/*
* Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*/
package java.applet;
import java.awt.*;
import java.awt.image.
ColorModel;
import java.io.
IOException;
import java.io.
ObjectInputStream;
import java.net.
URL;
import java.net.
MalformedURLException;
import java.util.
Hashtable;
import java.util.
Locale;
import javax.accessibility.*;
/**
* An applet is a small program that is intended not to be run on
* its own, but rather to be embedded inside another application.
* <p>
* The <code>Applet</code> 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</code> class provides a standard
* interface between applets and their environment.
*
* @author Arthur van Hoff
* @author Chris Warth
* @since JDK1.0
*/
public class
Applet extends
Panel {
/**
* Constructs a new Applet.
* <p>
* Note: Many methods in <code>java.applet.Applet</code>
* may be invoked by the applet only after the applet is
* fully constructed; applet should avoid calling methods
* in <code>java.applet.Applet</code> 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.
*/
transient private
AppletStub stub;
/* version ID for serialized form. */
private static final long
serialVersionUID = -5836846270535785031L;
/**
* Read an applet from an object input stream.
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless()</code> returns
* <code>true</code>
* @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.
* <p>If there is a security manager, its <code> checkPermission </code>
* method is called with the
* <code>AWTPermission("setAppletStub")</code>
* 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</code> method is called. It becomes
* inactive just before its <code>stop</code> method is called.
*
* @return <code>true</code> if the applet is active;
* <code>false</code> 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:
* <blockquote><pre>
* http://www.oracle.com/technetwork/java/index.html
* </pre></blockquote>
* The document base is:
* <blockquote><pre>
* http://www.oracle.com/technetwork/java/index.html
* </pre></blockquote>
*
* @return the {@link java.net.URL} of the document that contains this
* applet.
* @see java.applet.Applet#getCodeBase()
*/
public
URL getDocumentBase() {
return
stub.
getDocumentBase();
}
/**
* Gets the base URL. This is the URL of the directory which contains this applet.
*
* @return the base {@link java.net.URL} of
* the directory which contains this applet.
* @see java.applet.Applet#getDocumentBase()
*/
public
URL getCodeBase() {
return
stub.
getCodeBase();
}
/**
* Returns the value of the named parameter in the HTML tag. For
* example, if this applet is specified as
* <blockquote><pre>
* <applet code="Clock" width=50 height=50>
* <param name=Color value="blue">
* </applet>
* </pre></blockquote>
* <p>
* then a call to <code>getParameter("Color")</code> returns the
* value <code>"blue"</code>.
* <p>
* The <code>name</code> argument is case insensitive.
*
* @param name a parameter name.
* @return the value of the named parameter,
* or <code>null</code> 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.
* <p>
* 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.
* <p>
* {@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</code> object that can then be painted on
* the screen. The <code>url</code> that is passed as an argument
* must specify an absolute URL.
* <p>
* 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</code> object that can then be painted on
* the screen. The <code>url</code> argument must specify an absolute
* URL. The <code>name</code> argument is a specifier that is
* relative to the <code>url</code> argument.
* <p>
* 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</code> 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 final static
AudioClip newAudioClip(
URL url) {
return new sun.applet.
AppletAudioClip(
url);
}
/**
* Returns the <code>AudioClip</code> object specified by the
* <code>URL</code> argument.
* <p>
* 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</code> object specified by the
* <code>URL</code> and <code>name</code> arguments.
* <p>
* 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</code> 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</code> containing information
* about the author, version, and copyright of the applet.
* <p>
* The implementation of this method provided by the
* <code>Applet</code> class returns <code>null</code>.
*
* @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 JDK1.1
*/
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</code> describing these parameters.
* <p>
* Each element of the array should be a set of three
* <code>Strings</code> containing the name, the type, and a
* description. For example:
* <blockquote><pre>
* String pinfo[][] = {
* {"fps", "1-10", "frames per second"},
* {"repeat", "boolean", "repeat image loop"},
* {"imgs", "url", "images directory"}
* };
* </pre></blockquote>
* <p>
* The implementation of this method provided by the
* <code>Applet</code> class returns <code>null</code>.
*
* @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</code> 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</code> method is
* called.
* <p>
* A subclass of <code>Applet</code> should override this method if
* it has initialization to perform. For example, an applet with
* threads would use the <code>init</code> method to create the
* threads and the <code>destroy</code> method to kill them.
* <p>
* The implementation of this method provided by the
* <code>Applet</code> 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</code> method and each time the applet is revisited
* in a Web page.
* <p>
* A subclass of <code>Applet</code> 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</code> method to
* resume animation, and the <code>stop</code> method to suspend the
* animation.
* <p>
* Note: some methods, such as <code>getLocationOnScreen</code>, can only
* provide meaningful results if the applet is showing. Because
* <code>isShowing</code> returns <code>false</code> when the applet's
* <code>start</code> is first called, methods requiring
* <code>isShowing</code> to return <code>true</code> should be called from
* a <code>ComponentListener</code>.
* <p>
* The implementation of this method provided by the
* <code>Applet</code> 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.
* <p>
* A subclass of <code>Applet</code> 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</code> method to
* resume animation, and the <code>stop</code> method to suspend the
* animation.
* <p>
* The implementation of this method provided by the
* <code>Applet</code> 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</code> method
* will always be called before <code>destroy</code>.
* <p>
* A subclass of <code>Applet</code> 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</code> method to create the threads and the
* <code>destroy</code> method to kill them.
* <p>
* The implementation of this method provided by the
* <code>Applet</code> 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</code> 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;
}
}
}