Here you can find the source of base64encode(byte[] data)
private static String base64encode(byte[] data)
//package com.java2s; /******************************************************************************* * Copyright (c) 2014 IBM Corporation and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * and Eclipse Distribution License v1.0 which accompany this distribution. * The Eclipse Public License is available at * http://www.eclipse.org/legal/epl-v10.html * and the Eclipse Distribution License is available at * http://www.eclipse.org/org/documents/edl-v10.php. * * Contributors:/*from www. j a v a 2 s . c o m*/ * Jochen Hiller *******************************************************************************/ public class Main { /** * Base64 Encode an array of bytes * * @see https://gist.github.com/EmilHernvall/953733 */ private static String base64encode(byte[] data) { char[] tbl = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' }; StringBuilder buffer = new StringBuilder(); int pad = 0; for (int i = 0; i < data.length; i += 3) { int b = ((data[i] & 0xFF) << 16) & 0xFFFFFF; if (i + 1 < data.length) { b |= (data[i + 1] & 0xFF) << 8; } else { pad++; } if (i + 2 < data.length) { b |= (data[i + 2] & 0xFF); } else { pad++; } for (int j = 0; j < 4 - pad; j++) { int c = (b & 0xFC0000) >> 18; buffer.append(tbl[c]); b <<= 6; } } for (int j = 0; j < pad; j++) { buffer.append("="); } return buffer.toString(); } }