blade.kit.Base64 Maven / Gradle / Ivy
/**
* Copyright (c) 2015, biezhi 王爵 ([email protected])
*
* 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 blade.kit;
import java.io.UnsupportedEncodingException;
/**
* BASE64工具类
*
* @author biezhi
* @since 1.0
*/
public class Base64 {
/** The equals sign (=) as a byte. */
private final static byte EQUALS_SIGN = (byte) '=';
/** Preferred encoding. */
private final static String PREFERRED_ENCODING = "US-ASCII";
/** The 64 valid Base64 values. */
private final static byte[] _STANDARD_ALPHABET = { (byte) 'A', (byte) 'B',
(byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H',
(byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N',
(byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T',
(byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z',
(byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f',
(byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l',
(byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r',
(byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x',
(byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3',
(byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9',
(byte) '+', (byte) '/' };
private static byte[] base64DecodeChars = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,
5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26,
27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1,
-1, -1, -1 };
/** Defeats instantiation. */
private Base64() {
}
/**
*
* Encodes up to three bytes of the array source and writes the
* resulting four Base64 bytes to destination. The source and
* destination arrays can be manipulated anywhere along their length by
* specifying srcOffset and destOffset. This method
* does not check to make sure your arrays are large enough to accomodate
* srcOffset + 3 for the source array or
* destOffset + 4 for the destination array. The
* actual number of significant bytes in your array is given by
* numSigBytes.
*
*
* This is the lowest level of the encoding methods with all possible
* parameters.
*
*
* @param source
* the array to convert
* @param srcOffset
* the index where conversion begins
* @param numSigBytes
* the number of significant bytes in your array
* @param destination
* the array to hold the conversion
* @param destOffset
* the index where output will be put
* @return the destination array
* @since 1.3
*/
private static byte[] encode3to4(byte[] source, int srcOffset,
int numSigBytes, byte[] destination, int destOffset) {
byte[] ALPHABET = _STANDARD_ALPHABET;
int inBuff = (numSigBytes > 0 ? ((source[srcOffset] << 24) >>> 8) : 0)
| (numSigBytes > 1 ? ((source[srcOffset + 1] << 24) >>> 16) : 0)
| (numSigBytes > 2 ? ((source[srcOffset + 2] << 24) >>> 24) : 0);
switch (numSigBytes) {
case 3:
destination[destOffset] = ALPHABET[(inBuff >>> 18)];
destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f];
destination[destOffset + 3] = ALPHABET[(inBuff) & 0x3f];
return destination;
case 2:
destination[destOffset] = ALPHABET[(inBuff >>> 18)];
destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f];
destination[destOffset + 3] = EQUALS_SIGN;
return destination;
case 1:
destination[destOffset] = ALPHABET[(inBuff >>> 18)];
destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
destination[destOffset + 2] = EQUALS_SIGN;
destination[destOffset + 3] = EQUALS_SIGN;
return destination;
default:
return destination;
}
}
/**
* Encode string as a byte array in Base64 annotation.
*
* @param string
* @return The Base64-encoded data as a string
*/
public static String encode(String string) {
byte[] bytes;
try {
bytes = string.getBytes(PREFERRED_ENCODING);
} catch (UnsupportedEncodingException e) {
bytes = string.getBytes();
}
return encodeBytes(bytes);
}
/**
* Encodes a byte array into Base64 notation.
*
* @param source
* The data to convert
* @return The Base64-encoded data as a String
* @throws NullPointerException
* if source array is null
* @throws IllegalArgumentException
* if source array, offset, or length are invalid
* @since 2.0
*/
public static String encodeBytes(byte[] source) {
return encodeBytes(source, 0, source.length);
}
/**
* Encodes a byte array into Base64 notation.
*
* @param source
* The data to convert
* @param off
* Offset in array where conversion should begin
* @param len
* Length of data to convert
* @return The Base64-encoded data as a String
* @throws NullPointerException
* if source array is null
* @throws IllegalArgumentException
* if source array, offset, or length are invalid
* @since 2.0
*/
public static String encodeBytes(byte[] source, int off, int len) {
byte[] encoded = encodeBytesToBytes(source, off, len);
try {
return new String(encoded, PREFERRED_ENCODING);
} catch (UnsupportedEncodingException uue) {
return new String(encoded);
}
}
/**
* Similar to {@link #encodeBytes(byte[], int, int)} but returns a byte
* array instead of instantiating a String. This is more efficient if you're
* working with I/O streams and have large data sets to encode.
*
*
* @param source
* The data to convert
* @param off
* Offset in array where conversion should begin
* @param len
* Length of data to convert
* @return The Base64-encoded data as a String if there is an error
* @throws NullPointerException
* if source array is null
* @throws IllegalArgumentException
* if source array, offset, or length are invalid
* @since 2.3.1
*/
public static byte[] encodeBytesToBytes(byte[] source, int off, int len) {
if (source == null)
throw new NullPointerException("Cannot serialize a null array.");
if (off < 0)
throw new IllegalArgumentException("Cannot have negative offset: "
+ off);
if (len < 0)
throw new IllegalArgumentException("Cannot have length offset: " + len);
if (off + len > source.length)
throw new IllegalArgumentException(
String
.format(
"Cannot have offset of %d and length of %d with array of length %d",
off, len, source.length));
// Bytes needed for actual encoding
int encLen = (len / 3) * 4 + (len % 3 > 0 ? 4 : 0);
byte[] outBuff = new byte[encLen];
int d = 0;
int e = 0;
int len2 = len - 2;
for (; d < len2; d += 3, e += 4)
encode3to4(source, d + off, 3, outBuff, e);
if (d < len) {
encode3to4(source, d + off, len - d, outBuff, e);
e += 4;
}
if (e <= outBuff.length - 1) {
byte[] finalOut = new byte[e];
System.arraycopy(outBuff, 0, finalOut, 0, e);
return finalOut;
} else
return outBuff;
}
//解码
public static byte[] decode(String str) throws UnsupportedEncodingException {
StringBuffer sb = new StringBuffer();
byte[] data = str.getBytes("US-ASCII");
int len = data.length;
int i = 0;
int b1, b2, b3, b4;
while (i < len) {
/* b1 */
do {
b1 = base64DecodeChars[data[i++]];
} while (i < len && b1 == -1);
if (b1 == -1)
break;
/* b2 */
do {
b2 = base64DecodeChars[data[i++]];
} while (i < len && b2 == -1);
if (b2 == -1)
break;
sb.append((char) ((b1 << 2) | ((b2 & 0X30) >>> 4)));
/* b3 */
do {
b3 = data[i++];
if (b3 == 61)
return sb.toString().getBytes("iso8859-1");
b3 = base64DecodeChars[b3];
} while (i < len && b3 == -1);
if (b3 == -1)
break;
sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));
/* b4 */
do {
b4 = data[i++];
if (b4 == 61)
return sb.toString().getBytes("iso8859-1");
b4 = base64DecodeChars[b4];
} while (i < len && b4 == -1);
if (b4 == -1)
break;
sb.append((char) (((b3 & 0X03) << 6) | b4));
}
return sb.toString().getBytes("iso8859-1");
}
public static String decoder(String str) throws UnsupportedEncodingException{
return new String(decode(str));
}
}© 2015 - 2025 Weber Informatics LLC | Privacy Policy