* The {@code Applet} class must be the superclass of any * applet that is to be embedded in a Web page or viewed by the Java * Applet Viewer. The {@code Applet} class provides a standard * interface between applets and their environment. * * @author Arthur van Hoff * @author Chris Warth * @since 1.0 * * @deprecated The Applet API is deprecated, no replacement. */ @Deprecated(since = "9") public class Applet extends Panel { /** * Constructs a new Applet. *
* Note: Many methods in {@code java.applet.Applet} * may be invoked by the applet only after the applet is * fully constructed; applet should avoid calling methods * in {@code java.applet.Applet} in the constructor. * * @exception HeadlessException if GraphicsEnvironment.isHeadless() * returns true. * @see java.awt.GraphicsEnvironment#isHeadless * @since 1.4 */ public Applet() throws HeadlessException { if (GraphicsEnvironment.isHeadless()) { throw new HeadlessException(); } } /** * Applets can be serialized but the following conventions MUST be followed: * * Before Serialization: * An applet must be in STOPPED state. * * After Deserialization: * The applet will be restored in STOPPED state (and most clients will * likely move it into RUNNING state). * The stub field will be restored by the reader. */ private transient AppletStub stub; /* version ID for serialized form. */ private static final long serialVersionUID = -5836846270535785031L; /** * Read an applet from an object input stream. * @param s an object input stream. * @exception HeadlessException if * {@code GraphicsEnvironment.isHeadless()} returns * {@code true} * @serial * @see java.awt.GraphicsEnvironment#isHeadless * @since 1.4 */ private void readObject(ObjectInputStream s) throws ClassNotFoundException, IOException, HeadlessException { if (GraphicsEnvironment.isHeadless()) { throw new HeadlessException(); } s.defaultReadObject(); } /** * Sets this applet's stub. This is done automatically by the system. *
If there is a security manager, its {@code checkPermission} * method is called with the * {@code AWTPermission("setAppletStub")} * permission if a stub has already been set. * @param stub the new stub. * @exception SecurityException if the caller cannot set the stub */ public final void setStub(AppletStub stub) { if (this.stub != null) { SecurityManager s = System.getSecurityManager(); if (s != null) { s.checkPermission(new AWTPermission("setAppletStub")); } } this.stub = stub; } /** * Determines if this applet is active. An applet is marked active * just before its {@code start} method is called. It becomes * inactive just before its {@code stop} method is called. * * @return {@code true} if the applet is active; * {@code false} otherwise. * @see java.applet.Applet#start() * @see java.applet.Applet#stop() */ public boolean isActive() { if (stub != null) { return stub.isActive(); } else { // If stub field not filled in, applet never active return false; } } /** * Gets the URL of the document in which this applet is embedded. * For example, suppose an applet is contained * within the document: *
* http://www.oracle.com/technetwork/java/index.html
*
* http://www.oracle.com/technetwork/java/index.html
*
* <applet code="Clock" width=50 height=50>
* <param name=Color value="blue">
* </applet>
* * then a call to {@code getParameter("Color")} returns the * value {@code "blue"}. *
* The {@code name} argument is case insensitive. * * @param name a parameter name. * @return the value of the named parameter, * or {@code null} if not set. */ public String getParameter(String name) { return stub.getParameter(name); } /** * Determines this applet's context, which allows the applet to * query and affect the environment in which it runs. *
* This environment of an applet represents the document that * contains the applet. * * @return the applet's context. */ public AppletContext getAppletContext() { return stub.getAppletContext(); } /** * Requests that this applet be resized. * * @param width the new requested width for the applet. * @param height the new requested height for the applet. */ @SuppressWarnings("deprecation") public void resize(int width, int height) { Dimension d = size(); if ((d.width != width) || (d.height != height)) { super.resize(width, height); if (stub != null) { stub.appletResize(width, height); } } } /** * Requests that this applet be resized. * * @param d an object giving the new width and height. */ @SuppressWarnings("deprecation") public void resize(Dimension d) { resize(d.width, d.height); } /** * Indicates if this container is a validate root. *
* {@code Applet} objects are the validate roots, and, therefore, they * override this method to return {@code true}. * * @return {@code true} * @since 1.7 * @see java.awt.Container#isValidateRoot */ @Override public boolean isValidateRoot() { return true; } /** * Requests that the argument string be displayed in the * "status window". Many browsers and applet viewers * provide such a window, where the application can inform users of * its current state. * * @param msg a string to display in the status window. */ public void showStatus(String msg) { getAppletContext().showStatus(msg); } /** * Returns an {@code Image} object that can then be painted on * the screen. The {@code url} that is passed as an argument * must specify an absolute URL. *
