base64.java

jxme的一些相关程序,主要是手机上程序开发以及手机和计算机通信的一些程序资料,程序编译需要Ant支持

/************************************************************************
 *
 * $Id: Base64.java,v 1.2 2002/03/04 21:43:01 echtcherbina Exp $
 *
 * Copyright (c) 2001 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:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
 *    must not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 *********************************************************************************/

package net.jxta.impl.util;
    
import java.io.IOException;
import java.io.StringReader;
import java.io.ByteArrayOutputStream;
import java.io.StringWriter;

public class Base64 {
    
    private Base64() {
    }
    
    
    
    // Base64 encoding.  See Rfc1341

    static public byte[] decodeBase64(String text) 
        throws IOException
    {
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        StringReader r = new StringReader(text);
        
        for(;;) {
            char c0 = getBase64Char(r);
            if (c0 == '\0')
                break;
            char c1 = getBase64Char(r);
            if (c1 == '\0')
                throw new IOException("binary data not a multiple of four bytes");
            char c2 = getBase64Char(r);
            if (c2 == '\0')
                throw new IOException("binary data not a multiple of four bytes");
            char c3 = getBase64Char(r);
            if (c3 == '\0')
                throw new IOException("binary data not a multiple of four bytes");

            if (c0 == '=')
                throw new IOException("'=' found in first position of base64 data");
            if (c1 == '=')
                throw new IOException("'=' found in second position of base64 data");
            int n = 3;
            if (c2 == '=') {
                n = 1;
                c2 = c3 = 'A'; // So we get a value of 0.
            } else
            if (c3 == '=') {
                n = 2;
                c3 = 'A'; // So we get a value of 0.
            }

            int v = (decodeSixBits(c0)<<18)
                  + (decodeSixBits(c1)<<12)
                  + (decodeSixBits(c2)<< 6)
                  +  decodeSixBits(c3);

            int b0 = (v>>16)&0xff;
            int b1 = (v>> 8)&0xff;
            int b2 = (v    )&0xff;
            os.write(b0);
            if (n >= 2)
                os.write(b1);
            if (n == 3)
                os.write(b2);
        }
        
        return os.toByteArray();
    }

    /**
     * '\0' represents end of file.
     */
    static private char getBase64Char(StringReader r)
        throws IOException
    {
        for(;;) {
            int i = r.read();
            if (i == -1)
                return '\0';

            char c = (char)i;
            if ('A' <= c && c <= 'Z')
                return c;
            else
            if ('a' <= c && c <= 'z')
                return c;
            else
            if ('0' <= c && c <= '9')
                return c;
            else
            if (c == '+')
                return c;
            else
            if (c == '/')
                return c;
            else
            if (c == '=')
                return c;
            
            // Not a base64 char, loop around and try again.
            
        }
    }
    
    static public String encodeBase64(byte[] bytes)
    {
        int n = 0;
        StringWriter w = new StringWriter();
        int v;
        int h;  // Six bits.  Six, thus h for hex.
        
        int len = bytes.length/3*3;
        for(int i=0; i<len; i += 3) {
            v = (bytes[i]<<16) + ((bytes[i+1]&0xff)<<8) + (bytes[i+2]&0xff);
            
            h = (v >> 18)&0x3f;
            w.write(encodeSixBits(h));
            
            h = ((v >> 12)&0x3f);
            w.write(encodeSixBits(h));
            
            h = ((v >> 6)&0x3f);
            w.write(encodeSixBits(h));
            
            h = ((v >> 0)&0x3f);
            w.write(encodeSixBits(h));
            
            n += 4;
            if (n >= 76) {
                w.write("\r\n");
                n = 0;
            }
            
        }
        
        switch(bytes.length - len) {
            case 0:
                break;
            case 1:
                v = (bytes[len]<<16);
                
                h = (v >> 18)&0x3f;
                w.write(encodeSixBits(h));

                h = (v >> 12)&0x3f;
                w.write(encodeSixBits(h));
                
                w.write('=');
                w.write('=');
                break;
            case 2:
                v = (bytes[len]<<16) + ((bytes[len+1]&0xff)<<8);

                h = (v >> 18)&0x3f;
                w.write(encodeSixBits(h));

                h = ((v >> 12)&0x3f);
                w.write(encodeSixBits(h));

                h = ((v >> 6)&0x3f);                
                w.write(encodeSixBits(h));
                
                w.write('=');
                break;
        }
        w.write("\r\n");
        return w.toString();
    }
    
            
    static private char encodeSixBits(int b)
    {
        char c;

        if (b <= 25)
            c = (char)('A' + b);
        else
        if (b <= 51)
            c = (char)('a' + b-26);
        else
        if (b <= 61)
            c = (char)('0' + b-52);
        else
        if (b == 62)
            c = '+';
        else
        //if (b == 63)
            c = '/';
        return c;
    }

    static private int decodeSixBits(char c) {
        int v;
        
        if ('A' <= c && c <= 'Z')
            v = (int)(c-'A');
        else
        if ('a' <= c && c <= 'z')
            v = (int)(c-'a')+ 26;
        else
        if ('0' <= c && c <= '9')
            v = (int)(c - '0') + 52;
        else
        if (c == '+')
            v = 62;
        else
        //if (c == '/')
            v = 63;

        return v;
    }
    
    public static void main(String args[])
    {
        byte bytes[] = new byte[200];
        
        for(int i=0; i<bytes.length; ++i)
            bytes[i] = (byte)i;
        
        System.out.println(encodeBase64(bytes));
    }
}