Javascript base64编码实现代码


复制代码 代码如下:

/*
* base64编码
*/
var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var base64DecodeChars = 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);
function base64encode(str) {
  var out, i, len;
  var c1, c2, c3;
  len = str.length;
  i = 0;
  out = "";
  while(i < len) {
c1 = str.charCodeAt(i++) & 0xff;
if(i == len)
{
out += base64EncodeChars.charAt(c1 >> 2);
   out += base64EncodeChars.charAt((c1 & 0x3) << 4);
   out += "==";
   break;
}
c2 = str.charCodeAt(i++);
if(i == len)
{
   out += base64EncodeChars.charAt(c1 >> 2);
   out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));
   out += base64EncodeChars.charAt((c2 & 0xF) << 2);
   out += "=";
   break;
}
c3 = str.charCodeAt(i++);
out += base64EncodeChars.charAt(c1 >> 2);
out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));
out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6));
out += base64EncodeChars.charAt(c3 & 0x3F);
  }
  return out;
}
function base64decode(str) {
  var c1, c2, c3, c4;
  var i, len, out;
  len = str.length;
  i = 0;
  out = "";
  while(i < len) {
/* c1 */
do {
   c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
} while(i < len && c1 == -1);
if(c1 == -1)
   break;
/* c2 */
do {
   c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
} while(i < len && c2 == -1);
if(c2 == -1)
   break;
out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));
/* c3 */
do {
   c3 = str.charCodeAt(i++) & 0xff;
   if(c3 == 61)
  return out;
   c3 = base64DecodeChars[c3];
} while(i < len && c3 == -1);
if(c3 == -1)
   break;
out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));
/* c4 */
do {
   c4 = str.charCodeAt(i++) & 0xff;
   if(c4 == 61)
  return out;
   c4 = base64DecodeChars[c4];
} while(i < len && c4 == -1);
if(c4 == -1)
   break;
out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
   }
  return out;
}
function utf16to8(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;
}
function utf8to16(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;
}
/*
* base64编码 End
*/
var m = 'hello';
m = base64encode(m);

这是一个例子:
复制代码 代码如下:

<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<TITLE>Javascript Base64 Demo</TITLE>
<script language=javascript>
/*
* base64编码
*/
var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var base64DecodeChars = 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);
function base64encode(str) {
  var out, i, len;
  var c1, c2, c3;
  len = str.length;
  i = 0;
  out = "";
  while(i < len) {
c1 = str.charCodeAt(i++) & 0xff;
if(i == len)
{
out += base64EncodeChars.charAt(c1 >> 2);
   out += base64EncodeChars.charAt((c1 & 0x3) << 4);
   out += "==";
   break;
}
c2 = str.charCodeAt(i++);
if(i == len)
{
   out += base64EncodeChars.charAt(c1 >> 2);
   out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));
   out += base64EncodeChars.charAt((c2 & 0xF) << 2);
   out += "=";
   break;
}
c3 = str.charCodeAt(i++);
out += base64EncodeChars.charAt(c1 >> 2);
out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));
out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6));
out += base64EncodeChars.charAt(c3 & 0x3F);
  }
  return out;
}
function base64decode(str) {
  var c1, c2, c3, c4;
  var i, len, out;
  len = str.length;
  i = 0;
  out = "";
  while(i < len) {
/* c1 */
do {
   c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
} while(i < len && c1 == -1);
if(c1 == -1)
   break;
/* c2 */
do {
   c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
} while(i < len && c2 == -1);
if(c2 == -1)
   break;
out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));
/* c3 */
do {
   c3 = str.charCodeAt(i++) & 0xff;
   if(c3 == 61)
  return out;
   c3 = base64DecodeChars[c3];
} while(i < len && c3 == -1);
if(c3 == -1)
   break;
out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));
/* c4 */
do {
   c4 = str.charCodeAt(i++) & 0xff;
   if(c4 == 61)
  return out;
   c4 = base64DecodeChars[c4];
} while(i < len && c4 == -1);
if(c4 == -1)
   break;
out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
   }
  return out;
}
function utf16to8(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;
}
function utf8to16(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;
}
/*
* base64编码 End
*/
function doit() {
  var f = document.f
  f.output.value = base64encode(utf16to8(f.source.value))
  f.decode.value = utf8to16(base64decode(f.output.value))
}
</script>
</HEAD>
<BODY>
<H1>Javascript Base64 Demo</H1>
<FORM NAME="f">
原码<BR>
<TEXTAREA NAME="source" ROWS=4 COLS=80 WRAP="soft"></TEXTAREA><BR><BR>
Base64 encode<BR>
<TEXTAREA NAME="output" ROWS=4 COLS=80 WRAP="soft"></TEXTAREA><BR><BR>
Base64 decode<BR>
<TEXTAREA NAME="decode" ROWS=4 COLS=80 WRAP="soft"></TEXTAREA><BR><BR>
<INPUT TYPE=BUTTON VALUE="转换" ONCLICK="doit();">
</FORM>
</BODY>
</html>



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