* This method always returns immediately, whether or not the image * exists. When this applet attempts to draw the image on the screen, * the data will be loaded. The graphics primitives that draw the * image will incrementally paint on the screen. * * @param url an absolute URL giving the location of the image. * @return the image at the specified URL. * @see java.awt.Image */ public Image getImage(URL url) { return getAppletContext().getImage(url); } /** * Returns an {@code Image} object that can then be painted on * the screen. The {@code url} argument must specify an absolute * URL. The {@code name} argument is a specifier that is * relative to the {@code url} argument. *
* This method always returns immediately, whether or not the image * exists. When this applet attempts to draw the image on the screen, * the data will be loaded. The graphics primitives that draw the * image will incrementally paint on the screen. * * @param url an absolute URL giving the base location of the image. * @param name the location of the image, relative to the * {@code url} argument. * @return the image at the specified URL. * @see java.awt.Image */ public Image getImage(URL url, String name) { try { return getImage(new URL(url, name)); } catch (MalformedURLException e) { return null; } } /** * Get an audio clip from the given URL. * * @param url points to the audio clip * @return the audio clip at the specified URL. * * @since 1.2 */ public static final AudioClip newAudioClip(URL url) { return JavaSoundAudioClip.create(url); } /** * Returns the {@code AudioClip} object specified by the * {@code URL} argument. *
* This method always returns immediately, whether or not the audio * clip exists. When this applet attempts to play the audio clip, the * data will be loaded. * * @param url an absolute URL giving the location of the audio clip. * @return the audio clip at the specified URL. * @see java.applet.AudioClip */ public AudioClip getAudioClip(URL url) { return getAppletContext().getAudioClip(url); } /** * Returns the {@code AudioClip} object specified by the * {@code URL} and {@code name} arguments. *
* This method always returns immediately, whether or not the audio * clip exists. When this applet attempts to play the audio clip, the * data will be loaded. * * @param url an absolute URL giving the base location of the * audio clip. * @param name the location of the audio clip, relative to the * {@code url} argument. * @return the audio clip at the specified URL. * @see java.applet.AudioClip */ public AudioClip getAudioClip(URL url, String name) { try { return getAudioClip(new URL(url, name)); } catch (MalformedURLException e) { return null; } } /** * Returns information about this applet. An applet should override * this method to return a {@code String} containing information * about the author, version, and copyright of the applet. *
* The implementation of this method provided by the * {@code Applet} class returns {@code null}. * * @return a string containing information about the author, version, and * copyright of the applet. */ public String getAppletInfo() { return null; } /** * Gets the locale of the applet. It allows the applet * to maintain its own locale separated from the locale * of the browser or appletviewer. * * @return the locale of the applet; if no locale has * been set, the default locale is returned. * @since 1.1 */ public Locale getLocale() { Locale locale = super.getLocale(); if (locale == null) { return Locale.getDefault(); } return locale; } /** * Returns information about the parameters that are understood by * this applet. An applet should override this method to return an * array of {@code Strings} describing these parameters. *
* Each element of the array should be a set of three * {@code Strings} containing the name, the type, and a * description. For example: *
* String pinfo[][] = {
* {"fps", "1-10", "frames per second"},
* {"repeat", "boolean", "repeat image loop"},
* {"imgs", "url", "images directory"}
* };
* * The implementation of this method provided by the * {@code Applet} class returns {@code null}. * * @return an array describing the parameters this applet looks for. */ public String[][] getParameterInfo() { return null; } /** * Plays the audio clip at the specified absolute URL. Nothing * happens if the audio clip cannot be found. * * @param url an absolute URL giving the location of the audio clip. */ public void play(URL url) { AudioClip clip = getAudioClip(url); if (clip != null) { clip.play(); } } /** * Plays the audio clip given the URL and a specifier that is * relative to it. Nothing happens if the audio clip cannot be found. * * @param url an absolute URL giving the base location of the * audio clip. * @param name the location of the audio clip, relative to the * {@code url} argument. */ public void play(URL url, String name) { AudioClip clip = getAudioClip(url, name); if (clip != null) { clip.play(); } } /** * Called by the browser or applet viewer to inform * this applet that it has been loaded into the system. It is always * called before the first time that the {@code start} method is * called. *
