment in which it runs.
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* <p>
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* This environment of an applet represents the document that
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* contains the applet.
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*
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* @return the applet's context.
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*/
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public AppletContext getAppletContext() {
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return stub.getAppletContext();
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}
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/**
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* Requests that this applet be resized.
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*
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* @param width the new requested width for the applet.
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* @param height the new requested height for the applet.
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*/
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public void resize(int width, int height) {
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Dimension d = size();
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if ((d.width != width) || (d.height != height)) {
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super.resize(width, height);
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if (stub != null) {
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stub.appletResize(width, height);
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}
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}
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}
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/**
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* Requests that this applet be resized.
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*
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* @param d an object giving the new width and height.
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*/
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public void resize(Dimension d) {
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resize(d.width, d.height);
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}
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/**
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* Requests that the argument string be displayed in the
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* "status window". Many browsers and applet viewers
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* provide such a window, where the application can inform users of
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* its current state.
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*
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* @param msg a string to display in the status window.
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*/
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public void showStatus(String msg) {
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getAppletContext().showStatus(msg);
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}
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/**
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* Returns an <code>Image</code> object that can then be painted on
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* the screen. The <code>url</code> that is passed as an argument
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* must specify an absolute URL.
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* <p>
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* This method always returns immediately, whether or not the image
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* exists. When this applet attempts to draw the image on the screen,
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* the data will be loaded. The graphics primitives that draw the
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* image will incrementally paint on the screen.
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*
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* @param url an absolute URL giving the location of the image.
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* @return the image at the specified URL.
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* @see java.awt.Image
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*/
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public Image getImage(URL url) {
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return getAppletContext().getImage(url);
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}
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/**
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* Returns an <code>Image</code> object that can then be painted on
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* the screen. The <code>url</code> argument must specify an absolute
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* URL. The <code>name</code> argument is a specifier that is
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* relative to the <code>url</code> argument.
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* <p>
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* This method always returns immediately, whether or not the image
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* exists. When this applet attempts to draw the image on the screen,
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* the data will be loaded. The graphics primitives that draw the
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* image will incrementally paint on the screen.
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*
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* @param url an absolute URL giving the base location of the image.
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* @param name the location of the image, relative to the
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* <code>url</code> argument.
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* @return the image at the specified URL.
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* @see java.awt.Image
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*/
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public Image getImage(URL url, String name) {
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try {
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return getImage(new URL(url, name));
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} catch (MalformedURLException e) {
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return null;
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}
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}
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/**
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* Get an audio clip from the given URL.
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*
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* @param url points to the audio clip
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* @return the audio clip at the specified URL.
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*
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* @since 1.2
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*/
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public final static AudioClip newAudioClip(URL url) {
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return new sun.applet.AppletAudioClip(url);
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}
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/**
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* Returns the <code>AudioClip</code> object specified by the
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* <code>URL</code> argument.
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* <p>
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* This method always returns immediately, whether or not the audio
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* clip exists. When this applet attempts to play the audio clip, the
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* data will be loaded.
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*
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* @param url an absolute URL giving the location of the audio clip.
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* @return the audio clip at the specified URL.
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* @see java.applet.AudioClip
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*/
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public AudioClip getAudioClip(URL url) {
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return getAppletContext().getAudioClip(url);
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}
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/**
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* Returns the <code>AudioClip</code> object specified by the
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* <code>URL</code> and <code>name</code> arguments.
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* <p>
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* This method always returns immediately, whether or not the audio
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* clip exists. When this applet attempts to play the audio clip, the
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* data will be loaded.
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*
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* @param url an absolute URL giving the base location of the
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* audio clip.
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* @param name the location of the audio clip, relative to the
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* <code>url</code> argument.
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* @return the audio clip at the specified URL.
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* @see java.applet.AudioClip
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*/
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public AudioClip getAudioClip(URL url, String name) {
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try {
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return getAudioClip(new URL(url, name));
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} catch (MalformedURLException e) {
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return null;
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}
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}
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/**
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* Returns information about this applet. An applet should override
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* this method to return a <code>String</code> containing information
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* about the author, version, and copyright of the applet.
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* <p>
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* The implementation of this method provided by the
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* <code>Applet</code> class returns <code>null</code>.
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*
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* @return a string containing information about the author, version, and
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* copyright of the applet.
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*/
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public String getAppletInfo() {
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return null;
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}
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/**
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* Gets the locale of the applet. It allows the applet
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* to maintain its own locale separated from the locale
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* of the browser or appletviewer.
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*
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* @return the locale of the applet; if no locale has
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* been set, the default locale is returned.
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* @since JDK1.1
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*/
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362 |
public Locale getLocale() {
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363 |
Locale locale = super.getLocale();
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364 |
if (locale == null) {
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return Locale.getDefault();
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366 |
}
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return locale;
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}
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369 |
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370 |
/**
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371 |
* Returns information about the parameters that are understood by
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372 |
* this applet. An applet should override this method to return an
|
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373 |
* array of <code>Strings</code> describing these parameters.
