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java base 16 编码和解码
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| /*** | |
| * Copyright 2006 bsmith@qq.com | |
| * | |
| * Licensed 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 cn.is.ftp; | |
| import java.io.UnsupportedEncodingException; | |
| /** | |
| * base 16 hex encoding. | |
| * | |
| * @author bsmith.zhao | |
| * @date 2006-05-16 11:22:12 | |
| */ | |
| public class Base16 { | |
| /** | |
| * the example. | |
| * | |
| * @param args | |
| * @throws UnsupportedEncodingException | |
| */ | |
| public static void main(String args[]) throws UnsupportedEncodingException { | |
| String str = "0123456abcdef中文123abc"; | |
| // byte[] data = str.getBytes("UTF-8"); | |
| byte[] data = str.getBytes("UTF-8"); | |
| String hex = encode(data, 0, data.length); | |
| System.out.println(hex); | |
| data = decode(hex); | |
| str = new String(data, "UTF-8"); | |
| System.out.println(str); | |
| hex += "a"; | |
| data = decode(hex); | |
| str = new String(data, "UTF-8"); | |
| System.out.println(str); | |
| } | |
| // encoding characters table. | |
| public static final char[] ENC_TAB = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; | |
| // decoding characters table. | |
| public static final byte[] DEC_TAB = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 16 | |
| 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 32 | |
| 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 48 | |
| 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 64 | |
| 0x00, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 80 | |
| 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 96 | |
| 0x00, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 112 | |
| 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; | |
| /** | |
| * encode byte array data to base 16 hex string. | |
| * | |
| * @param data byte array data. | |
| * @return base 16 hex string. | |
| */ | |
| public static String encode(byte[] data) { | |
| return encode(data, 0, data.length); | |
| } | |
| /** | |
| * encode byte array data from offset to offset+length to base 16 hex string. | |
| * | |
| * @param data byte array data. | |
| * @param offset start index, included. | |
| * @param length total encode length. | |
| * @return the base 16 hex string. | |
| */ | |
| public static String encode(byte[] data, int offset, int length) { | |
| StringBuffer buff = new StringBuffer(length * 2); | |
| int i = offset, total = offset + length; | |
| while (i < total) { | |
| buff.append(ENC_TAB[(data[i] & 0xF0) >> 4]); | |
| buff.append(ENC_TAB[data[i] & 0x0F]); | |
| i++; | |
| } | |
| return buff.toString(); | |
| } | |
| /** | |
| * decode base 16 hex string to byte array. | |
| * | |
| * @param hex base 16 hex string. | |
| * @return byte array data. | |
| */ | |
| public static byte[] decode(String hex) { | |
| byte[] data = new byte[hex.length() / 2]; | |
| decode(hex, data, 0); | |
| return data; | |
| } | |
| /** | |
| * decode base 16 hex string to byte array. | |
| * | |
| * @param hex base 16 hex string. | |
| * @param data byte array data. | |
| * @param offset byte array data start index, included. | |
| */ | |
| public static void decode(String hex, byte[] data, int offset) { | |
| int i = 0, total = (hex.length() / 2) * 2, idx = offset; | |
| while (i < total) { | |
| data[idx++] = (byte) ((DEC_TAB[hex.charAt(i++)] << 4) | DEC_TAB[hex.charAt(i++)]); | |
| } | |
| } | |
| } |
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| /*** | |
| * Copyright 2006 bsmith@qq.com | |
| * | |
| * Licensed 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 cn.is.ftp; | |
| import java.io.UnsupportedEncodingException; | |
| import java.net.URLEncoder; | |
| /** | |
| * base 64 hex string encoding. | |
| * | |
| * @date 2006-05-16 11:22:12 | |
| */ | |
| public class Base64 { | |
| /** | |
| * the example. | |
| * | |
| * @param args | |
