/* * Copyright (c) 1995, 2006, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.net; import java.io.IOException; /** * The abstract class ContentHandler is the superclass * of all classes that read an Object from a * URLConnection. *

* An application does not generally call the * getContent method in this class directly. Instead, an * application calls the getContent method in class * URL or in URLConnection. * The application's content handler factory (an instance of a class that * implements the interface ContentHandlerFactory set * up by a call to setContentHandler) is * called with a String giving the MIME type of the * object being received on the socket. The factory returns an * instance of a subclass of ContentHandler, and its * getContent method is called to create the object. *

* If no content handler could be found, URLConnection will * look for a content handler in a user-defineable set of places. * By default it looks in sun.net.www.content, but users can define a * vertical-bar delimited set of class prefixes to search through in * addition by defining the java.content.handler.pkgs property. * The class name must be of the form: *

 *     {package-prefix}.{major}.{minor}
 * e.g.
 *     YoyoDyne.experimental.text.plain
 * 
* If the loading of the content handler class would be performed by * a classloader that is outside of the delegation chain of the caller, * the JVM will need the RuntimePermission "getClassLoader". * * @author James Gosling * @see java.net.ContentHandler#getContent(java.net.URLConnection) * @see java.net.ContentHandlerFactory * @see java.net.URL#getContent() * @see java.net.URLConnection * @see java.net.URLConnection#getContent() * @see java.net.URLConnection#setContentHandlerFactory(java.net.ContentHandlerFactory) * @since JDK1.0 */ abstract public class ContentHandler { /** * Given a URL connect stream positioned at the beginning of the * representation of an object, this method reads that stream and * creates an object from it. * * @param urlc a URL connection. * @return the object read by the ContentHandler. * @exception IOException if an I/O error occurs while reading the object. */ abstract public Object getContent(URLConnection urlc) throws IOException; /** * Given a URL connect stream positioned at the beginning of the * representation of an object, this method reads that stream and * creates an object that matches one of the types specified. * * The default implementation of this method should call getContent() * and screen the return type for a match of the suggested types. * * @param urlc a URL connection. * @param classes an array of types requested * @return the object read by the ContentHandler that is * the first match of the suggested types. * null if none of the requested are supported. * @exception IOException if an I/O error occurs while reading the object. * @since 1.3 */ public Object getContent(URLConnection urlc, Class[] classes) throws IOException { Object obj = getContent(urlc); for (int i = 0; i < classes.length; i++) { if (classes[i].isInstance(obj)) { return obj; } } return null; } }