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374 |
* <p>
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375 |
* Each element of the array should be a set of three
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376 |
* <code>Strings</code> containing the name, the type, and a
|
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377 |
* description. For example:
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378 |
* <p><blockquote><pre>
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379 |
* String pinfo[][] = {
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380 |
* {"fps", "1-10", "frames per second"},
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381 |
* {"repeat", "boolean", "repeat image loop"},
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382 |
* {"imgs", "url", "images directory"}
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383 |
* };
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384 |
* </pre></blockquote>
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385 |
* <p>
|
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386 |
* The implementation of this method provided by the
|
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387 |
* <code>Applet</code> class returns <code>null</code>.
|
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388 |
*
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389 |
* @return an array describing the parameters this applet looks for.
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*/
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391 |
public String[][] getParameterInfo() {
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392 |
return null;
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393 |
}
|
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394 |
|
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395 |
/**
|
|
396 |
* Plays the audio clip at the specified absolute URL. Nothing
|
|
397 |
* happens if the audio clip cannot be found.
|
|
398 |
*
|
|
399 |
* @param url an absolute URL giving the location of the audio clip.
|
|
400 |
*/
|
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401 |
public void play(URL url) {
|
|
402 |
AudioClip clip = getAudioClip(url);
|
|
403 |
if (clip != null) {
|
|
404 |
clip.play();
|
|
405 |
}
|
|
406 |
}
|
|
407 |
|
|
408 |
/**
|
|
409 |
* Plays the audio clip given the URL and a specifier that is
|
|
410 |
* relative to it. Nothing happens if the audio clip cannot be found.
|
|
411 |
*
|
|
412 |
* @param url an absolute URL giving the base location of the
|
|
413 |
* audio clip.
|
|
414 |
* @param name the location of the audio clip, relative to the
|
|
415 |
* <code>url</code> argument.
|
|
416 |
*/
|
|
417 |
public void play(URL url, String name) {
|
|
418 |
AudioClip clip = getAudioClip(url, name);
|
|
419 |
if (clip != null) {
|
|
420 |
clip.play();
|
|
421 |
}
|
|
422 |
}
|
|
423 |
|
|
424 |
/**
|
|
425 |
* Called by the browser or applet viewer to inform
|
|
426 |
* this applet that it has been loaded into the system. It is always
|
|
427 |
* called before the first time that the <code>start</code> method is
|
|
428 |
* called.
|
|
429 |
* <p>
|
|
430 |
* A subclass of <code>Applet</code> should override this method if
|
|
431 |
* it has initialization to perform. For example, an applet with
|
|
432 |
* threads would use the <code>init</code> method to create the
|
|
433 |
* threads and the <code>destroy</code> method to kill them.
|
|
434 |
* <p>
|
|
435 |
* The implementation of this method provided by the
|
|
436 |
* <code>Applet</code> class does nothing.
|
|
437 |
*
|
|
438 |
* @see java.applet.Applet#destroy()
|
|
439 |
* @see java.applet.Applet#start()
|
|
440 |
* @see java.applet.Applet#stop()
|
|
441 |
*/
|
|
442 |
public void init() {
|
|
443 |
}
|
|
444 |
|
|
445 |
/**
|
|
446 |
* Called by the browser or applet viewer to inform
|
|
447 |
* this applet that it should start its execution. It is called after
|
|
448 |
* the <code>init</code> method and each time the applet is revisited
|
|
449 |
* in a Web page.
|
|
450 |
* <p>
|
|
451 |
* A subclass of <code>Applet</code> should override this method if
|
|
452 |
* it has any operation that it wants to perform each time the Web
|
|
453 |
* page containing it is visited. For example, an applet with
|
|
454 |
* animation might want to use the <code>start</code> method to
|
|
455 |
* resume animation, and the <code>stop</code> method to suspend the
|
|
456 |
* animation.
|
|
457 |
* <p>
|
|
458 |
* Note: some methods, such as <code>getLocationOnScreen</code>, can only
|
|
459 |
* provide meaningful results if the applet is showing. Because
|
|
460 |
* <code>isShowing</code> returns <code>false</code> when the applet's
|
|
461 |
* <code>start</code> is first called, methods requiring
|
|
462 |
* <code>isShowing</code> to return <code>true</code> should be called from
|
|
463 |
* a <code>ComponentListener</code>.
|
|
464 |
* <p>
|
|
465 |
* The implementation of this method provided by the
|
|
466 |
* <code>Applet</code> class does nothing.