| * @throws UnsupportedEncodingException | |
| */ | |
| public static void main(String[] args) throws UnsupportedEncodingException { | |
| String data = "0123456abcdef中文123abc"; | |
| byte[] result = Base64.encode(data.getBytes()); | |
| String str = "+/\n\r"; | |
| System.out.println(URLEncoder.encode(str, "UTF-8")); | |
| System.out.println(data); | |
| System.out.println(new String(result)); | |
| System.out.println(new String(Base64.decode(new String(result)))); | |
| } | |
| /** | |
| * encode characters table. | |
| */ | |
| private static final byte[] ENC_TAB = { (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) '/' }; | |
| /** | |
| * decode characters table. | |
| */ | |
| private static final byte[] DEC_TAB; | |
| static { | |
| DEC_TAB = new byte[128]; | |
| for (int i = 0; i < 128; i++) { | |
| DEC_TAB[i] = (byte) -1; | |
| } | |
| for (int i = 'A'; i <= 'Z'; i++) { | |
| DEC_TAB[i] = (byte) (i - 'A'); | |
| } | |
| for (int i = 'a'; i <= 'z'; i++) { | |
| DEC_TAB[i] = (byte) (i - 'a' + 26); | |
| } | |
| for (int i = '0'; i <= '9'; i++) { | |
| DEC_TAB[i] = (byte) (i - '0' + 52); | |
| } | |
| DEC_TAB['+'] = 62; | |
| DEC_TAB['/'] = 63; | |
| } | |
| /** | |
| * encode byte array data to base 64 hex string data. | |
| * | |
| * @param data byte array data. | |
| * @return base 64 hex string data. use new String("UTF-8") to get the String format. | |
| */ | |
| public static byte[] encode(byte[] data) { | |
| byte[] bytes; | |
| int modulus = data.length % 3; | |
| if (modulus == 0) { | |
| bytes = new byte[(4 * data.length) / 3]; | |
| } else { | |
| bytes = new byte[4 * ((data.length / 3) + 1)]; | |
| } | |
| int dataLength = (data.length - modulus); | |
| int a1; | |
| int a2; | |
| int a3; | |
| for (int i = 0, j = 0; i < dataLength; i += 3, j += 4) { | |
| a1 = data[i] & 0xff; | |
| a2 = data[i + 1] & 0xff; | |
| a3 = data[i + 2] & 0xff; | |
| bytes[j] = ENC_TAB[(a1 >>> 2) & 0x3f]; | |
| bytes[j + 1] = ENC_TAB[((a1 << 4) | (a2 >>> 4)) & 0x3f]; | |
| bytes[j + 2] = ENC_TAB[((a2 << 2) | (a3 >>> 6)) & 0x3f]; | |
| bytes[j + 3] = ENC_TAB[a3 & 0x3f]; | |
| } | |
| int b1; | |
| int b2; | |
| int b3; | |
| int d1; | |
| int d2; | |
| switch (modulus) { | |
| case 0: /* nothing left to do */ | |
| break; | |
| case 1: | |
| d1 = data[data.length - 1] & 0xff; | |
| b1 = (d1 >>> 2) & 0x3f; | |
| b2 = (d1 << 4) & 0x3f; | |
| bytes[bytes.length - 4] = ENC_TAB[b1]; | |
| bytes[bytes.length - 3] = ENC_TAB[b2]; | |
| bytes[bytes.length - 2] = (byte) '='; | |
| bytes[bytes.length - 1] = (byte) '='; | |
| break; | |
| case 2: | |
| d1 = data[data.length - 2] & 0xff; | |
| d2 = data[data.length - 1] & 0xff; | |
| b1 = (d1 >>> 2) & 0x3f; | |
| b2 = ((d1 << 4) | (d2 >>> 4)) & 0x3f; | |
| b3 = (d2 << 2) & 0x3f; | |
| bytes[bytes.length - 4] = ENC_TAB[b1]; | |
| bytes[bytes.length - 3] = ENC_TAB[b2]; | |
| bytes[bytes.length - 2] = ENC_TAB[b3]; | |
| bytes[bytes.length - 1] = (byte) '='; | |
| break; | |
| } | |
| return bytes; | |
| } | |
| /** | |
| * decode base 64 string data to byte data array. | |
| * | |
| * @param data base 64 string data. | |
| * @return byte data array. | |
| */ | |
| public static byte[] decode(byte[] data) { | |
| byte[] bytes; | |
| byte b1; | |
| byte b2; | |
| byte b3; | |
| byte b4; | |
| data = discardNonBase64Bytes(data); | |
| if (data[data.length - 2] == '=') { | |
| bytes = new byte[(((data.length / 4) - 1) * 3) + 1]; | |
| } else if (data[data.length - 1] == '=') { | |
| bytes = new byte[(((data.length / 4) - 1) * 3) + 2]; | |
| } else { | |
| bytes = new byte[((data.length / 4) * 3)]; | |
| } | |
| for (int i = 0, j = 0; i < (data.length - 4); i += 4, j += 3) { | |
| b1 = DEC_TAB[data[i]]; | |
| b2 = DEC_TAB[data[i + 1]]; | |
| b3 = DEC_TAB[data[i + 2]]; | |
| b4 = DEC_TAB[data[i + 3]]; | |
| bytes[j] = (byte) ((b1 << 2) | (b2 >> 4)); | |
| bytes[j + 1] = (byte) ((b2 << 4) | (b3 >> 2)); | |
| bytes[j + 2] = (byte) ((b3 << 6) | b4); | |
| } | |
