Base64 encoder and decoder for ActionScript 3

来源：互联网发布：英语六级怎么准备知乎编辑：程序博客网时间：2024/05/21 10:32
转自:http://foxarc.com/blog/article/60.htm
这个英文网站里面也有很多actionscript相关的好文章
Base64 encode and decode is very useful in both web application and desktop application. Here is the ActionScript 3 Base64 code.//Base64.as package com.foxarc.util{       import flash.utils.ByteArray;       public class Base64 {           private static  const encodeChars:Array =            ['A','B','C','D','E','F','G','H',           'I','J','K','L','M','N','O','P',           'Q','R','S','T','U','V','W','X',           'Y','Z','a','b','c','d','e','f',           'g','h','i','j','k','l','m','n',           'o','p','q','r','s','t','u','v',           'w','x','y','z','0','1','2','3',           '4','5','6','7','8','9','+','/'];           private static  const decodeChars: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];           public static function encode(data:ByteArray):String {               var out:Array = [];               var i:int = 0;               var j:int = 0;               var r:int = data.length % 3;               var len:int = data.length - r;               var c:int;               while (i < len) {                   c = data[i++] << 16 | data[i++] << 8 | data[i++];                   out[j++] = encodeChars[c >> 18] + encodeChars[c >> 12 & 0x3f] + encodeChars[c >> 6 & 0x3f] + encodeChars[c & 0x3f];               }               if (r == 1) {                   c = data[i++];                   out[j++] = encodeChars[c >> 2] + encodeChars[(c & 0x03) << 4] + "==";               }               else if (r == 2) {                   c = data[i++] << 8 | data[i++];                   out[j++] = encodeChars[c >> 10] + encodeChars[c >> 4 & 0x3f] + encodeChars[(c & 0x0f) << 2] + "=";               }               return out.join('');           }           public static function decode(str:String):ByteArray {               var c1:int;               var c2:int;               var c3:int;               var c4:int;               var i:int;               var len:int;               var out:ByteArray;               len = str.length;               i = 0;               out = new ByteArray();               while (i < len) {                   // c1                   do {                       c1 = decodeChars[str.charCodeAt(i++) & 0xff];                   } while (i < len && c1 == -1);                   if (c1 == -1) {                       break;                   }                   // c2                       do {                       c2 = decodeChars[str.charCodeAt(i++) & 0xff];                   } while (i < len && c2 == -1);                   if (c2 == -1) {                       break;                   }                   out.writeByte((c1 << 2) | ((c2 & 0x30) >> 4));                   // c3                   do {                       c3 = str.charCodeAt(i++) & 0xff;                       if (c3 == 61) {                           return out;                       }                       c3 = decodeChars[c3];                   } while (i < len && c3 == -1);                   if (c3 == -1) {                       break;                   }                   out.writeByte(((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2));                   // c4                   do {                       c4 = str.charCodeAt(i++) & 0xff;                       if (c4 == 61) {                           return out;                       }                       c4 = decodeChars[c4];                   } while (i < len && c4 == -1);                   if (c4 == -1) {                       break;                   }                   out.writeByte(((c3 & 0x03) << 6) | c4);               }               return out;           }       }   }
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