|
|
467 |
*
|
|
468 |
* @see java.applet.Applet#destroy()
|
|
469 |
* @see java.applet.Applet#init()
|
|
470 |
* @see java.applet.Applet#stop()
|
|
471 |
* @see java.awt.Component#isShowing()
|
|
472 |
* @see java.awt.event.ComponentListener#componentShown(java.awt.event.ComponentEvent)
|
|
473 |
*/
|
|
474 |
public void start() {
|
|
475 |
}
|
|
476 |
|
|
477 |
/**
|
|
478 |
* Called by the browser or applet viewer to inform
|
|
479 |
* this applet that it should stop its execution. It is called when
|
|
480 |
* the Web page that contains this applet has been replaced by
|
|
481 |
* another page, and also just before the applet is to be destroyed.
|
|
482 |
* <p>
|
|
483 |
* A subclass of <code>Applet</code> should override this method if
|
|
484 |
* it has any operation that it wants to perform each time the Web
|
|
485 |
* page containing it is no longer visible. For example, an applet
|
|
486 |
* with animation might want to use the <code>start</code> method to
|
|
487 |
* resume animation, and the <code>stop</code> method to suspend the
|
|
488 |
* animation.
|
|
489 |
* <p>
|
|
490 |
* The implementation of this method provided by the
|
|
491 |
* <code>Applet</code> class does nothing.
|
|
492 |
*
|
|
493 |
* @see java.applet.Applet#destroy()
|
|
494 |
* @see java.applet.Applet#init()
|
|
495 |
*/
|
|
496 |
public void stop() {
|
|
497 |
}
|
|
498 |
|
|
499 |
/**
|
|
500 |
* Called by the browser or applet viewer to inform
|
|
501 |
* this applet that it is being reclaimed and that it should destroy
|
|
502 |
* any resources that it has allocated. The <code>stop</code> method
|
|
503 |
* will always be called before <code>destroy</code>.
|
|
504 |
* <p>
|
|
505 |
* A subclass of <code>Applet</code> should override this method if
|
|
506 |
* it has any operation that it wants to perform before it is
|
|
507 |
* destroyed. For example, an applet with threads would use the
|
|
508 |
* <code>init</code> method to create the threads and the
|
|
509 |
* <code>destroy</code> method to kill them.
|
|
510 |
* <p>
|
|
511 |
* The implementation of this method provided by the
|
|
512 |
* <code>Applet</code> class does nothing.
|
|
513 |
*
|
|
514 |
* @see java.applet.Applet#init()
|
|
515 |
* @see java.applet.Applet#start()
|
|
516 |
* @see java.applet.Applet#stop()
|
|
517 |
*/
|
|
518 |
public void destroy() {
|
|
519 |
}
|
|
520 |
|
|
521 |
//
|
|
522 |
// Accessibility support
|
|
523 |
//
|
|
524 |
|
|
525 |
AccessibleContext accessibleContext = null;
|
|
526 |
|
|
527 |
/**
|
|
528 |
* Gets the AccessibleContext associated with this Applet.
|
|
529 |
* For applets, the AccessibleContext takes the form of an
|
|
530 |
* AccessibleApplet.
|
|
531 |
* A new AccessibleApplet instance is created if necessary.
|
|
532 |
*
|
|
533 |
* @return an AccessibleApplet that serves as the
|
|
534 |
* AccessibleContext of this Applet
|
|
535 |
* @since 1.3
|
|
536 |
*/
|
|
537 |
public AccessibleContext getAccessibleContext() {
|
|
538 |
if (accessibleContext == null) {
|
|
539 |
accessibleContext = new AccessibleApplet();
|
|
540 |
}
|
|
541 |
return accessibleContext;
|
|
542 |
}
|
|
543 |
|
|
544 |
/**
|
|
545 |
* This class implements accessibility support for the
|
|
546 |
* <code>Applet</code> class. It provides an implementation of the
|
|
547 |
* Java Accessibility API appropriate to applet user-interface elements.
|
|
548 |
* @since 1.3
|
|
549 |
*/
|
|
550 |
protected class AccessibleApplet extends AccessibleAWTPanel {
|
|
551 |
|
|
552 |
private static final long serialVersionUID = 8127374778187708896L;
|
|
553 |
|
|
554 |
/**
|
|
555 |
* Get the role of this object.
|
|
556 |
*
|
|
557 |
* @return an instance of AccessibleRole describing the role of the
|
|
558 |
* object
|
|
559 |
*/
|
|
560 |
public AccessibleRole getAccessibleRole() {
|
|
561 |
return AccessibleRole.FRAME;
|
|
562 |
}
|
|
563 |
|
|
564 |
/**
|
|
565 |
* Get the state of this object.
|
|
566 |
*
|
|
567 |
* @return an instance of AccessibleStateSet containing the current
|
|
568 |
* state set of the object
|
|
569 |
* @see AccessibleState
|
|
570 |
*/
|
|
571 |
public AccessibleStateSet getAccessibleStateSet() {
|
|
572 |
AccessibleStateSet states = super.getAccessibleStateSet();
|
|
573 |
states.add(AccessibleState.ACTIVE);
|
|
574 |
return states;
|
|
575 |
}
|
|
576 |
|
|
577 |
}
|
|
578 |
}
|