77 lines
2.3 KiB
Java
77 lines
2.3 KiB
Java
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package com.rarchives.ripme.utils;
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/**
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* Base64 encoder/decoder
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* From http://stackoverflow.com/a/4265472
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*
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*/
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public class Base64 {
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private final static char[] ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
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private static int[] toInt = new int[128];
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static {
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for(int i=0; i< ALPHABET.length; i++){
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toInt[ALPHABET[i]]= i;
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}
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}
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/**
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* Translates the specified byte array into Base64 string.
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*
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* @param buf the byte array (not null)
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* @return the translated Base64 string (not null)
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*/
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public static String encode(byte[] buf){
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int size = buf.length;
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char[] ar = new char[((size + 2) / 3) * 4];
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int a = 0;
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int i=0;
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while(i < size){
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byte b0 = buf[i++];
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byte b1 = (i < size) ? buf[i++] : 0;
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byte b2 = (i < size) ? buf[i++] : 0;
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int mask = 0x3F;
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ar[a++] = ALPHABET[(b0 >> 2) & mask];
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ar[a++] = ALPHABET[((b0 << 4) | ((b1 & 0xFF) >> 4)) & mask];
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ar[a++] = ALPHABET[((b1 << 2) | ((b2 & 0xFF) >> 6)) & mask];
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ar[a++] = ALPHABET[b2 & mask];
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}
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switch(size % 3){
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case 1: ar[--a] = '=';
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case 2: ar[--a] = '=';
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}
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return new String(ar);
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}
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/**
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* Translates the specified Base64 string into a byte array.
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*
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* @param s the Base64 string (not null)
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* @return the byte array (not null)
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*/
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public static byte[] decode(String s){
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int delta = s.endsWith( "==" ) ? 2 : s.endsWith( "=" ) ? 1 : 0;
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byte[] buffer = new byte[s.length()*3/4 - delta];
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int mask = 0xFF;
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int index = 0;
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for(int i=0; i< s.length(); i+=4){
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int c0 = toInt[s.charAt( i )];
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int c1 = toInt[s.charAt( i + 1)];
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buffer[index++]= (byte)(((c0 << 2) | (c1 >> 4)) & mask);
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if(index >= buffer.length){
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return buffer;
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}
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int c2 = toInt[s.charAt( i + 2)];
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buffer[index++]= (byte)(((c1 << 4) | (c2 >> 2)) & mask);
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if(index >= buffer.length){
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return buffer;
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}
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int c3 = toInt[s.charAt( i + 3 )];
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buffer[index++]= (byte)(((c2 << 6) | c3) & mask);
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}
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return buffer;
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}
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}
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