<p><br>
<head><br>
<br>
<script language=javascript><br>
var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";<br>
var base64DecodeChars = new Array(<br>
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,<br>
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,<br>
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,<br>
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,<br>
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,<br>
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,<br>
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,<br>
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);<br>
function base64encode(str) {<br>
var out, i, len;<br>
var c1, c2, c3;<br>
len = str.length;<br>
i = 0;<br>
out = "";<br>
while(i < len) {<br>
c1 = str.charCodeAt(i++) & 0xff;<br>
if(i == len)<br>
{<br>
out += base64EncodeChars.charAt(c1 >> 2);<br>
out += base64EncodeChars.charAt((c1 & 0x3) << 4);<br>
out += "==";<br>
break;<br>
}<br>
c2 = str.charCodeAt(i++);<br>
if(i == len)<br>
{<br>
out += base64EncodeChars.charAt(c1 >> 2);<br>
out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));<br>
out += base64EncodeChars.charAt((c2 & 0xF) << 2);<br>
out += "=";<br>
break;<br>
}<br>
c3 = str.charCodeAt(i++);<br>
out += base64EncodeChars.charAt(c1 >> 2);<br>
out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));<br>
out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6));<br>
out += base64EncodeChars.charAt(c3 & 0x3F);<br>
}<br>
return out;<br>
}<br>
function base64decode(str) {<br>
var c1, c2, c3, c4;<br>
var i, len, out;<br>
len = str.length;<br>
i = 0;<br>
out = "";<br>
while(i < len) {<br>
/* c1 */<br>
do {<br>
c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];<br>
} while(i < len && c1 == -1);<br>
if(c1 == -1)<br>
break;<br>
/* c2 */<br>
do {<br>
c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];<br>
} while(i < len && c2 == -1);<br>
if(c2 == -1)<br>
break;<br>
out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));<br>
/* c3 */<br>
do {<br>
c3 = str.charCodeAt(i++) & 0xff;<br>
if(c3 == 61)<br>
return out;<br>
c3 = base64DecodeChars[c3];<br>
} while(i < len && c3 == -1);<br>
if(c3 == -1)<br>
break;<br>
out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));<br>
/* c4 */<br>
do {<br>
c4 = str.charCodeAt(i++) & 0xff;<br>
if(c4 == 61)<br>
return out;<br>
c4 = base64DecodeChars[c4];<br>
} while(i < len && c4 == -1);<br>
if(c4 == -1)<br>
break;<br>
out += String.fromCharCode(((c3 & 0x03) << 6) | c4);<br>
}<br>
return out;<br>
}<br>
function utf16to8(str) {<br>
var out, i, len, c;<br>
out = "";<br>
len = str.length;<br>
for(i = 0; i < len; i++) {<br>
c = str.charCodeAt(i);<br>
if ((c >= 0x0001) && (c <= 0x007F)) {<br>
out += str.charAt(i);<br>
} else if (c > 0x07FF) {<br>
out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));<br>
out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));<br>
out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));<br>
} else {<br>
out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));<br>
out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));<br>
}<br>
}<br>
return out;<br>
}<br>
function utf8to16(str) {<br>
var out, i, len, c;<br>
var char2, char3;<br>
out = "";<br>
len = str.length;<br>
i = 0;<br>
while(i < len) {<br>
c = str.charCodeAt(i++);<br>
switch(c >> 4)<br>
{<br>
case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:<br>
// 0xxxxxxx<br>
out += str.charAt(i-1);<br>
break;<br>
case 12: case 13:<br>
// 110x xxxx 10xx xxxx<br>
char2 = str.charCodeAt(i++);<br>
out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));<br>
break;<br>
case 14:<br>
// 1110 xxxx 10xx xxxx 10xx xxxx<br>
char2 = str.charCodeAt(i++);<br>
char3 = str.charCodeAt(i++);<br>
out += String.fromCharCode(((c & 0x0F) << 12) |<br>
((char2 & 0x3F) << 6) |<br>
((char3 & 0x3F) << 0));<br>
break;<br>
}<br>
}<br>
return out;<br>
}</p>
<p>function doit() {<br>
var f = document.f<br>
f.output.value = base64encode(utf16to8(f.source.value))<br>
f.decode.value = utf8to16(base64decode(f.output.value))<br>
}<br>
</script><br>
</head><br>
<body></p>
<h1>Base64</h1>
<br>
<form NAME="f"><br>
原码<br>
<br>
<textarea NAME="source" ROWS=4 COLS=60 WRAP="soft">
Base64 encode
Base64 decode
Base64 encode
Base64 decode
