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The AIP SDK for Java provides Java APIs for all of AI APIs.
/*
* Copyright 2017 Baidu, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*/
package com.baidu.aip.util;
public class Base64Util {
private static final char[] ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
.toCharArray();
private static final char last2byte = (char) Integer
.parseInt("00000011", 2);
private static final char last4byte = (char) Integer
.parseInt("00001111", 2);
private static final char last6byte = (char) Integer
.parseInt("00111111", 2);
private static final char lead6byte = (char) Integer
.parseInt("11111100", 2);
private static final char lead4byte = (char) Integer
.parseInt("11110000", 2);
private static final char lead2byte = (char) Integer
.parseInt("11000000", 2);
private static final char[] encodeTable = new char[] { 'A', 'B', 'C', 'D',
'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q',
'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q',
'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3',
'4', '5', '6', '7', '8', '9', '+', '/' };
private static int[] toInt = new int[128];
static {
for (int i = 0; i < ALPHABET.length; i++) {
toInt[ALPHABET[i]] = i;
}
}
/**
* Base64 encoding.
*
* @param from
* The src data.
* @return cryto_str
*/
public static String encode(byte[] from) {
StringBuilder to = new StringBuilder((int) (from.length * 1.34) + 3);
int num = 0;
char currentByte = 0;
for (int i = 0; i < from.length; i++) {
num = num % 8;
while (num < 8) {
switch (num) {
case 0:
currentByte = (char) (from[i] & lead6byte);
currentByte = (char) (currentByte >>> 2);
break;
case 2:
currentByte = (char) (from[i] & last6byte);
break;
case 4:
currentByte = (char) (from[i] & last4byte);
currentByte = (char) (currentByte << 2);
if ((i + 1) < from.length) {
currentByte |= (from[i + 1] & lead2byte) >>> 6;
}
break;
case 6:
currentByte = (char) (from[i] & last2byte);
currentByte = (char) (currentByte << 4);
if ((i + 1) < from.length) {
currentByte |= (from[i + 1] & lead4byte) >>> 4;
}
break;
default:
break;
}
to.append(encodeTable[currentByte]);
num += 6;
}
}
if (to.length() % 4 != 0) {
for (int i = 4 - to.length() % 4; i > 0; i--) {
to.append("=");
}
}
return to.toString();
}
/**
* Translates the specified Base64 string into a byte array.
*
* @param s the Base64 string (not null)
* @return the byte array (not null)
*/
public static byte[] decode(String s) {
int delta = s.endsWith( "==" ) ? 2 : s.endsWith( "=" ) ? 1 : 0;
byte[] buffer = new byte[s.length() * 3 / 4 - delta];
int mask = 0xFF;
int index = 0;
for (int i = 0; i < s.length(); i += 4) {
int c0 = toInt[s.charAt( i )];
int c1 = toInt[s.charAt( i + 1)];
buffer[index++] = (byte)(((c0 << 2) | (c1 >> 4)) & mask);
if (index >= buffer.length) {
return buffer;
}
int c2 = toInt[s.charAt( i + 2)];
buffer[index++] = (byte)(((c1 << 4) | (c2 >> 2)) & mask);
if (index >= buffer.length) {
return buffer;
}
int c3 = toInt[s.charAt( i + 3 )];
buffer[index++] = (byte)(((c2 << 6) | c3) & mask);
}
return buffer;
}
}