Base64与UTF-8

来源：互联网发布：王者荣耀聊天软件编辑：程序博客网时间：2024/06/06 09:39

本文实例讲述了JS实现对中文字符串进行utf-8的Base64编码的方法。分享给大家供大家参考，具体如下：

要进行编码的字符串：“select 用户名 from 用户”

使用JAVA进行编码，Java程序：

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String sql = "select 用户名 from 用户";
String encodeStr =new String(Base64.encode(sql.getBytes("UTF-8")));// 编码
System.out.println(encodeStr);

得到：

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c2VsZWN0IOeUqOaIt+WQjSBmcm9tIOeUqOaItw==

在Java中解码：

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sql = newString(Base64.decode(sql.getBytes()), "UTF-8");

Java代码中为什么要使用getBytes("UTF-8")呢？因为Windows和Linux环境下默认编码不同，要使你的程序在不同平台下得到相同编码，必然要指定编码

虽然Html和JS的编码都是utf-8，但JS从页面上得到的中文编码却是utf-16，所以直接对中文进行Base64编码将得到错误的结果，所以我们要先从utf-16转到utf-8再编码

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<!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+/=";
//将Ansi编码的字符串进行Base64编码
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;
} elseif (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;
}
//将Base64编码字符串转换成Ansi编码的字符串
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) {
 varout, 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));
  }
 }
 returnout;
}
function utf8to16(str) {
 varout, i, len, c;
 varchar2, char3;
 out ="";
 len = str.length;
 i = 0;
 while(i < len) {
  c = str.charCodeAt(i++);
  switch(c >> 4) {
   case0: case 1: case 2: case3: case 4: case 5: case6: case 7:
    // 0xxxxxxx
    out += str.charAt(i-1);
    break;
   case12: case 13:
    // 110x xxxx  10xx xxxx
    char2 = str.charCodeAt(i++);
    out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
    break;
   case14:
    // 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;
  }
 }
 returnout;
}
// 测试代码 开始
var de = encode64(utf16to8("select 用户名 from 用户"));
document.writeln(de+"<br>");
var ee = utf8to16(decode64(de))
document.writeln(ee);
// 测试代码 结束
//-->
</script>
</head>
<body>
</body>
</html>

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