Source for gnu.inet.util.CRLFOutputStream

   1: /*
   2:  * CRLFOutputStream.java
   3:  * Copyright (C) 2002 The Free Software Foundation
   4:  * 
   5:  * This file is part of GNU inetlib, a library.
   6:  * 
   7:  * GNU inetlib is free software; you can redistribute it and/or modify
   8:  * it under the terms of the GNU General Public License as published by
   9:  * the Free Software Foundation; either version 2 of the License, or
  10:  * (at your option) any later version.
  11:  * 
  12:  * GNU inetlib is distributed in the hope that it will be useful,
  13:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15:  * GNU General Public License for more details.
  16:  * 
  17:  * You should have received a copy of the GNU General Public License
  18:  * along with this library; if not, write to the Free Software
  19:  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  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:  * obliged to do so.  If you do not wish to do so, delete this
  36:  * exception statement from your version.
  37:  */
  38: 
  39: package gnu.inet.util;
  40: 
  41: import java.io.FilterOutputStream;
  42: import java.io.IOException;
  43: import java.io.OutputStream;
  44: import java.io.UnsupportedEncodingException;
  45: 
  46: /** 
  47:  * An output stream that filters LFs into CR/LF pairs.
  48:  *
  49:  * @author <a href="mailto:dog@gnu.org">Chris Burdess</a>
  50:  */
  51: public class CRLFOutputStream
  52:   extends FilterOutputStream
  53: {
  54: 
  55:   static final String US_ASCII = "US-ASCII";
  56: 
  57:   /**
  58:    * The CR octet.
  59:    */
  60:   public static final int CR = 13;
  61: 
  62:   /**
  63:    * The LF octet.
  64:    */
  65:   public static final int LF = 10;
  66: 
  67:   /**
  68:    * The CR/LF pair.
  69:    */
  70:   public static final byte[] CRLF = { CR, LF };
  71: 
  72:   /**
  73:    * The last byte read.
  74:    */
  75:   protected int last;
  76: 
  77:   /**
  78:    * Constructs a CR/LF output stream connected to the specified output stream.
  79:    */
  80:   public CRLFOutputStream(OutputStream out)
  81:   {
  82:     super(out);
  83:     last = -1;
  84:   }
  85: 
  86:   /**
  87:    * Writes a character to the underlying stream.
  88:    * @exception IOException if an I/O error occurred
  89:    */
  90:   public void write(int ch) throws IOException
  91:   {
  92:     if (ch == CR)
  93:       {
  94:         out.write(CRLF);
  95:       }
  96:     else if (ch == LF)
  97:       {
  98:         if (last != CR)
  99:           {
 100:             out.write(CRLF);
 101:           }
 102:       }
 103:     else
 104:       {
 105:         out.write(ch);
 106:       }
 107:     last = ch;
 108:   }
 109:   
 110:   /**
 111:    * Writes a byte array to the underlying stream.
 112:    * @exception IOException if an I/O error occurred
 113:    */
 114:   public void write(byte[] b)
 115:     throws IOException
 116:   {
 117:     write(b, 0, b.length);
 118:   }
 119: 
 120:   /**
 121:    * Writes a portion of a byte array to the underlying stream.
 122:    * @exception IOException if an I/O error occurred
 123:    */
 124:   public void write(byte[] b, int off, int len)
 125:     throws IOException
 126:   {
 127:     int d = off;
 128:     len += off;
 129:     for (int i = off; i < len; i++)
 130:       {
 131:         switch (b[i])
 132:           {
 133:           case CR:
 134:             out.write (b, d, i - d);
 135:             out.write (CRLF, 0, 2);
 136:             d = i + 1;
 137:             break;
 138:           case LF:
 139:             if (last != CR)
 140:               {
 141:                 out.write (b, d, i - d);
 142:                 out.write (CRLF, 0, 2);
 143:               }
 144:             d = i + 1;
 145:             break;
 146:           }
 147:         last = b[i];
 148:       }
 149:     if (len - d > 0)
 150:       {
 151:         out.write (b, d, len - d);
 152:       }
 153:   }
 154:   
 155:   /**
 156:    * Writes the specified ASCII string to the underlying stream.
 157:    * @exception IOException if an I/O error occurred
 158:    */
 159:   public void write(String text)
 160:     throws IOException
 161:   {
 162:     try
 163:       {
 164:         byte[] bytes = text.getBytes(US_ASCII);
 165:         write(bytes, 0, bytes.length);
 166:         }
 167:     catch (UnsupportedEncodingException e)
 168:       {
 169:         throw new IOException("The US-ASCII encoding is not supported " +
 170:                               "on this system");
 171:       }
 172:   }
 173: 
 174:   /**
 175:    * Writes a newline to the underlying stream.
 176:    * @exception IOException if an I/O error occurred
 177:    */
 178:   public void writeln()
 179:     throws IOException
 180:   {
 181:     out.write(CRLF, 0, 2);
 182:   }
 183: 
 184: }