111 lines
3.5 KiB
Java
111 lines
3.5 KiB
Java
import java.io.ByteArrayOutputStream;
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import java.util.Random;
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import java.util.Arrays;
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import javax.xml.bind.DatatypeConverter;
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public class Base64
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{
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public static String encode(String text)
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{
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byte[] data = text.getBytes();
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return encode(data);
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}
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public static String encode(byte[] data) {
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char[] tbl = {
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'A','B','C','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','d','e','f',
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'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v',
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'w','x','y','z','0','1','2','3','4','5','6','7','8','9','+','/' };
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StringBuilder buffer = new StringBuilder();
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int pad = 0;
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for (int i = 0; i < data.length; i += 3) {
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int b = ((data[i] & 0xFF) << 16) & 0xFFFFFF;
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if (i + 1 < data.length) {
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b |= (data[i+1] & 0xFF) << 8;
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} else {
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pad++;
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}
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if (i + 2 < data.length) {
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b |= (data[i+2] & 0xFF);
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} else {
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pad++;
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}
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for (int j = 0; j < 4 - pad; j++) {
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int c = (b & 0xFC0000) >> 18;
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buffer.append(tbl[c]);
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b <<= 6;
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}
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}
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for (int j = 0; j < pad; j++) {
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buffer.append("=");
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}
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return buffer.toString();
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}
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public static String decodeStr(String data)
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{
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return new String(decode(data));
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}
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public static byte[] decode(String data)
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{
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int[] tbl = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54,
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55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2,
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3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
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20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30,
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31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
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48, 49, 50, 51, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 };
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byte[] bytes = data.getBytes();
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ByteArrayOutputStream buffer = new ByteArrayOutputStream();
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for (int i = 0; i < bytes.length; ) {
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int b = 0;
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if (tbl[bytes[i]] != -1) {
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b = (tbl[bytes[i]] & 0xFF) << 18;
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}
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// skip unknown characters
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else {
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i++;
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continue;
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}
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int num = 0;
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if (i + 1 < bytes.length && tbl[bytes[i+1]] != -1) {
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b = b | ((tbl[bytes[i+1]] & 0xFF) << 12);
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num++;
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}
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if (i + 2 < bytes.length && tbl[bytes[i+2]] != -1) {
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b = b | ((tbl[bytes[i+2]] & 0xFF) << 6);
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num++;
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}
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if (i + 3 < bytes.length && tbl[bytes[i+3]] != -1) {
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b = b | (tbl[bytes[i+3]] & 0xFF);
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num++;
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}
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while (num > 0) {
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int c = (b & 0xFF0000) >> 16;
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buffer.write((char)c);
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b <<= 8;
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num--;
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}
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i += 4;
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}
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return buffer.toByteArray();
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}
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}
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