Flash AS3 Base64

Flash AS3 Base64 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，其中inline 内联的find方法需要3kis.com的flex sdk补丁才难正常编译。

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) { find(databuf0,data[position]); if (resultlen >= 1) { find(databuf1,data[position+ 1]); }

if (resultlen >= 2) { find(databuf2,data[position+ 2]); }

if (resultlen >= 3) { find(databuf3,data[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"); }

inline function find(retval:int,val:int):void { if (val >= 65 && val<=90) { retval = val-65; }else if (val >= 97 && val<=122) { retval = 26+val-97; }else if (val >= 48 && val<=57) { retval = 52+val-48; }else if (val==43) { retval = 62; }else if (val==47) { retval = 63; }else if (val==61) { retval = 64; } } } }

网上原版如下： package com.kis.utils{

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; }