/* * 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 <code>ContentHandler</code> is the superclass * of all classes that read an <code>Object</code> from a * <code>URLConnection</code>. * <p> * An application does not generally call the * <code>getContent</code> method in this class directly. Instead, an * application calls the <code>getContent</code> method in class * <code>URL</code> or in <code>URLConnection</code>. * The application's content handler factory (an instance of a class that * implements the interface <code>ContentHandlerFactory</code> set * up by a call to <code>setContentHandler</code>) is * called with a <code>String</code> giving the MIME type of the * object being received on the socket. The factory returns an * instance of a subclass of <code>ContentHandler</code>, and its * <code>getContent</code> method is called to create the object. * <p> * 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: * <pre> *     {package-prefix}.{major}.{minor} * e.g. *     YoyoDyne.experimental.text.plain * </pre> * 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 <code>ContentHandler</code>.     * @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 <code>ContentHandler</code> 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;    } }