diff options
Diffstat (limited to 'simple/simple-common/src/main/java/org/simpleframework/common/encode/Base64Encoder.java')
| -rw-r--r-- | simple/simple-common/src/main/java/org/simpleframework/common/encode/Base64Encoder.java | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/simple/simple-common/src/main/java/org/simpleframework/common/encode/Base64Encoder.java b/simple/simple-common/src/main/java/org/simpleframework/common/encode/Base64Encoder.java new file mode 100644 index 0000000..54c820a --- /dev/null +++ b/simple/simple-common/src/main/java/org/simpleframework/common/encode/Base64Encoder.java @@ -0,0 +1,166 @@ +/* + * Base64Encoder.java February 2014 + * + * Copyright (C) 2014, Niall Gallagher <niallg@users.sf.net> + * + * 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 org.simpleframework.common.encode; + +/** + * The <code>Base64Encoder</code> is used to encode and decode base64 + * content. The implementation used here provides a reasonably fast + * memory efficient encoder for use with input and output streams. It + * is possible to achieve higher performance, however, ease of use + * and convenience are the priorities with this implementation. This + * can only decode complete blocks. + * + * @author Niall Gallagher + * + * @see org.simpleframework.common.encode.Base64OutputStream + * @see org.simpleframework.common.encode.Base64InputStream + */ +public class Base64Encoder { + + /** + * This maintains reference data used to fast decoding. + */ + private static final int[] REFERENCE = { + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62, 0, 0, 0, 63, + 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0, 0, 0, 0, + 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, + 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 0, + 0, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, + 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 0, 0, 0, 0, 0,}; + + /** + * This contains the base64 alphabet used for encoding. + */ + private static final char[] ALPHABET = { + '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', '+', '/', }; + + /** + * This method is used to encode the specified byte array of binary + * data in to base64 data. The block is complete and must be decoded + * as a complete block. + * + * @param buf this is the binary data to be encoded + * + * @return this is the base64 encoded value of the data + */ + public static char[] encode(byte[] buf) { + return encode(buf, 0, buf.length); + } + + /** + * This method is used to encode the specified byte array of binary + * data in to base64 data. The block is complete and must be decoded + * as a complete block. + * + * @param buf this is the binary data to be encoded + * @param off this is the offset to read the binary data from + * @param len this is the length of data to encode from the array + * + * @return this is the base64 encoded value of the data + */ + public static char[] encode(byte[] buf, int off, int len) { + char[] text = new char[((len + 2) / 3) * 4]; + int last = off + len; + int a = 0; + int i = 0; + + while (i < last) { + byte one = buf[i++]; + byte two = (i < len) ? buf[i++] : 0; + byte three = (i < len) ? buf[i++] : 0; + + int mask = 0x3F; + text[a++] = ALPHABET[(one >> 2) & mask]; + text[a++] = ALPHABET[((one << 4) | ((two & 0xFF) >> 4)) & mask]; + text[a++] = ALPHABET[((two << 2) | ((three & 0xFF) >> 6)) & mask]; + text[a++] = ALPHABET[three & mask]; + } + switch (len % 3) { + case 1: + text[--a] = '='; + case 2: + text[--a] = '='; + } + return text; + } + + /** + * This is used to decode the provide base64 data back in to an + * array of binary data. The data provided here must be a full block + * of base 64 data in order to be decoded. + * + * @param text this is the base64 text to be decoded + * + * @return this returns the resulting byte array + */ + public static byte[] decode(char[] text) { + return decode(text, 0, text.length); + } + + /** + * This is used to decode the provide base64 data back in to an + * array of binary data. The data provided here must be a full block + * of base 64 data in order to be decoded. + * + * @param text this is the base64 text to be decoded + * @param off this is the offset to read the text data from + * @param len this is the length of data to decode from the text + * + * @return this returns the resulting byte array + */ + public static byte[] decode(char[] text, int off, int len) { + int delta = 0; + + if (text[off + len - 1] == '=') { + delta = text[off + len - 2] == '=' ? 2 : 1; + } + byte[] buf = new byte[len * 3 / 4 - delta]; + int mask = 0xff; + int index = 0; + + for (int i = 0; i < len; i += 4) { + int pos = off + i; + int one = REFERENCE[text[pos]]; + int two = REFERENCE[text[pos + 1]]; + + buf[index++] = (byte) (((one << 2) | (two >> 4)) & mask); + + if (index >= buf.length) { + return buf; + } + int three = REFERENCE[text[pos + 2]]; + + buf[index++] = (byte) (((two << 4) | (three >> 2)) & mask); + + if (index >= buf.length) { + return buf; + } + int four = REFERENCE[text[pos + 3]]; + buf[index++] = (byte) (((three << 6) | four) & mask); + } + return buf; + } + +}
\ No newline at end of file |