package com.doumee.core.utils;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.io.UnsupportedEncodingException;
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import org.apache.commons.io.output.ByteArrayOutputStream;
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public class Base64Util {
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private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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.toCharArray();
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/**
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* @author: j
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* @date: 2014-8-21
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*
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* @param data
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* @return
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* @throws UnsupportedEncodingException
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*/
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public static byte[] Encode(byte[] data)
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throws UnsupportedEncodingException {
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int start = 0;
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int len = data.length;
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StringBuffer buf = new StringBuffer(data.length * 3 / 2);
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int end = len - 3;
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int i = start;
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int n = 0;
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while (i <= end) {
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int d = ((((int) data[i]) & 0x0ff) << 16)
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| ((((int) data[i + 1]) & 0x0ff) << 8)
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| (((int) data[i + 2]) & 0x0ff);
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buf.append(legalChars[(d >> 18) & 63]);
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buf.append(legalChars[(d >> 12) & 63]);
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buf.append(legalChars[(d >> 6) & 63]);
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buf.append(legalChars[d & 63]);
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i += 3;
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if (n++ >= 14) {
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n = 0;
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buf.append(" ");
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}
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}
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if (i == start + len - 2) {
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int d = ((((int) data[i]) & 0x0ff) << 16)
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| ((((int) data[i + 1]) & 255) << 8);
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buf.append(legalChars[(d >> 18) & 63]);
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buf.append(legalChars[(d >> 12) & 63]);
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buf.append(legalChars[(d >> 6) & 63]);
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buf.append("=");
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} else if (i == start + len - 1) {
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int d = (((int) data[i]) & 0x0ff) << 16;
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buf.append(legalChars[(d >> 18) & 63]);
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buf.append(legalChars[(d >> 12) & 63]);
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buf.append("==");
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}
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return buf.toString().getBytes("UTF-8");
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}
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public static byte[] decode(byte[] bytes) {
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String s = new String(bytes);
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ByteArrayOutputStream bos = new ByteArrayOutputStream();
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try {
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decode(s, bos);
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} catch (IOException e) {
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throw new RuntimeException();
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}
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byte[] decodedBytes = bos.toByteArray();
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try {
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bos.close();
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bos = null;
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} catch (IOException ex) {
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System.err.println("Error while decoding BASE64: " + ex.toString());
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}
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return decodedBytes;
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}
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private static void decode(String s, OutputStream os) throws IOException {
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int i = 0;
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int len = s.length();
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while (true) {
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while (i < len && s.charAt(i) <= ' ')
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i++;
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if (i == len)
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break;
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int tri = (decode(s.charAt(i)) << 18)
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+ (decode(s.charAt(i + 1)) << 12)
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+ (decode(s.charAt(i + 2)) << 6)
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+ (decode(s.charAt(i + 3)));
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os.write((tri >> 16) & 255);
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if (s.charAt(i + 2) == '=')
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break;
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os.write((tri >> 8) & 255);
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if (s.charAt(i + 3) == '=')
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break;
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os.write(tri & 255);
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i += 4;
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}
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}
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private static int decode(char c) {
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if (c >= 'A' && c <= 'Z')
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return ((int) c) - 65;
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else if (c >= 'a' && c <= 'z')
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return ((int) c) - 97 + 26;
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else if (c >= '0' && c <= '9')
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return ((int) c) - 48 + 26 + 26;
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else
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switch (c) {
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case '+':
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return 62;
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case '/':
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return 63;
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case '=':
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return 0;
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default:
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throw new RuntimeException("unexpected code: " + c);
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}
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}
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}
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