Main.java Source code

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Here is the source code for Main.java

Source

//package com.java2s;
// and/or modify it under the terms of the GNU General Public License 

public class Main {
    /**
     * Convert Base64 string to byte array.
     * 
     * @param input
     *            Base64 string.
     * @return Converted byte array.
     */
    public static byte[] fromBase64(final String input) {
        String tmp = input.replace("\r\n", "");
        if (tmp.length() % 4 != 0) {
            throw new IllegalArgumentException("Invalid base64 input");
        }
        int len = (tmp.length() * 3) / 4;
        int pos = tmp.indexOf('=');
        if (pos > 0) {
            len -= tmp.length() - pos;
        }
        byte[] decoded = new byte[len];
        char[] inChars = new char[4];
        int j = 0;
        int[] b = new int[4];
        for (pos = 0; pos != tmp.length(); pos += 4) {
            tmp.getChars(pos, pos + 4, inChars, 0);
            b[0] = getIndex(inChars[0]);
            b[1] = getIndex(inChars[1]);
            b[2] = getIndex(inChars[2]);
            b[3] = getIndex(inChars[3]);
            decoded[j++] = (byte) ((b[0] << 2) | (b[1] >> 4));
            if (b[2] < 64) {
                decoded[j++] = (byte) ((b[1] << 4) | (b[2] >> 2));
                if (b[3] < 64) {
                    decoded[j++] = (byte) ((b[2] << 6) | b[3]);
                }
            }
        }
        return decoded;
    }

    /**
     * Get index of given char.
     * 
     * @param ch
     * @return
     */
    private static int getIndex(final char ch) {
        if (ch == '+') {
            return 62;
        }
        if (ch == '/') {
            return 63;
        }
        if (ch == '=') {
            return 64;
        }
        if (ch < ':') {
            return (52 + (ch - '0'));
        }
        if (ch < '[') {
            return (ch - 'A');
        }
        if (ch < '{') {
            return (26 + (ch - 'a'));
        }
        throw new IllegalArgumentException("fromBase64");
    }
}