package com.github.hunter0x7c7.sync.utils;
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import java.io.BufferedInputStream;
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import java.io.ByteArrayOutputStream;
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import java.io.FileInputStream;
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import java.io.FilterOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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public class Base64Encoder extends FilterOutputStream {
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private static final char[] chars = {'A', 'B', 'C', 'D', 'E', 'F', 'G',
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'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
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'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
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'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
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'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6',
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'7', '8', '9', '+', '/'};
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private int charCount;
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private int carryOver;
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/***
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* Constructs a new Base64 encoder that writes output to the given
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* OutputStream.
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*
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* @param out
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* the output stream
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*/
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public Base64Encoder(OutputStream out) {
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super(out);
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}
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/***
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* Writes the given byte to the output stream in an encoded form.
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*
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* @exception IOException
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* if an I/O error occurs
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*/
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public void write(int b) throws IOException {
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// Take 24-bits from three octets, translate into four encoded chars
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// Break lines at 76 chars
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// If necessary, pad with 0 bits on the right at the end
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// Use = signs as padding at the end to ensure encodedLength % 4 == 0
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// Remove the sign bit,
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// thanks to Christian Schweingruber <chrigu@lorraine.ch>
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if (b < 0) {
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b += 256;
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}
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// First byte use first six bits, save last two bits
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if (charCount % 3 == 0) {
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int lookup = b >> 2;
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carryOver = b & 3; // last two bits
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out.write(chars[lookup]);
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}
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// Second byte use previous two bits and first four new bits,
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// save last four bits
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else if (charCount % 3 == 1) {
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int lookup = ((carryOver << 4) + (b >> 4)) & 63;
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carryOver = b & 15; // last four bits
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out.write(chars[lookup]);
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}
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// Third byte use previous four bits and first two new bits,
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// then use last six new bits
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else if (charCount % 3 == 2) {
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int lookup = ((carryOver << 2) + (b >> 6)) & 63;
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out.write(chars[lookup]);
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lookup = b & 63; // last six bits
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out.write(chars[lookup]);
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carryOver = 0;
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}
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charCount++;
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// Add newline every 76 output chars (that's 57 input chars)
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if (charCount % 57 == 0) {
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out.write('\n');
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}
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}
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/***
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* Writes the given byte array to the output stream in an encoded form.
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*
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* @param buf
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* the data to be written
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* @param off
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* the start offset of the data
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* @param len
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* the length of the data
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* @exception IOException
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* if an I/O error occurs
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*/
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public void write(byte[] buf, int off, int len) throws IOException {
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// This could of course be optimized
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for (int i = 0; i < len; i++) {
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write(buf[off + i]);
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}
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}
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/***
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* Closes the stream, this MUST be called to ensure proper padding is
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* written to the end of the output stream.
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*
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* @exception IOException
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* if an I/O error occurs
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*/
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public void close() throws IOException {
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// Handle leftover bytes
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if (charCount % 3 == 1) { // one leftover
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int lookup = (carryOver << 4) & 63;
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out.write(chars[lookup]);
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out.write('=');
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out.write('=');
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} else if (charCount % 3 == 2) { // two leftovers
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int lookup = (carryOver << 2) & 63;
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out.write(chars[lookup]);
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out.write('=');
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}
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super.close();
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}
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/***
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* Returns the encoded form of the given unencoded string. The encoder uses
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* the ISO-8859-1 (Latin-1) encoding to convert the string to bytes. For
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* greater control over the encoding, encode the string to bytes yourself
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* and use encode(byte[]).
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*
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* @param unencoded the string to encode
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* @return the encoded form of the unencoded string
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*/
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public static String encode(String unencoded) {
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try {
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byte[] bytes = unencoded.getBytes("UTF-8");
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return encode(bytes);
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} catch (Exception e) {
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e.printStackTrace();
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}
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return null;
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}
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/***
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* Returns the encoded form of the given unencoded string.
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*
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* @param bytes the bytes to encode
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* @return the encoded form of the unencoded string
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*/
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public static String encode(byte[] bytes) {
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if (bytes != null) {
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ByteArrayOutputStream out = new ByteArrayOutputStream((int) (bytes.length * 1.37));
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Base64Encoder encodedOut = new Base64Encoder(out);
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try {
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encodedOut.write(bytes);
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encodedOut.close();
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return out.toString("UTF-8");
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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return null;
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}
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public static void main(String[] args) throws Exception {
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if (args.length != 1) {
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System.err
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.println("Usage: java com.oreilly.servlet.Base64Encoder fileToEncode");
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return;
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}
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Base64Encoder encoder = null;
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BufferedInputStream in = null;
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try {
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encoder = new Base64Encoder(System.out);
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in = new BufferedInputStream(new FileInputStream(args[0]));
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byte[] buf = new byte[4 * 1024]; // 4K buffer
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int bytesRead;
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while ((bytesRead = in.read(buf)) != -1) {
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encoder.write(buf, 0, bytesRead);
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}
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} finally {
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if (in != null)
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in.close();
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if (encoder != null)
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encoder.close();
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}
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}
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}
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