1 /*

     2  * Copyright (c) 1995, 2014, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package sun.applet;

    27 

    28 import java.awt.Toolkit;

    29 import java.awt.Image;

    30 import java.lang.ref.SoftReference;

    31 import sun.awt.image.URLImageSource;

    32 import java.net.URL;

    33 

    34 @Deprecated(since = "9")

    35 class AppletImageRef {

    36     private SoftReference<Image> soft = null;

    37 

    38     URL url;

    39 

    40     /**

    41      * Returns a pointer to the object referenced by this Ref.  If the object

    42      * has been thrown away by the garbage collector, it will be

    43      * reconstituted. This method does everything necessary to ensure that the garbage

    44      * collector throws things away in Least Recently Used(LRU) order.  Applications should

    45      * never override this method. The get() method effectively caches calls to

    46      * reconstitute().

    47      */

    48     public synchronized Image get() {

    49         Image t = check();

    50         if (t == null) {

    51             t = reconstitute();

    52             setThing(t);

    53         }

    54         return t;

    55     }

    56 

    57     /**

    58      * Create the Ref

    59      */

    60     AppletImageRef(URL url) {

    61         this.url = url;

    62     }

    63 

    64     /**

    65      * Flushes the cached object.  Forces the next invocation of get() to

    66      * invoke reconstitute().

    67      */

    68     public synchronized void flush() {

    69         SoftReference<Image> s = soft;

    70         if (s != null) s.clear();

    71         soft = null;

    72     }

    73 

    74     /**

    75      * Sets the thing to the specified object.

    76      * @param thing the specified object

    77      */

    78     public synchronized void setThing(Image thing) {

    79         flush();

    80         soft = new SoftReference<>(thing);

    81     }

    82 

    83     /**

    84      * Checks to see what object is being pointed at by this Ref and returns it.

    85      */

    86     public synchronized Image check() {

    87         SoftReference<Image> s = soft;

    88         if (s == null) return null;

    89         return s.get();

    90     }

    91 

    92     /**

    93      * Reconsitute the image.  Only called when the ref has been flushed.

    94      */

    95     public Image reconstitute() {

    96         Image img = Toolkit.getDefaultToolkit().createImage(new URLImageSource(url));

    97         return img;

    98     }

    99 }