127 lines
4.6 KiB
Java
127 lines
4.6 KiB
Java
/* ContentHandler.java -- Abstract class for handling content from URL's
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Copyright (C) 1998, 1999, 2000, 2001, 2003 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.net;
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import java.io.IOException;
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/**
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* Written using on-line Java Platform 1.2 API Specification, as well
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* as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
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* Status: Believed complete and correct.
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*/
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/**
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* This is an abstract class that is the superclass for classes that read
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* objects from URL's. Calling the <code>getContent()</code> method in the
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* <code>URL</code> class or the <code>URLConnection</code> class will cause
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* an instance of a subclass of <code>ContentHandler</code> to be created for
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* the MIME type of the object being downloaded from the URL. Thus, this
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* class is seldom needed by applications/applets directly, but only
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* indirectly through methods in other classes.
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*
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* @author Aaron M. Renn (arenn@urbanophile.com)
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* @author Warren Levy (warrenl@cygnus.com)
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*/
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public abstract class ContentHandler
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{
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/*
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* Constructors
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*/
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/**
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* Default, no-argument constructor.
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*/
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public ContentHandler()
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{
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}
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/*
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* Instance Methods
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*/
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/**
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* This method reads from the <code>InputStream</code> of the passed in URL
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* connection and uses the data downloaded to create an <code>Object</code>
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* represening the content. For example, if the URL is pointing to a GIF
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* file, this method might return an <code>Image</code> object. This method
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* must be implemented by subclasses.
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*
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* @param urlc A <code>URLConnection</code> object to read data from.
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*
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* @return An object representing the data read
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*
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* @exception IOException If an error occurs
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*/
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public abstract Object getContent(URLConnection urlc)
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throws IOException;
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/**
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* This method reads from the <code>InputStream</code> of the passed in URL
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* connection and uses the data downloaded to create an <code>Object</code>
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* represening the content. For example, if the URL is pointing to a GIF
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* file, this method might return an <code>Image</code> object. This method
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* must be implemented by subclasses. This method uses the list of
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* supplied classes as candidate types. If the data read doesn't match
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* any of the supplied type, <code>null</code> is returned.
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*
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* @param urlc A <code>URLConnection</code> object to read data from.
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* @param classes An array of types of objects that are candidate types
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* for the data to be read.
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*
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* @return An object representing the data read, or <code>null</code>
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* if the data does not match any of the candidate types.
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*
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* @exception IOException If an error occurs
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*
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* @since 1.3
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*/
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public Object getContent(URLConnection urlc, Class[] classes)
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throws IOException
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{
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Object obj = getContent(urlc);
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for (int i = 0; i < classes.length; i++)
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{
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if (classes[i].isInstance(obj))
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return obj;
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}
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return null;
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}
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} // class ContentHandler
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