JavaScript BASE64算法实现(完美解决中文乱码)

JavaScript 的 BASE64 算法

var BASE64={    enKey: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/',    deKey: 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  ),    encode: function(src){    //用一个数组来存放编码后的字符，效率比用字符串相加高很多。    var str=new Array();    var ch1, ch2, ch3;    var pos=0;    //每三个字符进行编码。    while(pos+3<=src.length){      ch1=src.charCodeAt(pos++);      ch2=src.charCodeAt(pos++);      ch3=src.charCodeAt(pos++);      str.push(this.enKey.charAt(ch1>>2), this.enKey.charAt(((ch1<<4)+(ch2>>4))&0x3f));      str.push(this.enKey.charAt(((ch2<<2)+(ch3>>6))&0x3f), this.enKey.charAt(ch3&0x3f));    }    //给剩下的字符进行编码。    if(pos<src.length){      ch1=src.charCodeAt(pos++);      str.push(this.enKey.charAt(ch1>>2));      if(pos<src.length){        ch2=src.charCodeAt(pos);        str.push(this.enKey.charAt(((ch1<<4)+(ch2>>4))&0x3f));        str.push(this.enKey.charAt(ch2<<2&0x3f), '=');      }else{        str.push(this.enKey.charAt(ch1<<4&0x3f), '==');      }    }    //组合各编码后的字符，连成一个字符串。    return str.join('');  },    decode: function(src){    //用一个数组来存放解码后的字符。    var str=new Array();    var ch1, ch2, ch3, ch4;    var pos=0;    //过滤非法字符，并去掉'='。    src=src.replace(/[^A-Za-z0-9/+//]/g, '');    //decode the source string in partition of per four characters.    while(pos+4<=src.length){      ch1=this.deKey[src.charCodeAt(pos++)];      ch2=this.deKey[src.charCodeAt(pos++)];      ch3=this.deKey[src.charCodeAt(pos++)];      ch4=this.deKey[src.charCodeAt(pos++)];      str.push(String.fromCharCode(        (ch1<<2&0xff)+(ch2>>4), (ch2<<4&0xff)+(ch3>>2), (ch3<<6&0xff)+ch4));    }    //给剩下的字符进行解码。    if(pos+1<src.length){      ch1=this.deKey[src.charCodeAt(pos++)];      ch2=this.deKey[src.charCodeAt(pos++)];      if(pos<src.length){        ch3=this.deKey[src.charCodeAt(pos)];        str.push(String.fromCharCode((ch1<<2&0xff)+(ch2>>4), (ch2<<4&0xff)+(ch3>>2)));      }else{        str.push(String.fromCharCode((ch1<<2&0xff)+(ch2>>4)));      }    }    //组合各解码后的字符，连成一个字符串。    return str.join('');  }};

使用方法：

var str='hello world!';var enstr=BASE64.encode(str);alert(enstr);var destr=BASE64.decode(enstr);alert(destr);