com.young.security.utils.Base64 Maven / Gradle / Ivy
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package com.young.security.utils;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
* Base64字符串与字节码转换工具
*
* @author steven-pan
*
*/
public class Base64 {
private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
/**
* data[]进行编码
* @param data
* @return
*/
public static String encode(byte[] data) {
int start = 0;
int len = data.length;
StringBuffer buf = new StringBuffer(data.length * 3 / 2);
int end = len - 3;
int i = start;
int n = 0;
while (i <= end) {
int d = ((((int) data[i]) & 0x0ff) << 16)
| ((((int) data[i + 1]) & 0x0ff) << 8)
| (((int) data[i + 2]) & 0x0ff);
buf.append(legalChars[(d >> 18) & 63]);
buf.append(legalChars[(d >> 12) & 63]);
buf.append(legalChars[(d >> 6) & 63]);
buf.append(legalChars[d & 63]);
i += 3;
if (n++ >= 14) {
n = 0;
buf.append(" ");
}
}
if (i == start + len - 2) {
int d = ((((int) data[i]) & 0x0ff) << 16)
| ((((int) data[i + 1]) & 255) << 8);
buf.append(legalChars[(d >> 18) & 63]);
buf.append(legalChars[(d >> 12) & 63]);
buf.append(legalChars[(d >> 6) & 63]);
buf.append("=");
} else if (i == start + len - 1) {
int d = (((int) data[i]) & 0x0ff) << 16;
buf.append(legalChars[(d >> 18) & 63]);
buf.append(legalChars[(d >> 12) & 63]);
buf.append("==");
}
return buf.toString();
}
private static int decode(char c) {
if (c >= 'A' && c <= 'Z')
return ((int) c) - 65;
else if (c >= 'a' && c <= 'z')
return ((int) c) - 97 + 26;
else if (c >= '0' && c <= '9')
return ((int) c) - 48 + 26 + 26;
else
switch (c) {
case '+':
return 62;
case '/':
return 63;
case '=':
return 0;
default:
throw new RuntimeException("unexpected code: " + c);
}
}
/**
* Decodes the given Base64 encoded String to a new byte array. The byte
* array holding the decoded data is returned.
*/
public static byte[] decode(String s) {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
try {
decode(s, bos);
} catch (IOException e) {
throw new RuntimeException();
}
byte[] decodedBytes = bos.toByteArray();
try {
bos.close();
bos = null;
} catch (IOException ex) {
System.err.println("Error while decoding BASE64: " + ex.toString());
}
return decodedBytes;
}
private static void decode(String s, OutputStream os) throws IOException {
int i = 0;
int len = s.length();
while (true) {
while (i < len && s.charAt(i) <= ' ')
i++;
if (i == len)
break;
int tri = (decode(s.charAt(i)) << 18)
+ (decode(s.charAt(i + 1)) << 12)
+ (decode(s.charAt(i + 2)) << 6)
+ (decode(s.charAt(i + 3)));
os.write((tri >> 16) & 255);
if (s.charAt(i + 2) == '=')
break;
os.write((tri >> 8) & 255);
if (s.charAt(i + 3) == '=')
break;
os.write(tri & 255);
i += 4;
}
}
/**
* 去掉BASE64加密字符串换行符
*
* @param str
* @return
*/
public static String filter(String str) {
String output = "";
StringBuffer sb = new StringBuffer();
for (int i = 0; i < str.length(); i++) {
int asc = str.charAt(i);
if (asc != 10 && asc != 13) {
sb.append(str.subSequence(i, i + 1));
}
}
output = new String(sb);
return output;
}
// private static final char last2byte = (char) Integer
// .parseInt("00000011", 2);
//
// private static final char last4byte = (char) Integer
// .parseInt("00001111", 2);
//
// private static final char last6byte = (char) Integer
// .parseInt("00111111", 2);
//
// private static final char lead6byte = (char) Integer
// .parseInt("11111100", 2);
//
// private static final char lead4byte = (char) Integer
// .parseInt("11110000", 2);
//
// private static final char lead2byte = (char) Integer
// .parseInt("11000000", 2);
//
// private static final char[] encodeTable = new char[] { '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', '+', '/' };
//
//
// public static String encode(byte[] from) {
// StringBuffer to = new StringBuffer((int) (from.length * 1.34) + 3);
// int num = 0;
// char currentByte = 0;
// for (int i = 0; i < from.length; i++) {
// num = num % 8;
// while (num < 8) {
// switch (num) {
// case 0:
// currentByte = (char) (from[i] & lead6byte);
// currentByte = (char) (currentByte >>> 2);
// break;
// case 2:
// currentByte = (char) (from[i] & last6byte);
// break;
// case 4:
// currentByte = (char) (from[i] & last4byte);
// currentByte = (char) (currentByte << 2);
// if ((i + 1) < from.length) {
// currentByte |= (from[i + 1] & lead2byte) >>> 6;
// }
// break;
// case 6:
// currentByte = (char) (from[i] & last2byte);
// currentByte = (char) (currentByte << 4);
// if ((i + 1) < from.length) {
// currentByte |= (from[i + 1] & lead4byte) >>> 4;
// }
// break;
// }
// to.append(encodeTable[currentByte]);
// num += 6;
// }
// }
// if (to.length() % 4 != 0) {
// for (int i = 4 - to.length() % 4; i > 0; i--) {
// to.append("=");
// }
// }
// return to.toString();
// }
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