appletcontext.java

《移动Agent技术》一书的所有章节源代码。

/*
 * @(#)AppletContext.java	1.14 96/11/23
 * 
 * Copyright (c) 1995, 1996 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the confidential and proprietary information of Sun
 * Microsystems, Inc. ("Confidential Information").  You shall not
 * disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into
 * with Sun.
 * 
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
 * SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES
 * SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING
 * THIS SOFTWARE OR ITS DERIVATIVES.
 * 
 * CopyrightVersion 1.1_beta
 * 
 */

package java.applet;

import java.awt.Image;
import java.awt.Graphics;
import java.awt.image.ColorModel;
import java.net.URL;
import java.util.Enumeration;

/**
 * This interface corresponds to an applet's environment: the 
 * document containing the applet and the other applets in the same 
 * document. 
 * <p>
 * The methods in this interface can be used by an applet to obtain 
 * information about its environment. 
 *
 * @author 	Arthur van Hoff
 * @version     1.22, 01/09/98
 * @since       JDK1.0
 */
public interface AppletContext {
    /**
     * Creates an audio clip. 
     *
     * @param   url   an absolute URL giving the location of the audio clip.
     * @return  the audio clip at the specified URL.
     * @since   JDK1.0
     */
    AudioClip getAudioClip(URL url);

    /**
     * Returns an <code>Image</code> object that can then be painted on 
     * the screen. The <code>url</code> argument<code> </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 the 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
     * @since   JDK1.0
     */
    Image getImage(URL url);

    /**
     * Finds and returns the applet in the document represented by this 
     * applet context with the given name. The name can be set in the 
     * HTML tag by setting the <code>name</code> attribute. 
     *
     * @param   name   an applet name.
     * @return  the applet with the given name, or <code>null</code> if
     *          not found.
     * @since   JDK1.0
     */
    Applet getApplet(String name);

    /**
     * Finds all the applets in the document represented by this applet 
     * context. 
     *
     * @return  an enumeration of all applets in the document represented by
     *          this applet context.
     * @since   JDK1.0
     */
    Enumeration getApplets();

    /**
     * Replaces the Web page currently being viewed with the given URL. 
     * This method may be ignored by applet contexts that are not 
     * browsers. 
     *
     * @param   url   an absolute URL giving the location of the document.
     * @since   JDK1.0
     */
    void showDocument(URL url);

    /**
     * Requests that the browser or applet viewer show the Web page 
     * indicated by the <code>url</code> argument. The 
     * <code>target</code> argument indicates in which HTML frame the 
     * document is to be displayed. 
     * The target argument is interpreted as follows:
     * <p>
     * <center><table border="3"> 
     * <tr><td><code>"_self"</code>  <td>Show in the window and frame that 
     *                                   contain the applet.</tr>
     * <tr><td><code>"_parent"</code><td>Show in the applet's parent frame. If 
     *                                   the applet's frame has no parent frame, 
     *                                   acts the same as "_self".</tr>
     * <tr><td><code>"_top"</code>   <td>Show in the top-level frame of the applet's 
     *                                   window. If the applet's frame is the 
     *                                   top-level frame, acts the same as "_self".</tr>
     * <tr><td><code>"_blank"</code> <td>Show in a new, unnamed
     *                                   top-level window.</tr>
     * <tr><td><i>name</i><td>Show in the frame or window named <i>name</i>. If 
     *                        a target named <i>name</i> does not already exist, a 
     *                        new top-level window with the specified name is created, 
     *                        and the document is shown there.</tr>
     * </table> </center>
     * <p>
     * An applet viewer or browser is free to ignore <code>showDocument</code>. 
     *
     * @param   url   an absolute URL giving the location of the document.
     * @param   target   a <code>String</code> indicating where to display
     *                   the page.
     * @since   JDK1.0
     */
    public void showDocument(URL url, String target);

    /**
     * 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   status   a string to display in the status window.
     * @since   JDK1.0
     */
    void showStatus(String status);
}