javascript 用base64解码后中文乱码的问题

网上查了好久，又结合自己的分析，终于查到了原因：UTF8页面的编码在存储时实际上还是用的UTF-16！

解决方法：解码后把utf8还原为utf16即可。

附上网上找的utf8与utf16互相转换的实现：

//utf-16转utf8

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;

},

//utf-8转utf-16

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;

}