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| 1 | /* | ||
| 2 | * Copyright (c) 1995, 2006, 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 java.net; | ||
| 27 | |||
| 28 | import java.io.IOException; | ||
| 29 | |||
| 30 | /** | ||
| 31 | * The abstract class <code>ContentHandler</code> is the superclass | ||
| 32 | * of all classes that read an <code>Object</code> from a | ||
| 33 | * <code>URLConnection</code>. | ||
| 34 | * <p> | ||
| 35 | * An application does not generally call the | ||
| 36 | * <code>getContent</code> method in this class directly. Instead, an | ||
| 37 | * application calls the <code>getContent</code> method in class | ||
| 38 | * <code>URL</code> or in <code>URLConnection</code>. | ||
| 39 | * The application's content handler factory (an instance of a class that | ||
| 40 | * implements the interface <code>ContentHandlerFactory</code> set | ||
| 41 | * up by a call to <code>setContentHandler</code>) is | ||
| 42 | * called with a <code>String</code> giving the MIME type of the | ||
| 43 | * object being received on the socket. The factory returns an | ||
| 44 | * instance of a subclass of <code>ContentHandler</code>, and its | ||
| 45 | * <code>getContent</code> method is called to create the object. | ||
| 46 | * <p> | ||
| 47 | * If no content handler could be found, URLConnection will | ||
| 48 | * look for a content handler in a user-defineable set of places. | ||
| 49 | * By default it looks in sun.net.www.content, but users can define a | ||
| 50 | * vertical-bar delimited set of class prefixes to search through in | ||
| 51 | * addition by defining the java.content.handler.pkgs property. | ||
| 52 | * The class name must be of the form: | ||
| 53 | * <pre> | ||
| 54 | * {package-prefix}.{major}.{minor} | ||
| 55 | * e.g. | ||
| 56 | * YoyoDyne.experimental.text.plain | ||
| 57 | * </pre> | ||
| 58 | * If the loading of the content handler class would be performed by | ||
| 59 | * a classloader that is outside of the delegation chain of the caller, | ||
| 60 | * the JVM will need the RuntimePermission "getClassLoader". | ||
| 61 | * | ||
| 62 | * @author James Gosling | ||
| 63 | * @see java.net.ContentHandler#getContent(java.net.URLConnection) | ||
| 64 | * @see java.net.ContentHandlerFactory | ||
| 65 | * @see java.net.URL#getContent() | ||
| 66 | * @see java.net.URLConnection | ||
| 67 | * @see java.net.URLConnection#getContent() | ||
| 68 | * @see java.net.URLConnection#setContentHandlerFactory(java.net.ContentHandlerFactory) | ||
| 69 | * @since JDK1.0 | ||
| 70 | */ | ||
| 71 | abstract public class ContentHandler { | ||
| 72 | /** | ||
| 73 | * Given a URL connect stream positioned at the beginning of the | ||
| 74 | * representation of an object, this method reads that stream and | ||
| 75 | * creates an object from it. | ||
| 76 | * | ||
| 77 | * @param urlc a URL connection. | ||
| 78 | * @return the object read by the <code>ContentHandler</code>. | ||
| 79 | * @exception IOException if an I/O error occurs while reading the object. | ||
| 80 | */ | ||
| 81 | abstract public Object getContent(URLConnection urlc) throws IOException; | ||
| 82 | |||
| 83 | /** | ||
| 84 | * Given a URL connect stream positioned at the beginning of the | ||
| 85 | * representation of an object, this method reads that stream and | ||
| 86 | * creates an object that matches one of the types specified. | ||
| 87 | * | ||
| 88 | * The default implementation of this method should call getContent() | ||
| 89 | * and screen the return type for a match of the suggested types. | ||
| 90 | * | ||
| 91 | * @param urlc a URL connection. | ||
| 92 | * @param classes an array of types requested | ||
| 93 | * @return the object read by the <code>ContentHandler</code> that is | ||
| 94 | * the first match of the suggested types. | ||
| 95 | * null if none of the requested are supported. | ||
| 96 | * @exception IOException if an I/O error occurs while reading the object. | ||
| 97 | * @since 1.3 | ||
| 98 | */ | ||
| 99 | public Object getContent(URLConnection urlc, Class[] classes) throws IOException { | ||
| 100 | Object obj = getContent(urlc); | ||
| 101 | |||
| 102 | for (int i = 0; i < classes.length; i++) { | ||
| 103 | if (classes[i].isInstance(obj)) { | ||
| 104 | return obj; | ||
| 105 | } | ||
| 106 | } | ||
| 107 | return null; | ||
| 108 | } | ||
| 109 | |||
| 110 | } | ||