package com.stylefeng.guns.modular.system.util.three;
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public class Base64Coder {
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public final static char[] base64_alphabet = new char[] { 'A', 'B', 'C',
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'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c',
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'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p',
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'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2',
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'3', '4', '5', '6', '7', '8', '9', '+', '/', '=' };
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public static String encode(byte[] data) {
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int length = data.length;
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byte[] char_array_3 = new byte[] { 0, 0, 0 };
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byte[] char_array_4 = new byte[] { '=', '=', '=', '=' };
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String retContent = "";
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int i = 0;
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int j = 0;
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int reversePos = 0;
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while (length > 0) {
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length--;
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char_array_3[i++] = data[reversePos++];
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if (i == 3) {
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char_array_4[0] = (byte) ((char_array_3[0] & 0xfc) >> 2); // convert
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// the
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// char
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char_array_4[1] = (byte) (((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4));
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char_array_4[2] = (byte) (((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6));
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char_array_4[3] = (byte) (char_array_3[2] & 0x3f);
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for (i = 0; (i < 4); i++)
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retContent += base64_alphabet[char_array_4[i]];
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i = 0;
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}
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}
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// handling the last input content
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if (i > 0) {
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for (j = i; j < 3; j++)
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char_array_3[j] = 0; // padding of zero
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char_array_4[0] = (byte) ((char_array_3[0] & 0xfc) >> 2); // right
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// shift
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char_array_4[1] = (byte) (((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4));
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char_array_4[2] = (byte) (((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6));
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char_array_4[3] = (byte) (char_array_3[2] & 0x3f);
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for (j = 0; (j < i + 1); j++)
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retContent += base64_alphabet[char_array_4[j]];
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while ((i++ < 3))
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// padding of '=' of output string
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retContent += '=';
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}
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return retContent;
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}
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public static String decode(String enContent) {
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byte[] data = enContent.getBytes();
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int i = 0, j = 0, enCode = 0;
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int mLength = data.length;
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byte[] char_array_4 = new byte[4];
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byte[] char_array_3 = new byte[3];
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String retContent = "";
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// filter out the padding '=' chars
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while (mLength > 0 && (((char) data[enCode]) != '=')
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&& isBase64((char) data[enCode])) {
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mLength--;
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char_array_4[i++] = data[enCode++];
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if (i == 4) {
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for (i = 0; i < 4; i++)
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char_array_4[i] = findChar((char) char_array_4[i]);
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char_array_3[0] = (byte) ((char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4));
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char_array_3[1] = (byte) (((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2));
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char_array_3[2] = (byte) (((char_array_4[2] & 0x3) << 6) + char_array_4[3]);
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for (i = 0; (i < 3); i++)
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retContent += (char) char_array_3[i];
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i = 0;
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}
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}
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// last content handling
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if (i > 0) {
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for (j = i; j < 4; j++)
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char_array_4[j] = 0;
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for (j = 0; j < 4; j++)
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char_array_4[j] = findChar((char) char_array_4[j]);
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char_array_3[0] = (byte) ((char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4));
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char_array_3[1] = (byte) (((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2));
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char_array_3[2] = (byte) (((char_array_4[2] & 0x3) << 6) + char_array_4[3]);
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for (j = 0; (j < i - 1); j++)
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retContent += (char) char_array_3[j];
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}
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return retContent;
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}
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public static boolean isBase64(char c) {
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boolean base64 = false;
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for (int i = 0; i < 64; i++) {
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if (c == base64_alphabet[i]) {
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base64 = true;
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break;
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}
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}
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return base64;
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}
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public static byte findChar(char x) {
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byte index = 64; // 65th char '='
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for (int i = 0; i < 64; i++) {
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if (x == base64_alphabet[i]) {
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index = (byte) i;
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break;
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}
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}
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return index;
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}
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}
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