Use JS to perform Base64 encoding of utf-8 on Chinese strings

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<style type="text/css">
<!--
body{
  margin:0px;
  padding:0px;
}
body,td{
  font-size:9pt;
}
-->
</style>
<script type="text/javascript">
<!--
var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
//Encode the Ansi-encoded string to Base64
function encode64(input) {
	var output = "";
	var chr1, chr2, chr3 = "";
	var enc1, enc2, enc3, enc4 = "";
	var i = 0;
	do {
		chr1 = input.charCodeAt(i++);
		chr2 = input.charCodeAt(i++);
		chr3 = input.charCodeAt(i++);
		enc1 = chr1 >> 2;
		enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
		enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
		enc4 = chr3 & 63;
		if (isNaN(chr2)) {
			enc3 = enc4 = 64;
		} else if (isNaN(chr3)) {
			enc4 = 64;
		}
		output = output + keyStr.charAt(enc1) + keyStr.charAt(enc2)
				+ keyStr.charAt(enc3) + keyStr.charAt(enc4);
		chr1 = chr2 = chr3 = "";
		enc1 = enc2 = enc3 = enc4 = "";
	} while (i < input.length);
	return output;
}
//Convert Base64 encoded string to Ansi encoded string
function decode64(input) {
	var output = "";
	var chr1, chr2, chr3 = "";
	var enc1, enc2, enc3, enc4 = "";
	var i = 0;

	if (input.length % 4 != 0) {
		return "";
	}
	var base64test = / [^ A-Za-z0-9 \ + \ / \ =] / g;
	if (base64test.exec(input)) {
		return "";
	}
	do {
		enc1 = keyStr.indexOf(input.charAt(i++));
		enc2 = keyStr.indexOf(input.charAt(i++));
		enc3 = keyStr.indexOf(input.charAt(i++));
		enc4 = keyStr.indexOf(input.charAt(i++));
		chr1 = (enc1 << 2) | (enc2 >> 4);
		chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
		chr3 = ((enc3 & 3) << 6) | enc4;

		output = output + String.fromCharCode(chr1);
		if (enc3 != 64) {
			output += String.fromCharCode(chr2);
		}
		if (enc4 != 64) {
			output += String.fromCharCode(chr3);
		}
		chr1 = chr2 = chr3 = "";
		enc1 = enc2 = enc3 = enc4 = "";
	} while (i < input.length);
	return output;
}

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;
}

// start the test code
var de = encode64(utf16to8("select username from user"));
document.writeln(de+"<br>");
var ee = utf8to16 (decode64 (de))
document.writeln(ee);
// end of test code

//-->
</script>
</head>
<body>
</body>
</html>

Why use getBytes("UTF-8") in Java code? Because the default encoding in Windows and Linux environments is different, to make your program get the same encoding on different platforms, you must specify the encoding.

Although the encoding of Html and JS are both utf-8, the Chinese encoding obtained by JS from the page is utf-16, so Base64 encoding directly on Chinese will get wrong results, so we have to switch from utf-16 to utf-8 before encoding

Use JS to perform Base64 encoding of utf-8 on Chinese strings

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