Javascript base64加密和解密函數(shù)，增加了對(duì)中文的處理：
var BASE64={
utf16to8: function(str)
{
var out, i, len, c;
out = "";
len = str.length;
for(i = 0; i < len; i++)
{
c = str.charCodeAt(i);
if ((c >= 0x0001) && (c <= 0x007F))
{
out += str.charAt(i);
}
else if (c > 0x07FF)
{
out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
}
else
{
out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
}
}
return out;
},
utf8to16: function(str)
{
var out, i, len, c;
var char2, char3;
out = "";
len = str.length;
i = 0;
while(i < len)
{
c = str.charCodeAt(i++);
switch(c >> 4)
{
case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
// 0xxxxxxx
out += str.charAt(i-1);
break;
case 12: case 13:
// 110x xxxx 10xx xxxx
char2 = str.charCodeAt(i++);
out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
break;
case 14:
// 1110 xxxx 10xx xxxx 10xx xxxx
char2 = str.charCodeAt(i++);
char3 = str.charCodeAt(i++);
out += String.fromCharCode(((c & 0x0F) << 12) |
((char2 & 0x3F) << 6) |
((char3 & 0x3F) << 0));
break;
}
}
return out;
},
/**
* 此變量為編碼的key，每個(gè)字符的下標(biāo)相對(duì)應(yīng)于它所代表的編碼。
*/
enKey: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/',
/**
* 此變量為解碼的key，是一個(gè)數(shù)組，BASE64的字符的ASCII值做下標(biāo)，所對(duì)應(yīng)的就是該字符所代表的編碼值。
*/
deKey: new Array(
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
-1, 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, -1, -1, -1, -1, -1,
-1, 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, -1, -1, -1, -1, -1
),
/**
* 編碼
*/
encode: function(src)
{
src=this.utf16to8(src);
//用一個(gè)數(shù)組來存放編碼后的字符，效率比用字符串相加高很多。
var str=new Array();
var ch1, ch2, ch3;
var pos=0;
//每三個(gè)字符進(jìn)行編碼。
while(pos+3<=src.length)
{
ch1=src.charCodeAt(pos++);
ch2=src.charCodeAt(pos++);
ch3=src.charCodeAt(pos++);
str.push(this.enKey.charAt(ch1>>2), this.enKey.charAt(((ch1<<4)+(ch2>>4))&0x3f));
str.push(this.enKey.charAt(((ch2<<2)+(ch3>>6))&0x3f), this.enKey.charAt(ch3&0x3f));
}
//給剩下的字符進(jìn)行編碼。
if(pos<src.length)
{
ch1=src.charCodeAt(pos++);
str.push(this.enKey.charAt(ch1>>2));
if(pos<src.length)
{
ch2=src.charCodeAt(pos);
str.push(this.enKey.charAt(((ch1<<4)+(ch2>>4))&0x3f));
str.push(this.enKey.charAt(ch2<<2&0x3f), '=');
}
else
{
str.push(this.enKey.charAt(ch1<<4&0x3f), '==');
}
}
//組合各編碼后的字符，連成一個(gè)字符串。
return str.join('');
},
/**
* 解碼。
*/
decode: function(src)
{
//用一個(gè)數(shù)組來存放解碼后的字符。
var str=new Array();
var ch1, ch2, ch3, ch4;
var pos=0;
//過濾非法字符，并去掉'='。
src=src.replace(/[^A-Za-z0-9\+\/]/g, '');
//decode the source string in partition of per four characters.
while(pos+4<=src.length)
{
ch1=this.deKey[src.charCodeAt(pos++)];
ch2=this.deKey[src.charCodeAt(pos++)];
ch3=this.deKey[src.charCodeAt(pos++)];
ch4=this.deKey[src.charCodeAt(pos++)];
str.push(String.fromCharCode(
(ch1<<2&0xff)+(ch2>>4), (ch2<<4&0xff)+(ch3>>2), (ch3<<6&0xff)+ch4));
}
//給剩下的字符進(jìn)行解碼。
if(pos+1<src.length)
{
ch1=this.deKey[src.charCodeAt(pos++)];
ch2=this.deKey[src.charCodeAt(pos++)];
if(pos<src.length)
{
ch3=this.deKey[src.charCodeAt(pos)];
str.push(String.fromCharCode((ch1<<2&0xff)+(ch2>>4), (ch2<<4&0xff)+(ch3>>2)));
}
else
{
str.push(String.fromCharCode((ch1<<2&0xff)+(ch2>>4)));
}
}
//組合各解碼后的字符，連成一個(gè)字符串。
return this.utf8to16(str.join(''));
}
};
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