demo/src/main/java/CRLFOutputStream.java

/*
 * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

import java.io.*;

/**
 * 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);
    }
}