Source for gnu.xml.libxmlj.util.NamedInputStream

   1: /* NamedInputStream.java -
   2:    Copyright (C) 2004 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: package gnu.xml.libxmlj.util;
  39: 
  40: import java.io.FilterInputStream;
  41: import java.io.InputStream;
  42: import java.io.IOException;
  43: import java.io.PushbackInputStream;
  44: 
  45: /**
  46:  * An input stream associated with an XML system ID.
  47:  * It can report the system ID and the first few bytes of the stream
  48:  * in order to detect the character encoding of the stream.
  49:  *
  50:  * @author <a href='dog@gnu.org'>Chris Burdess</a>
  51:  */
  52: public class NamedInputStream
  53: extends FilterInputStream
  54: {
  55: 
  56:   private static int DETECT_BUFFER_SIZE = 50;
  57: 
  58:   private String name;
  59: 
  60:   NamedInputStream (String name, InputStream in, int size)
  61:   {
  62:     super (new PushbackInputStream (in, size));
  63:     this.name = name;
  64:   }
  65: 
  66:   /**
  67:    * Returns the name of the stream (the XML system ID).
  68:    */
  69:   public String getName ()
  70:   {
  71:     return name;
  72:   }
  73: 
  74:   /**
  75:    * Returns the first few bytes of the stream for character encoding
  76:    * purposes. The entire stream can thereafter be read normally from the
  77:    * beginning. This method is only valid if no bytes have yet been read
  78:    * from the stream.
  79:    */
  80:   public byte[] getDetectBuffer ()
  81:     throws IOException
  82:   {
  83:     PushbackInputStream p = (PushbackInputStream) in;
  84:     byte[] buffer = new byte[DETECT_BUFFER_SIZE];
  85:     int len = p.read (buffer);
  86:     if (len < 0)
  87:       {
  88:         return null;
  89:       }
  90:     else
  91:       {
  92:         p.unread (buffer, 0, len);
  93:         byte[] ret = new byte[len];
  94:         System.arraycopy (buffer, 0, ret, 0, len);
  95:         return ret;
  96:       }
  97:   }
  98: 
  99: }