Android Base64 Decode decode(char[] arr)

Description

decode

Declaration

public static byte[] decode(char[] arr) 

Method Source Code

//package com.java2s;

public class Main {
    private static final int[] INV = new int[256];

    public static byte[] decode(char[] arr) {
        int length = arr.length;
        if (length == 0)
            return new byte[0];

        int sndx = 0, endx = length - 1;
        int pad = arr[endx] == '=' ? (arr[endx - 1] == '=' ? 2 : 1) : 0;
        int cnt = endx - sndx + 1;
        int sepCnt = length > 76 ? (arr[76] == '\r' ? cnt / 78 : 0) << 1
                : 0;//from w  w  w  .  java  2  s.  c o m
        int len = ((cnt - sepCnt) * 6 >> 3) - pad;
        byte[] dest = new byte[len];

        int d = 0;
        for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
            int i = INV[arr[sndx++]] << 18 | INV[arr[sndx++]] << 12
                    | INV[arr[sndx++]] << 6 | INV[arr[sndx++]];
            dest[d++] = (byte) (i >> 16);
            dest[d++] = (byte) (i >> 8);
            dest[d++] = (byte) i;
            if (sepCnt > 0 && ++cc == 19) {
                sndx += 2;
                cc = 0;
            }
        }

        if (d < len) {
            int i = 0;
            for (int j = 0; sndx <= endx - pad; j++) {
                i |= INV[arr[sndx++]] << (18 - j * 6);
            }
            for (int r = 16; d < len; r -= 8) {
                dest[d++] = (byte) (i >> r);
            }
        }

        return dest;
    }

    /**
     * Decodes a BASE64 encoded byte array.
     */
    public static byte[] decode(byte[] arr) {
        int length = arr.length;
        if (length == 0) {
            return new byte[0];
        }

        int sndx = 0, endx = length - 1;
        int pad = arr[endx] == '=' ? (arr[endx - 1] == '=' ? 2 : 1) : 0;
        int cnt = endx - sndx + 1;
        int sepCnt = length > 76 ? (arr[76] == '\r' ? cnt / 78 : 0) << 1
                : 0;
        int len = ((cnt - sepCnt) * 6 >> 3) - pad;
        byte[] dest = new byte[len];

        int d = 0;
        for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
            int i = INV[arr[sndx++]] << 18 | INV[arr[sndx++]] << 12
                    | INV[arr[sndx++]] << 6 | INV[arr[sndx++]];

            dest[d++] = (byte) (i >> 16);
            dest[d++] = (byte) (i >> 8);
            dest[d++] = (byte) i;

            if (sepCnt > 0 && ++cc == 19) {
                sndx += 2;
                cc = 0;
            }
        }

        if (d < len) {
            int i = 0;
            for (int j = 0; sndx <= endx - pad; j++) {
                i |= INV[arr[sndx++]] << (18 - j * 6);
            }
            for (int r = 16; d < len; r -= 8) {
                dest[d++] = (byte) (i >> r);
            }
        }

        return dest;
    }

    /**
     * Decodes a BASE64 encoded string.
     */
    public static byte[] decode(String s) {
        int length = s.length();
        if (length == 0) {
            return new byte[0];
        }

        int sndx = 0, endx = length - 1;
        int pad = s.charAt(endx) == '=' ? (s.charAt(endx - 1) == '=' ? 2
                : 1) : 0;
        int cnt = endx - sndx + 1;
        int sepCnt = length > 76 ? (s.charAt(76) == '\r' ? cnt / 78 : 0) << 1
                : 0;
        int len = ((cnt - sepCnt) * 6 >> 3) - pad;
        byte[] dest = new byte[len];

        int d = 0;
        for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
            int i = INV[s.charAt(sndx++)] << 18
                    | INV[s.charAt(sndx++)] << 12
                    | INV[s.charAt(sndx++)] << 6 | INV[s.charAt(sndx++)];

            dest[d++] = (byte) (i >> 16);
            dest[d++] = (byte) (i >> 8);
            dest[d++] = (byte) i;

            if (sepCnt > 0 && ++cc == 19) {
                sndx += 2;
                cc = 0;
            }
        }

        if (d < len) {
            int i = 0;
            for (int j = 0; sndx <= endx - pad; j++) {
                i |= INV[s.charAt(sndx++)] << (18 - j * 6);
            }
            for (int r = 16; d < len; r -= 8) {
                dest[d++] = (byte) (i >> r);
            }
        }

        return dest;
    }
}

Related

1. decoderBase64File(String base64Code, String type)
2. decode(String data, OutputStream out)
3. decode(Reader reader, OutputStream out)
4. decode(char c)
5. decode(String s, OutputStream os)
6. toString(String base64Encoded)
7. toBytes(String base64Encoded)
8. base64Decode(String property)
9. decode(String src)