基于flash AS3.0 的BASE64编码与解码类

代码
Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/-->//调用代码：
import com.dynamicflash.utils.Base64;
//编码和解码字符串
var source:String = "Hello,world";
var encoded:String = Base64.encode(source);
trace(encoded);
var decoded:String = Base64.decode(encoded);
trace(decoded);
//编码和解码ByteArray
var obj:Object= {name:"Dynamic Flash",url:"http://dynamicflash.com"};
var source:ByteArray = new ByteArray();
source.writeObject(obj);
var encoded:String = Base64.encodeByteArray(source);
trace(encoded);
var decoded:ByteArray = Base64.decodeToByteArray(encoded);
obj = decoded.readObject();
trace(obj.name + "(" + obj.url + ")");
//Base64类代码：
package com.dynamicflash.util{
import flash.utils.ByteArray;
public class Base64 {
private static const BASE64_CHARS:String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
public static const version:String = "1.0.0";
public static function encode(data:String):String {
// Convert string to ByteArray
var bytes:ByteArray = new ByteArray();
bytes.writeUTFBytes(data);
// Return encoded ByteArray
return encodeByteArray(bytes);
}
public static function encodeByteArray(data:ByteArray):String {
// Initialise output
var output:String = "";
// Create data and output buffers
var dataBuffer:Array;
var outputBuffer:Array = new Array(4);
// Rewind ByteArray
data.position = 0;
// while there are still bytes to be processed
while (data.bytesAvailable > 0) {
// Create new data buffer and populate next 3 bytes from data
dataBuffer = new Array();
for (var i:uint = 0; i < 3 && data.bytesAvailable > 0; i++) {
dataBuffer[i] = data.readUnsignedByte();
}
// Convert to data buffer Base64 character positions and
// store in output buffer
outputBuffer[0] = (dataBuffer[0] & 0xfc) >> 2;
outputBuffer[1] = ((dataBuffer[0] & 0x03) << 4) | ((dataBuffer[1]) >> 4);
outputBuffer[2] = ((dataBuffer[1] & 0x0f) << 2) | ((dataBuffer[2]) >> 6);
outputBuffer[3] = dataBuffer[2] & 0x3f;
// If data buffer was short (i.e not 3 characters) then set
// end character indexes in data buffer to index of '=' symbol.
// This is necessary because Base64 data is always a multiple of
// 4 bytes and is basses with '=' symbols.
for (var j:uint = dataBuffer.length; j < 3; j++) {
outputBuffer[j + 1] = 64;
}
// Loop through output buffer and add Base64 characters to
// encoded data string for each character.
for (var k:uint = 0; k < outputBuffer.length; k++) {
output += BASE64_CHARS.charAt(outputBuffer[k]);
}
}
// Return encoded data
return output;
}
public static function decode(data:String):String {
// Decode data to ByteArray
var bytes:ByteArray = decodeToByteArray(data);
// Convert to string and return
return bytes.readUTFBytes(bytes.length);
}
public static function decodeToByteArray(data:String):ByteArray {
// Initialise output ByteArray for decoded data
var output:ByteArray = new ByteArray();
// Create data and output buffers
var dataBuffer:Array = new Array(4);
var outputBuffer:Array = new Array(3);
// While there are data bytes left to be processed
for (var i:uint = 0; i < data.length; i += 4) {
// Populate data buffer with position of Base64 characters for
// next 4 bytes from encoded data
for (var j:uint = 0; j < 4 && i + j < data.length; j++) {
dataBuffer[j] = BASE64_CHARS.indexOf(data.charAt(i + j));
}
// Decode data buffer back into bytes
outputBuffer[0] = (dataBuffer[0] << 2) + ((dataBuffer[1] & 0x30) >> 4);
outputBuffer[1] = ((dataBuffer[1] & 0x0f) << 4) + ((dataBuffer[2] & 0x3c) >> 2);
outputBuffer[2] = ((dataBuffer[2] & 0x03) << 6) + dataBuffer[3];
// Add all non-padded bytes in output buffer to decoded data
for (var k:uint = 0; k < outputBuffer.length; k++) {
if (dataBuffer[k+1] == 64) break;
output.writeByte(outputBuffer[k]);
}
}
// Rewind decoded data ByteArray
output.position = 0;
// Return decoded data
return output;
}
public function Base64() {
throw new Error("Base64 class is static container only");
}
}
}

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参考：

http://www.cnblogs.com/sevenyuan/archive/2009/12/01/1614768.html