Java Base64 Decode base64Decode(String s)

Description

Decodes a byte array from Base64 format.

License

Open Source License

Parameter

Parameter	Description
in	A character array containing the Base64 encoded data.
iOff	Offset of the first character in <code>in</code> to be processed.
iLen	Number of characters to process in <code>in</code>, starting at <code>iOff</code>.

Exception

Parameter	Description
IllegalArgumentException	If the input is not valid Base64 encoded data.

Return

An array containing the decoded data bytes.

Declaration

public static byte[] base64Decode(String s) 

Method Source Code

//package com.java2s;
/*//from   w w w . j  a  v  a 2  s.c o  m
 * Copyright 2003-2010 Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland
 * www.source-code.biz, www.inventec.ch/chdh
 * 
 * This module is multi-licensed and may be used under the terms of any of the following licenses:
 * 
 * EPL, Eclipse Public License, V1.0 or later, http://www.eclipse.org/legal
 * LGPL, GNU Lesser General Public License, V2.1 or later, http://www.gnu.org/licenses/lgpl.html
 * GPL, GNU General Public License, V2 or later, http://www.gnu.org/licenses/gpl.html
 * AL, Apache License, V2.0 or later, http://www.apache.org/licenses
 * BSD, BSD License, http://www.opensource.org/licenses/bsd-license.php
 * MIT, MIT License, http://www.opensource.org/licenses/MIT
 * 
 * Please contact the author if you need another license.
 * This module is provided "as is", without warranties of any kind.
 * 
 * For the purposes of Mace Swinger, we are using the MIT license
 */

public class Main {
    private static final byte[] map2 = new byte[128];

    /**
     * Decodes a byte array from Base64 format. No blanks or line breaks are allowed within the Base64 encoded input data.
     * 
     * @param in
     *            A character array containing the Base64 encoded data.
     * @param iOff
     *            Offset of the first character in <code>in</code> to be processed.
     * @param iLen
     *            Number of characters to process in <code>in</code>, starting at <code>iOff</code>.
     * @return An array containing the decoded data bytes.
     * @throws IllegalArgumentException
     *             If the input is not valid Base64 encoded data.
     */
    public static byte[] base64Decode(String s) {
        char[] in = s.toCharArray();
        int iOff = 0;
        int iLen = s.toCharArray().length;
        if (iLen % 4 != 0)
            throw new IllegalArgumentException("Length of Base64 encoded input string is not a multiple of 4.");
        while (iLen > 0 && in[iOff + iLen - 1] == '=')
            iLen--;
        int oLen = (iLen * 3) / 4;
        byte[] out = new byte[oLen];
        int ip = iOff;
        int iEnd = iOff + iLen;
        int op = 0;
        while (ip < iEnd) {
            int i0 = in[ip++];
            int i1 = in[ip++];
            int i2 = ip < iEnd ? in[ip++] : 'A';
            int i3 = ip < iEnd ? in[ip++] : 'A';
            if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
                throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
            int b0 = map2[i0];
            int b1 = map2[i1];
            int b2 = map2[i2];
            int b3 = map2[i3];
            if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
                throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
            int o0 = (b0 << 2) | (b1 >>> 4);
            int o1 = ((b1 & 0xf) << 4) | (b2 >>> 2);
            int o2 = ((b2 & 3) << 6) | b3;
            out[op++] = (byte) o0;
            if (op < oLen)
                out[op++] = (byte) o1;
            if (op < oLen)
                out[op++] = (byte) o2;
        }
        return out;
    }
}

Related

1. base64Decode(String base64Str)
2. base64Decode(String data)
3. base64Decode(String input)
4. base64Decode(String s)
5. base64Decode(String s)
6. base64decode(String s)
7. base64Decode(String str)
8. base64Decode(String str)
9. Base64Decode(String str)