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// Licensed to the Apache Software Foundation (ASF) under one or more contributor
// license agreements. See the NOTICE.txt file distributed with this work for
// additional information regarding copyright ownership. The ASF licenses this
// file to you 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 org.apache.oodt.commons.util;
import java.io.*;
import org.apache.oodt.commons.io.*;
/** Base 64 encoding and decoding.
*
* This class provides methods for RFC-1521 specified "base 64" encoding and decoding of
* arbitrary data. Pass a byte array into the {@link #encode} method and you'll get a
* byte array result where all of the bytes are printable ASCII values. Pass that result
* into {@link #decode} and you'll get your original byte array.
*
* Sincere thanks to Tom Daley for providing a sample encoder algorithm and a great
* explanation of how RFC-1521 is supposed to work.
*
* @author Kelly
*/
public class Base64 {
/** Encode into base 64.
*
* Encode the given data into RFC-1521 base 64. Encoding a null array gives a
* null result.
*
* @param data The data to encode.
* @return Base-64 encoded data.
*/
public static byte[] encode(final byte[] data) {
return encode(data, 0, data.length);
}
/** Encode into base 64.
*
* Encode the given data into RFC-1521 base 64. Encoding a null array gives a
* null result. Start encoding at the given offset and go for the given amount of
* bytes.
*
* @param data The data to encode.
* @param offset Where to start looking for data to encode.
* @param length How much data to encode.
* @return Base-64 encoded data
*/
public static byte[] encode(final byte[] data, int offset, int length) {
if (data == null) return null;
if (offset < 0 || offset > data.length)
throw new IndexOutOfBoundsException("Can't encode at index " + offset + " which is beyond array bounds 0.."
+ data.length);
if (length < 0) throw new IllegalArgumentException("Can't encode a negative amount of data");
if (offset + length > data.length)
throw new IndexOutOfBoundsException("Can't encode beyond right edge of array");
int i, j;
byte dest[] = new byte[((length+2)/3)*4];
// Convert groups of 3 bytes into 4.
for (i = 0 + offset, j = 0; i < offset + length - 2; i += 3) {
dest[j++] = (byte) ((data[i] >>> 2) & 077);
dest[j++] = (byte) ((data[i+1] >>> 4) & 017 | (data[i] << 4) & 077);
dest[j++] = (byte) ((data[i+2] >>> 6) & 003 | (data[i+1] << 2) & 077);
dest[j++] = (byte) (data[i+2] & 077);
}
// Convert any leftover bytes.
if (i < offset + length) {
dest[j++] = (byte) ((data[i] >>> 2) & 077);
if (i < offset + length - 1) {
dest[j++] = (byte) ((data[i+1] >>> 4) & 017 | (data[i] << 4) & 077);
dest[j++] = (byte) ((data[i+1] << 2) & 077);
} else
dest[j++] = (byte) ((data[i] << 4) & 077);
}
// Now, map those onto base 64 printable ASCII.
for (i = 0; i data.length)
throw new IndexOutOfBoundsException("Can't decode beyond right edge of array");
// Ignore any padding at the end.
int tail = offset + length - 1;
while (tail >= offset && data[tail] == '=')
--tail;
byte dest[] = new byte[tail + offset + 1 - length/4];
// First, convert from base-64 ascii to 6 bit bytes.
for (int i = offset; i < offset+length; i++) {
if (data[i] == '=') data[i] = 0;
else if (data[i] == '/') data[i] = 63;
else if (data[i] == '+') data[i] = 62;
else if (data[i] >= '0' && data[i] <= '9')
data[i] = (byte)(data[i] - ('0' - 52));
else if (data[i] >= 'a' && data[i] <= 'z')
data[i] = (byte)(data[i] - ('a' - 26));
else if (data[i] >= 'A' && data[i] <= 'Z')
data[i] = (byte)(data[i] - 'A');
}
// Map those from 4 6-bit byte groups onto 3 8-bit byte groups.
int i, j;
for (i = 0 + offset, j = 0; j < dest.length - 2; i += 4, j += 3) {
dest[j] = (byte) (((data[i] << 2) & 255) | ((data[i+1] >>> 4) & 003));
dest[j+1] = (byte) (((data[i+1] << 4) & 255) | ((data[i+2] >>> 2) & 017));
dest[j+2] = (byte) (((data[i+2] << 6) & 255) | (data[i+3] & 077));
}
// And get the leftover ...
if (j < dest.length)
dest[j] = (byte) (((data[i] << 2) & 255) | ((data[i+1] >>> 4) & 003));
if (++j < dest.length)
dest[j] = (byte) (((data[i+1] << 4) & 255) | ((data[i+2] >>> 2) & 017));
// That's it.
return dest;
}
/** This class provides namespace for utility methods and shouldn't be instantiated.
*/
private Base64() {
throw new IllegalStateException(getClass().getName() + " should not be instantiated");
}
/** Command-line runner that encodes or decodes.
*
* @param argv Command-line arguments.
*/
public static void main(String[] argv) throws Exception {
if (argv.length < 1 || argv.length > 2) {
System.err.println("Usage: encode|decode [file]");
System.exit(1);
}
boolean encode = true;
if ("encode".equals(argv[0]))
encode = true;
else if ("decode".equals(argv[0]))
encode = false;
else {
System.err.println("Specify either \"encode\" or \"decode\"");
System.exit(1);
}
InputStream source = argv.length == 2? new BufferedInputStream(new FileInputStream(argv[1])) : System.in;
InputStream in;
OutputStream out;
if (encode) {
in = source;
out = new Base64EncodingOutputStream(System.out);
} else {
in = new Base64DecodingInputStream(source);
out = System.out;
}
byte[] buf = new byte[512];
int numRead;
while ((numRead = in.read(buf)) != -1)
out.write(buf, 0, numRead);
in.close();
out.close();
System.exit(0);
}
}