Description
Encodes a byte array into Base64 notation.
License
Apache License
Parameter
| Parameter | Description |
|---|
| source | The data to convert |
| off | Offset in array where conversion should begin |
| len | Length of data to convert |
Exception
| Parameter | Description |
|---|
| NullPointerException | if source array is null |
| IllegalArgumentException | if source array, offset, or length are invalid |
Return
The Base64-encoded data as a String
Declaration
public static String encodeBytes(byte[] source, int off, int len)
Method Source Code
//package com.java2s;
//License from project: Apache License
import java.io.UnsupportedEncodingException;
public class Main {
/** 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) '/' };
/**// www. j a v a 2 s . c om
* 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 uee) {
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;
}
/**
* <p>
* Encodes up to three bytes of the array <var>source</var> and writes the resulting four Base64 bytes to
* <var>destination</var>. The source and destination arrays can be manipulated anywhere along their length by specifying
* <var>srcOffset</var> and <var>destOffset</var>. This method does not check to make sure your arrays are large enough to
* accomodate <var>srcOffset</var> + 3 for the <var>source</var> array or <var>destOffset</var> + 4 for the
* <var>destination</var> array. The actual number of significant bytes in your array is given by <var>numSigBytes</var>.
* </p>
* <p>
* This is the lowest level of the encoding methods with all possible parameters.
* </p>
*
* @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 <var>destination</var> 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;
}
}
}
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