Initial revision

From-SVN: r102074

libjava/classpath/java/net/ContentHandler.java

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+/* ContentHandler.java -- Abstract class for handling content from URL's
+   Copyright (C) 1998, 1999, 2000, 2001, 2003 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package java.net;
+
+import java.io.IOException;
+
+/**
+ * Written using on-line Java Platform 1.2 API Specification, as well
+ * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
+ * Status:  Believed complete and correct.
+ */
+
+/**
+  * This is an abstract class that is the superclass for classes that read
+  * objects from URL's.  Calling the <code>getContent()</code> method in the
+  * <code>URL</code> class or the <code>URLConnection</code> class will cause
+  * an instance of a subclass of <code>ContentHandler</code> to be created for
+  * the MIME type of the object being downloaded from the URL.  Thus, this
+  * class is seldom needed by applications/applets directly, but only
+  * indirectly through methods in other classes.
+  *
+  * @author Aaron M. Renn (arenn@urbanophile.com)
+  * @author Warren Levy (warrenl@cygnus.com)
+  */
+public abstract class ContentHandler
+{
+  /*
+   * Constructors
+   */
+
+  /**
+    * Default, no-argument constructor.
+    */
+  public ContentHandler()
+  {
+  }
+
+  /*
+   * Instance Methods
+   */
+
+  /**
+    * This method reads from the <code>InputStream</code> of the passed in URL
+    * connection and uses the data downloaded to create an <code>Object</code>
+    * represening the content.  For example, if the URL is pointing to a GIF
+    * file, this method might return an <code>Image</code> object.  This method
+    * must be implemented by subclasses.
+    *
+    * @param urlc A <code>URLConnection</code> object to read data from.
+    *
+    * @return An object representing the data read
+    *
+    * @exception IOException If an error occurs
+    */
+  public abstract Object getContent(URLConnection urlc)
+    throws IOException;
+
+  /**
+    * This method reads from the <code>InputStream</code> of the passed in URL
+    * connection and uses the data downloaded to create an <code>Object</code>
+    * represening the content.  For example, if the URL is pointing to a GIF
+    * file, this method might return an <code>Image</code> object.  This method
+    * must be implemented by subclasses.  This method uses the list of
+    * supplied classes as candidate types.  If the data read doesn't match
+    * any of the supplied type, <code>null</code> is returned.
+    *
+    * @param urlc A <code>URLConnection</code> object to read data from.
+    * @param classes An array of types of objects that are candidate types
+    * for the data to be read.
+    *
+    * @return An object representing the data read, or <code>null</code>
+    * if the data does not match any of the candidate types.
+    *
+    * @exception IOException If an error occurs
+    *
+    * @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;
+  }
+} // class ContentHandler