crlfinputstream.java

来自「kaffe Java 解释器语言,源码,Java的子集系统,开放源代码」· Java 代码 · 共 191 行

/*
 * $Id: CRLFInputStream.java,v 1.1 2004/01/10 23:34:31 dalibor Exp $
 * Copyright (C) 2002 The Free Software Foundation
 * 
 * This file is part of GNU inetlib, a library.
 * 
 * GNU inetlib 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 of the License, or
 * (at your option) any later version.
 * 
 * GNU inetlib 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 this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * As a special exception, if you link this library with other files to
 * produce an executable, this library does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * This exception does not however invalidate any other reasons why the
 * executable file might be covered by the GNU General Public License.
 */

package gnu.inet.util;

import java.io.FilterInputStream;
import java.io.InputStream;
import java.io.IOException;

/**
 * An input stream that filters out CR/LF pairs into LFs.
 *
 * @author <a href="mailto:[e-mail]">Chris Burdess</a>
 * @version $Revision: 1.1 $ $Date: 2004/01/10 23:34:31 $
 */
public class CRLFInputStream extends FilterInputStream
{

  /**
   * The CR octet.
   */
  public static final int CR = 13;

  /**
   * The LF octet.
   */
  public static final int LF = 10;

        /**
	 * Buffer.
	 */
  protected int buf = -1;

        /**
	 * Buffer at time of mark.
	 */
  protected int markBuf = -1;

  /**
   * Constructs a CR/LF input stream connected to the specified input
   * stream.
   */
  public CRLFInputStream(InputStream in)
  {
    super(in);
  }

  /**
   * Reads the next byte of data from this input stream.
   * Returns -1 if the end of the stream has been reached.
   * @exception IOException if an I/O error occurs
   */
  public int read() throws IOException
  {
    int c;
    if (buf != -1)
    {
      c = buf;
      buf = -1;
      return c;
    }
    else
    {
      c = super.read();
      if (c == CR)
      {
        buf = super.read();
        if (buf == LF)
        {
          c = buf;
          buf = -1;
        }
      }
    }
    return c;
  }

  /**
   * Reads up to b.length bytes of data from this input stream into
   * an array of bytes.
   * Returns -1 if the end of the stream has been reached.
   * @exception IOException if an I/O error occurs
   */
  public int read(byte[]b) throws IOException
  {
    return read(b, 0, b.length);
  }

  /**
   * Reads up to len bytes of data from this input stream into an
   * array of bytes, starting at the specified offset.
   * Returns -1 if the end of the stream has been reached.
   * @exception IOException if an I/O error occurs
   */
  public int read(byte[]b, int off, int len) throws IOException
  {
    int shift = 0;
    if (buf != -1)
    {
      // Push buf onto start of byte array
      b[off] = (byte) buf;
      off++;
      len--;
      buf = -1;
      shift++;
    }
    int l = super.read(b, off, len);
    l = removeCRLF(b, off - shift, l);
    return l;
  }

        /**
	 * Indicates whether this stream supports the mark and reset methods.
	 */
  public boolean markSupported()
  {
    return in.markSupported();
  }

        /**
	 * Marks the current position in this stream.
	 */
  public void mark(int readlimit)
  {
    in.mark(readlimit);
    markBuf = buf;
  }

        /**
	 * Repositions this stream to the position at the time the mark method was
	 * called.
	 */
  public void reset() throws IOException
  {
    in.reset();
    buf = markBuf;
  }

  private int removeCRLF(byte[]b, int off, int len)
  {
    int end = off + len;
    for (int i = off; i < end; i++)
    {
      if (b[i] == CR)
      {
        if (i + 1 == end)
        {
          // This is the last byte, impossible to determine whether CRLF
          buf = CR;
          len--;
        }
        else if (b[i + 1] == LF)
        {
          // Shift left
          end--;
          for (int j = i; j < end; j++)
            b[j] = b[j + 1];
          len--;
          end = off + len;
        }
      }
    }
    return len;
  }

}