| if (data[data.length - 2] == '=') { | |
| b1 = DEC_TAB[data[data.length - 4]]; | |
| b2 = DEC_TAB[data[data.length - 3]]; | |
| bytes[bytes.length - 1] = (byte) ((b1 << 2) | (b2 >> 4)); | |
| } else if (data[data.length - 1] == '=') { | |
| b1 = DEC_TAB[data[data.length - 4]]; | |
| b2 = DEC_TAB[data[data.length - 3]]; | |
| b3 = DEC_TAB[data[data.length - 2]]; | |
| bytes[bytes.length - 2] = (byte) ((b1 << 2) | (b2 >> 4)); | |
| bytes[bytes.length - 1] = (byte) ((b2 << 4) | (b3 >> 2)); | |
| } else { | |
| b1 = DEC_TAB[data[data.length - 4]]; | |
| b2 = DEC_TAB[data[data.length - 3]]; | |
| b3 = DEC_TAB[data[data.length - 2]]; | |
| b4 = DEC_TAB[data[data.length - 1]]; | |
| bytes[bytes.length - 3] = (byte) ((b1 << 2) | (b2 >> 4)); | |
| bytes[bytes.length - 2] = (byte) ((b2 << 4) | (b3 >> 2)); | |
| bytes[bytes.length - 1] = (byte) ((b3 << 6) | b4); | |
| } | |
| return bytes; | |
| } | |
| /** | |
| * decode base 64 string to byte array data. | |
| * | |
| * @param data base 64 string. | |
| * @return byte array data. | |
| */ | |
| public static byte[] decode(String data) { | |
| byte[] bytes; | |
| byte b1; | |
| byte b2; | |
| byte b3; | |
| byte b4; | |
| data = discardNonBase64Chars(data); | |
| if (data.charAt(data.length() - 2) == '=') { | |
| bytes = new byte[(((data.length() / 4) - 1) * 3) + 1]; | |
| } else if (data.charAt(data.length() - 1) == '=') { | |
| bytes = new byte[(((data.length() / 4) - 1) * 3) + 2]; | |
| } else { | |
| bytes = new byte[((data.length() / 4) * 3)]; | |
| } | |
| for (int i = 0, j = 0; i < (data.length() - 4); i += 4, j += 3) { | |
| b1 = DEC_TAB[data.charAt(i)]; | |
| b2 = DEC_TAB[data.charAt(i + 1)]; | |
| b3 = DEC_TAB[data.charAt(i + 2)]; | |
| b4 = DEC_TAB[data.charAt(i + 3)]; | |
| bytes[j] = (byte) ((b1 << 2) | (b2 >> 4)); | |
| bytes[j + 1] = (byte) ((b2 << 4) | (b3 >> 2)); | |
| bytes[j + 2] = (byte) ((b3 << 6) | b4); | |
| } | |
| if (data.charAt(data.length() - 2) == '=') { | |
| b1 = DEC_TAB[data.charAt(data.length() - 4)]; | |
| b2 = DEC_TAB[data.charAt(data.length() - 3)]; | |
| bytes[bytes.length - 1] = (byte) ((b1 << 2) | (b2 >> 4)); | |
| } else if (data.charAt(data.length() - 1) == '=') { | |
| b1 = DEC_TAB[data.charAt(data.length() - 4)]; | |
| b2 = DEC_TAB[data.charAt(data.length() - 3)]; | |
| b3 = DEC_TAB[data.charAt(data.length() - 2)]; | |
| bytes[bytes.length - 2] = (byte) ((b1 << 2) | (b2 >> 4)); | |
| bytes[bytes.length - 1] = (byte) ((b2 << 4) | (b3 >> 2)); | |
| } else { | |
| b1 = DEC_TAB[data.charAt(data.length() - 4)]; | |
| b2 = DEC_TAB[data.charAt(data.length() - 3)]; | |
| b3 = DEC_TAB[data.charAt(data.length() - 2)]; | |
| b4 = DEC_TAB[data.charAt(data.length() - 1)]; | |
| bytes[bytes.length - 3] = (byte) ((b1 << 2) | (b2 >> 4)); | |
| bytes[bytes.length - 2] = (byte) ((b2 << 4) | (b3 >> 2)); | |
| bytes[bytes.length - 1] = (byte) ((b3 << 6) | b4); | |
| } | |
| return bytes; | |
| } | |
| private static byte[] discardNonBase64Bytes(byte[] data) { | |
| byte[] temp = new byte[data.length]; | |
| int bytesCopied = 0; | |
| for (int i = 0; i < data.length; i++) { | |
| if (isValidBase64Byte(data[i])) { | |
| temp[bytesCopied++] = data[i]; | |
| } | |
| } | |
| byte[] newData = new byte[bytesCopied]; | |
| System.arraycopy(temp, 0, newData, 0, bytesCopied); | |
| return newData; | |
| } | |
| private static String discardNonBase64Chars(String data) { | |
| StringBuffer sb = new StringBuffer(); | |
| int length = data.length(); | |
| for (int i = 0; i < length; i++) { | |
| if (isValidBase64Byte((byte) (data.charAt(i)))) { | |
| sb.append(data.charAt(i)); | |
| } | |
| } | |
| return sb.toString(); | |
| } | |
| private static boolean isValidBase64Byte(byte b) { | |
| if (b == '=') { | |
| return true; | |
| } else if ((b < 0) || (b >= 128)) { | |
| return false; | |
| } else if (DEC_TAB[b] == -1) { | |
| return false; | |
| } | |
| return true; | |
| } | |
| } |
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