网上找到的Base64执行速度都不怎么快，原因是代码对Flash执行机制没有针对性优化。 下面给出优化过的Base64

必须使用才能完整编译

package {           import flash.utils.ByteArray;        /*  * 优化Base64  * 主要优化执行方式，尽量减少调用函数和尽可能不使用循环  * 优化后提升执行速度是原来的10倍  * Directed by kiwiw3  * */    public class MyBase64 {                        public static const version:String = "2.0.0";               public static function encode(data:String):String {                var bytes:ByteArray = new ByteArray();                bytes.writeUTFBytes(data);                                return encodeByteArray(bytes);            }                        private static const BASE64_CHARARR:Vector.
    
      = new 
     
      [65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,48,49,50,51,52,53,54,55,56,57,43,47,61];          public static function encodeByteArray(data:ByteArray):String {                var output:ByteArray = new ByteArray();                       var opbuf0:int;   var opbuf1:int;   var opbuf2:int;   var opbuf3:int;      var dblen:int = 0;   var resultlen:uint = data.length;   var position:uint = 0;   var oplen:uint = 0;            while (resultlen > 0) {                if (resultlen >= 3) {     dblen = 3;     resultlen -= 3;    }else {     dblen = resultlen;     resultlen = 0;    }                        opbuf0 = (data[position] & 0xfc) >> 2;        if(dblen>=1)                opbuf1 = ((data[position] & 0x03) << 4) | ((data[position + 1]) >> 4);    else    opbuf1 = 64;        if(dblen>=2)                opbuf2 = ((data[position + 1] & 0x0f) << 2) | ((data[position + 2]) >> 6);    else    opbuf2 = 64;        if(dblen>=3)                opbuf3 = data[position + 2] & 0x3f;    else    opbuf3 = 64;                            output[oplen]= BASE64_CHARARR[opbuf0];        output[oplen+1]= BASE64_CHARARR[opbuf1];        output[oplen+2]= BASE64_CHARARR[opbuf2];    output[oplen+3]= BASE64_CHARARR[opbuf3];                    position += 3;    oplen += 4;                }       return output.readUTFBytes(oplen);        }                    public static function decode(data:String):String {                var bytes:ByteArray = decodeToByteArray(data);                                return bytes.readUTFBytes(bytes.length);            }                    public static function decodeToByteArray(_data:String):ByteArray {                var output:ByteArray = new ByteArray();      var data:ByteArray = new ByteArray();   data.writeUTFBytes(_data);      var databuf0:int;   var databuf1:int;   var databuf2:int;   var databuf3:int;      var resultlen:uint = data.length;   var position:uint = 0;   var oplen:uint = 0;               while (resultlen>0) {            databuf0=find(data[position]);        if (resultlen >= 1)    {     databuf1=find(data[int(position+ 1)]);    }        if (resultlen >= 2)    {     databuf2=find(data[int(position+ 2)]);    }        if (resultlen >= 3) {     databuf3=find(data[int(position+3)]);    }                             if (databuf1 != 64) {     output[oplen] = (databuf0 << 2) + ((databuf1 & 0x30) >> 4);     if (databuf2 != 64) {      output[oplen + 1] = ((databuf1 & 0x0f) << 4) + ((databuf2 & 0x3c) >> 2);        if (databuf3 != 64) {       output[oplen+ 2] = ((databuf2 & 0x03) << 6) + databuf3;      }     }    }        position += 4;    oplen += 3;    resultlen -= 4;            }            return output;            }                        public function MyBase64() {                throw new Error("Base64 class is static container only");            }    private inline function find(val:int):int {   if (val >= 65 && val<=90) {    return val-65;   }else if (val >= 97 && val<=122) {    return 26+val-97;   }else if (val >= 48 && val<=57) {    return 52+val-48;   }else if (val==43) {    return 62;   }else if (val==47) {    return 63;   }else if (val==61) {    return 64;   }  }    }    }