Convert lines into the canonical MIME format, that is, terminate lines with CRLF : Formatter « Email « Java Tutorial

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/*
 * @(#)CRLFOutputStream.java  1.3 01/05/23
 *
 * Copyright 1997-2000 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * 
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND
 * ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES OR LIABILITIES
 * SUFFERED BY LICENSEE AS A RESULT OF  OR RELATING TO USE, MODIFICATION
 * OR DISTRIBUTION OF THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL
 * SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR
 * FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
 * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
 * ARISING OUT OF THE USE OF OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS
 * BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 * 
 * You acknowledge that Software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * Convert lines into the canonical MIME format, that is, terminate lines with
 * CRLF.
 * <P>
 * 
 * This stream can be used with the Part.writeTo and Message.writeTo methods to
 * generate the canonical MIME format of the data for the purpose of (e.g.)
 * sending it via SMTP or computing a digital signature.
 */
public class CRLFOutputStream extends FilterOutputStream {
  protected int lastb = -1;

  protected static byte[] newline;
  static {
    newline = new byte[2];
    newline[0] = (byte) '\r';
    newline[1] = (byte) '\n';
  }

  public CRLFOutputStream(OutputStream os) {
    super(os);
  }

  public void write(int b) throws IOException {
    if (b == '\r') {
      out.write(newline);
    } else if (b == '\n') {
      if (lastb != '\r')
        out.write(newline);
    } else {
      out.write(b);
    }
    lastb = b;
  }

  public void write(byte b[]) throws IOException {
    write(b, 0, b.length);
  }

  public void write(byte b[], int off, int len) throws IOException {
    int start = off;

    len += off;
    for (int i = start; i < len; i++) {
      if (b[i] == '\r') {
        out.write(b, start, i - start);
        out.write(newline);
        start = i + 1;
      } else if (b[i] == '\n') {
        if (lastb != '\r') {
          out.write(b, start, i - start);
          out.write(newline);
        }
        start = i + 1;
      }
      lastb = b[i];
    }
    if ((len - start) > 0)
      out.write(b, start, len - start);
  }
}