package com.example.rsa_android;
/*
2 * Copyright (c) 1995, 2005, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
import java.io.InputStream;
import java.io.ByteArrayInputStream;
import java.io.OutputStream;
import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.io.IOException;
import java.nio.ByteBuffer;
/**
38 * This class defines the encoding half of character encoders.
39 * A character encoder is an algorithim for transforming 8 bit binary
40 * data into text (generally 7 bit ASCII or 8 bit ISO-Latin-1 text)
41 * for transmition over text channels such as e-mail and network news.
42 *
43 * The character encoders have been structured around a central theme
44 * that, in general, the encoded text has the form:
45 *
46 * <pre>
47 * [Buffer Prefix]
48 * [Line Prefix][encoded data atoms][Line Suffix]
49 * [Buffer Suffix]
50 * </pre>
51 *
52 * In the CharacterEncoder and CharacterDecoder classes, one complete
53 * chunk of data is referred to as a <i>buffer</i>. Encoded buffers
54 * are all text, and decoded buffers (sometimes just referred to as
55 * buffers) are binary octets.
56 *
57 * To create a custom encoder, you must, at a minimum, overide three
58 * abstract methods in this class.
59 * <DL>
60 * <DD>bytesPerAtom which tells the encoder how many bytes to
61 * send to encodeAtom
62 * <DD>encodeAtom which encodes the bytes sent to it as text.
63 * <DD>bytesPerLine which tells the encoder the maximum number of
64 * bytes per line.
65 * </DL>
66 *
67 * Several useful encoders have already been written and are
68 * referenced in the See Also list below.
69 *
70 * @author Chuck McManis
71 * @see CharacterDecoder;
72 * @see UCEncoder
73 * @see UUEncoder
74 * @see BASE64Encoder
75 */
public abstract class CharacterEncoder {
/** Stream that understands "printing" */
protected PrintStream pStream;
/** Return the number of bytes per atom of encoding */
abstract protected int bytesPerAtom();
/** Return the number of bytes that can be encoded per line */
abstract protected int bytesPerLine();
/**
* Encode the prefix for the entire buffer. By default is simply
* opens the PrintStream for use by the other functions.
*/
protected void encodeBufferPrefix(OutputStream aStream) throws IOException {
pStream = new PrintStream(aStream);
}
/**
* Encode the suffix for the entire buffer.
*/
protected void encodeBufferSuffix(OutputStream aStream) throws IOException {
}
/**
* Encode the prefix that starts every output line.
*/
protected void encodeLinePrefix(OutputStream aStream, int aLength)
throws IOException {
}
/**
* Encode the suffix that ends every output line. By default
* this method just prints a <newline> into the output stream.
*/
protected void encodeLineSuffix(OutputStream aStream) throws IOException {
pStream.println();
}
/** Encode one "atom" of information into characters. */
abstract protected void encodeAtom(OutputStream aStream, byte someBytes[],
int anOffset, int aLength) throws IOException;
/**
* This method works around the bizarre semantics of BufferedInputStream's
* read method.
*/
protected int readFully(InputStream in, byte buffer[])
throws java.io.IOException {
for (int i = 0; i < buffer.length; i++) {
int q = in.read();
if (q == -1)
return i;
buffer[i] = (byte)q;
}
return buffer.length;
}
/**
* Encode bytes from the input stream, and write them as text characters
* to the output stream. This method will run until it exhausts the
* input stream, but does not print the line suffix for a final
* line that is shorter than bytesPerLine().
*/
public void encode(InputStream inStream, OutputStream outStream)
throws IOException {
int j;
int numBytes;
byte tmpbuffer[] = new byte[bytesPerLine()];
encodeBufferPrefix(outStream);
while (true) {
numBytes = readFully(inStream, tmpbuffer);
if (numBytes == 0) {
break;
}
encodeLinePrefix(outStream, numBytes);
for (j = 0; j < numBytes; j += bytesPerAtom()) {
if ((j + bytesPerAtom()) <= numBytes) {
encodeAtom(outStream, tmpbuffer, j, bytesPerAtom());
} else {
encodeAtom(outStream, tmpbuffer, j, (numBytes)- j);
}
}
if (numBytes < bytesPerLine()) {
break;
} else {
encodeLineSuffix(outStream);
}
}
encodeBufferSuffix(outStream);
}
/**
* Encode the buffer in <i>aBuffer</i> and write the encoded
* result to the OutputStream <i>aStream</i>.
*/
public void encode(byte aBuffer[], OutputStream aStream)
throws IOException {
ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer);
encode(inStream, aStream);
}
/**
* A 'streamless' version of encode that simply takes a buffer of
* bytes and returns a string containing the encoded buffer.
*/
public String encode(byte aBuffer[]) {
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer);
String retVal = null;
try {
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