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jp.sf.amateras.mirage.util.Base64Util Maven / Gradle / Ivy
/*
* Copyright 2004-2010 the Seasar Foundation and the Others.
*
* 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 jp.sf.amateras.mirage.util;
/**
* Base64を扱うためのユーティリティクラスです。
*
* @author higa
*
*/
public class Base64Util {
private static final char[] ENCODE_TABLE = { '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 final char PAD = '=';
private static final byte[] DECODE_TABLE = new byte[128];
static {
for (int i = 0; i < DECODE_TABLE.length; i++) {
DECODE_TABLE[i] = Byte.MAX_VALUE;
}
for (int i = 0; i < ENCODE_TABLE.length; i++) {
DECODE_TABLE[ENCODE_TABLE[i]] = (byte) i;
}
}
/**
* Base64でエンコードします。
*
* @param inData
* @return エンコードされたデータ
*/
public static String encode(final byte[] inData) {
if (inData == null || inData.length == 0) {
return "";
}
int mod = inData.length % 3;
int num = inData.length / 3;
char[] outData = null;
if (mod != 0) {
outData = new char[(num + 1) * 4];
} else {
outData = new char[num * 4];
}
for (int i = 0; i < num; i++) {
encode(inData, i * 3, outData, i * 4);
}
switch (mod) {
case 1:
encode2pad(inData, num * 3, outData, num * 4);
break;
case 2:
encode1pad(inData, num * 3, outData, num * 4);
break;
}
return new String(outData);
}
/**
* Base64でエンコードされたデータをデコードします。
*
* @param inData
* @return デコードされたデータ
*/
public static byte[] decode(final String inData) {
int num = (inData.length() / 4) - 1;
int lastBytes = getLastBytes(inData);
byte[] outData = new byte[num * 3 + lastBytes];
for (int i = 0; i < num; i++) {
decode(inData, i * 4, outData, i * 3);
}
switch (lastBytes) {
case 1:
decode1byte(inData, num * 4, outData, num * 3);
break;
case 2:
decode2byte(inData, num * 4, outData, num * 3);
break;
default:
decode(inData, num * 4, outData, num * 3);
}
return outData;
}
private static void encode(final byte[] inData, final int inIndex,
final char[] outData, final int outIndex) {
int i = ((inData[inIndex] & 0xff) << 16)
+ ((inData[inIndex + 1] & 0xff) << 8)
+ (inData[inIndex + 2] & 0xff);
outData[outIndex] = ENCODE_TABLE[i >> 18];
outData[outIndex + 1] = ENCODE_TABLE[(i >> 12) & 0x3f];
outData[outIndex + 2] = ENCODE_TABLE[(i >> 6) & 0x3f];
outData[outIndex + 3] = ENCODE_TABLE[i & 0x3f];
}
private static void encode2pad(final byte[] inData, final int inIndex,
final char[] outData, final int outIndex) {
int i = inData[inIndex] & 0xff;
outData[outIndex] = ENCODE_TABLE[i >> 2];
outData[outIndex + 1] = ENCODE_TABLE[(i << 4) & 0x3f];
outData[outIndex + 2] = PAD;
outData[outIndex + 3] = PAD;
}
private static void encode1pad(final byte[] inData, final int inIndex,
final char[] outData, final int outIndex) {
int i = ((inData[inIndex] & 0xff) << 8) + (inData[inIndex + 1] & 0xff);
outData[outIndex] = ENCODE_TABLE[i >> 10];
outData[outIndex + 1] = ENCODE_TABLE[(i >> 4) & 0x3f];
outData[outIndex + 2] = ENCODE_TABLE[(i << 2) & 0x3f];
outData[outIndex + 3] = PAD;
}
private static void decode(final String inData, final int inIndex,
final byte[] outData, final int outIndex) {
byte b0 = DECODE_TABLE[inData.charAt(inIndex)];
byte b1 = DECODE_TABLE[inData.charAt(inIndex + 1)];
byte b2 = DECODE_TABLE[inData.charAt(inIndex + 2)];
byte b3 = DECODE_TABLE[inData.charAt(inIndex + 3)];
outData[outIndex] = (byte) (b0 << 2 & 0xfc | b1 >> 4 & 0x3);
outData[outIndex + 1] = (byte) (b1 << 4 & 0xf0 | b2 >> 2 & 0xf);
outData[outIndex + 2] = (byte) (b2 << 6 & 0xc0 | b3 & 0x3f);
}
private static void decode1byte(final String inData, final int inIndex,
final byte[] outData, final int outIndex) {
byte b0 = DECODE_TABLE[inData.charAt(inIndex)];
byte b1 = DECODE_TABLE[inData.charAt(inIndex + 1)];
outData[outIndex] = (byte) (b0 << 2 & 0xfc | b1 >> 4 & 0x3);
}
private static void decode2byte(final String inData, final int inIndex,
final byte[] outData, final int outIndex) {
byte b0 = DECODE_TABLE[inData.charAt(inIndex)];
byte b1 = DECODE_TABLE[inData.charAt(inIndex + 1)];
byte b2 = DECODE_TABLE[inData.charAt(inIndex + 2)];
outData[outIndex] = (byte) (b0 << 2 & 0xfc | b1 >> 4 & 0x3);
outData[outIndex + 1] = (byte) (b1 << 4 & 0xf0 | b2 >> 2 & 0xf);
}
private static int getLastBytes(final String inData) {
int len = inData.length();
if (inData.charAt(len - 2) == PAD) {
return 1;
} else if (inData.charAt(len - 1) == PAD) {
return 2;
} else {
return 3;
}
}
}