* A subclass of {@code Applet} should override this method if * it has initialization to perform. For example, an applet with * threads would use the {@code init} method to create the * threads and the {@code destroy} method to kill them. *
* The implementation of this method provided by the * {@code Applet} class does nothing. * * @see java.applet.Applet#destroy() * @see java.applet.Applet#start() * @see java.applet.Applet#stop() */ public void init() { } /** * Called by the browser or applet viewer to inform * this applet that it should start its execution. It is called after * the {@code init} method and each time the applet is revisited * in a Web page. *
* A subclass of {@code Applet} should override this method if * it has any operation that it wants to perform each time the Web * page containing it is visited. For example, an applet with * animation might want to use the {@code start} method to * resume animation, and the {@code stop} method to suspend the * animation. *
* Note: some methods, such as {@code getLocationOnScreen}, can only * provide meaningful results if the applet is showing. Because * {@code isShowing} returns {@code false} when the applet's * {@code start} is first called, methods requiring * {@code isShowing} to return {@code true} should be called from * a {@code ComponentListener}. *
* The implementation of this method provided by the * {@code Applet} class does nothing. * * @see java.applet.Applet#destroy() * @see java.applet.Applet#init() * @see java.applet.Applet#stop() * @see java.awt.Component#isShowing() * @see java.awt.event.ComponentListener#componentShown(java.awt.event.ComponentEvent) */ public void start() { } /** * Called by the browser or applet viewer to inform * this applet that it should stop its execution. It is called when * the Web page that contains this applet has been replaced by * another page, and also just before the applet is to be destroyed. *
* A subclass of {@code Applet} should override this method if * it has any operation that it wants to perform each time the Web * page containing it is no longer visible. For example, an applet * with animation might want to use the {@code start} method to * resume animation, and the {@code stop} method to suspend the * animation. *
* The implementation of this method provided by the * {@code Applet} class does nothing. * * @see java.applet.Applet#destroy() * @see java.applet.Applet#init() */ public void stop() { } /** * Called by the browser or applet viewer to inform * this applet that it is being reclaimed and that it should destroy * any resources that it has allocated. The {@code stop} method * will always be called before {@code destroy}. *
* A subclass of {@code Applet} should override this method if * it has any operation that it wants to perform before it is * destroyed. For example, an applet with threads would use the * {@code init} method to create the threads and the * {@code destroy} method to kill them. *
* The implementation of this method provided by the * {@code Applet} class does nothing. * * @see java.applet.Applet#init() * @see java.applet.Applet#start() * @see java.applet.Applet#stop() */ public void destroy() { } // // Accessibility support // AccessibleContext accessibleContext = null; /** * Gets the AccessibleContext associated with this Applet. * For applets, the AccessibleContext takes the form of an * AccessibleApplet. * A new AccessibleApplet instance is created if necessary. * * @return an AccessibleApplet that serves as the * AccessibleContext of this Applet * @since 1.3 */ public AccessibleContext getAccessibleContext() { if (accessibleContext == null) { accessibleContext = new AccessibleApplet(); } return accessibleContext; } /** * This class implements accessibility support for the * {@code Applet} class. It provides an implementation of the * Java Accessibility API appropriate to applet user-interface elements. * @since 1.3 */ protected class AccessibleApplet extends AccessibleAWTPanel { private static final long serialVersionUID = 8127374778187708896L; /** * Get the role of this object. * * @return an instance of AccessibleRole describing the role of the * object */ public AccessibleRole getAccessibleRole() { return AccessibleRole.FRAME; } /** * Get the state of this object. * * @return an instance of AccessibleStateSet containing the current * state set of the object * @see AccessibleState */ public AccessibleStateSet getAccessibleStateSet() { AccessibleStateSet states = super.getAccessibleStateSet(); states.add(AccessibleState.ACTIVE); return states; } } }