Base64

天云上人

import java.lang.*;
import java.io.*;
  
public class Base64 {
    private static char[] base64EncodeChars = new char[] {
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
        'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
        'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
        'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
        'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
        'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
        'w', 'x', 'y', 'z', '0', '1', '2', '3',
        '4', '5', '6', '7', '8', '9', '+', '/' };
  
    private static byte[] base64DecodeChars = new byte[] {
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
    -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
    -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 };
  
    public static String encode(byte[] data) {
        StringBuffer sb = new StringBuffer();
        int len = data.length;
        int i = 0;
        int b1, b2, b3;
        while (i < len) {
            b1 = data[i++] & 0xff;
            if (i == len)
            {
                sb.append(base64EncodeChars[b1 >>> 2]);
                sb.append(base64EncodeChars[(b1 & 0x3) << 4]);
                sb.append("==");
                break;
            }
            b2 = data[i++] & 0xff;
            if (i == len)
            {
                sb.append(base64EncodeChars[b1 >>> 2]);
                sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
                sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
                sb.append("=");
                break;
            }
            b3 = data[i++] & 0xff;
            sb.append(base64EncodeChars[b1 >>> 2]);
            sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
            sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);
            sb.append(base64EncodeChars[b3 & 0x3f]);
        }
        return sb.toString();
    }
  
    public static byte[] decode(String str) throws UnsupportedEncodingException {
        StringBuffer sb = new StringBuffer();
        byte[] data = str.getBytes("US-ASCII");
        int len = data.length;
        int i = 0;
        int b1, b2, b3, b4;
        while (i < len) {
            /* b1 */
            do {
                b1 = base64DecodeChars[data[i++]];
            } while (i < len && b1 == -1);
            if (b1 == -1) break;
            /* b2 */
            do {
                b2 = base64DecodeChars[data[i++]];
            } while (i < len && b2 == -1);
            if (b2 == -1) break;
            sb.append((char)((b1 << 2) | ((b2 & 0x30) >>> 4)));
            /* b3 */
            do {
                b3 = data[i++];
                if (b3 == 61) return sb.toString().getBytes("ISO-8859-1");
                b3 = base64DecodeChars[b3];
            } while (i < len && b3 == -1);
            if (b3 == -1) break;
            sb.append((char)(((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));
            /* b4 */
            do {
                b4 = data[i++];
                if (b4 == 61) return sb.toString().getBytes("ISO-8859-1");
                b4 = base64DecodeChars[b4];
            } while (i < len && b4 == -1);
            if (b4 == -1) break;
            sb.append((char)(((b3 & 0x03) << 6) | b4));
        }
        return sb.toString().getBytes("ISO-8859-1");
    }
}

天云上人

package com.meterware.httpunit;
/********************************************************************************************************************
* $Id: Base64.java,v 1.4 2002/12/24 15:17:17 russgold Exp $
*
* Copyright (c) 2000-2002 by Russell Gold
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
* documentation files (the "Software"), to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and
* to permit persons to whom the Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
* THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
*******************************************************************************************************************/

/**
* A utility class to convert to and from base 64 encoding.
*
* @author <a href="mailto:russgold@httpunit.org">Russell Gold</a>
**/
public class Base64 {

    final static String encodingChar = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";


    /**
     * Returns the base 64 encoded equivalent of a supplied string.
     * @param source the string to encode
     */
    public static String encode( String source ) {
        char[] sourceBytes = getPaddedBytes( source );
        int numGroups = (sourceBytes.length + 2) / 3;
        char[] targetBytes = new char[4];
        char[] target = new char[ 4 * numGroups ];

        for (int group = 0; group < numGroups; group++) {
            convert3To4( sourceBytes, group*3, targetBytes );
            for (int i = 0; i < targetBytes.length; i++) {
                target[ i + 4*group ] = encodingChar.charAt( targetBytes[i] );
            }
        }

        int numPadBytes = sourceBytes.length - source.length();

        for (int i = target.length-numPadBytes; i < target.length; i++) target[i] = '=';
        return new String( target );
    }


    private static char[] getPaddedBytes( String source ) {
        char[] converted = source.toCharArray();
        int requiredLength = 3 * ((converted.length+2) /3);
        char[] result = new char[ requiredLength ];
        System.arraycopy( converted, 0, result, 0, converted.length );
        return result;
    }


    private static void convert3To4( char[] source, int sourceIndex, char[] target ) {
        target[0] = (char) ( source[ sourceIndex ] >>> 2);
        target[1] = (char) (((source[ sourceIndex   ] & 0x03) << 4) | (source[ sourceIndex+1 ] >>> 4));
        target[2] = (char) (((source[ sourceIndex+1 ] & 0x0f) << 2) | (source[ sourceIndex+2 ] >>> 6));
        target[3] = (char) (  source[ sourceIndex+2 ] & 0x3f);
    }


    /**
     * Returns the plaintext equivalent of a base 64-encoded string.
     * @param source a base 64 string (which must have a multiple of 4 characters)
     */
    public static String decode( String source ) {
        if (source.length()%4 != 0) throw new RuntimeException( "valid Base64 codes have a multiple of 4 characters" );
        int numGroups = source.length() / 4;
        int numExtraBytes = source.endsWith( "==" ) ? 2 : (source.endsWith( "=" ) ? 1 : 0);
        byte[] targetBytes = new byte[ 3*numGroups ];
        byte[] sourceBytes = new byte[4];
        for (int group = 0; group < numGroups; group++) {
            for (int i = 0; i < sourceBytes.length; i++) {
                sourceBytes[i] = (byte) Math.max( 0, encodingChar.indexOf( source.charAt( 4*group+i ) ) );
            }
            convert4To3( sourceBytes, targetBytes, group*3 );
        }
        return new String( targetBytes, 0, targetBytes.length - numExtraBytes );
    }


    private static void convert4To3( byte[] source, byte[] target, int targetIndex ) {
        target[ targetIndex  ]  = (byte) (( source[0] << 2) | (source[1] >>> 4));
        target[ targetIndex+1 ] = (byte) (((source[1] & 0x0f) << 4) | (source[2] >>> 2));
        target[ targetIndex+2 ] = (byte) (((source[2] & 0x03) << 6) | (source[3]));
    }

}