首先我想说明我不能发布源代码，因为这个项目很大。我正在尝试在 iPad 设备上下载一个大文件 (500+ MB)。最初我尝试使用 URLLoader，但后来我意识到 iPad 设备的内存资源非常有限。比我认为 URLStream 会以块的形式下载文件，并且使用 FileStream 我可以将这些块保存在设备上（就像这个AS3：URLStream 将文件保存到桌面？），但我错了，当我尝试下载时设备崩溃了大文件，因为设备的 RAM 不够（更确切地说，这变得太大：System.privateMemory） 有谁知道如何分块下载文件，是否可以不使用“套接字连接”？
提前致谢。
编辑：这是我使用的代码（注释行是 FileStream las 仅在文件下载后关闭的版本。
package components.streamDownloader
{
import flash.events.Event;
import flash.events.EventDispatcher;
import flash.events.IOErrorEvent;
import flash.events.OutputProgressEvent;
import flash.events.ProgressEvent;
import flash.events.SecurityErrorEvent;
import flash.filesystem.File;
import flash.filesystem.FileMode;
import flash.filesystem.FileStream;
import flash.net.URLRequest;
import flash.net.URLStream;
import flash.system.System;
import flash.utils.ByteArray;
/**
*
*/
public class StreamDownloader extends EventDispatcher
{
[Event(name="DownloadComplete", type="com.tatstyappz.net.DownloadEvent")]
[Event(name="Error", type="com.tatstyappz.net.DownloadEvent")]
//--------------------------------------------------------------------------
//
// Constructor
//
//--------------------------------------------------------------------------
public function StreamDownloader()
{
}
//--------------------------------------------------------------------------
//
// Variables
//
//--------------------------------------------------------------------------
private var file:File;
//private var fileStream:FileStream;
private var urlRequest:URLRequest;
private var urlStream:URLStream;
private var waitingForDataToWrite:Boolean = false;
//--------------------------------------------------------------------------
//
// API
//
//--------------------------------------------------------------------------
public function download(urlRequest:URLRequest, file:File):void {
init();
this.urlRequest = urlRequest;
this.file = file;
//fileStream.open(file, FileMode.WRITE);
urlStream.load(urlRequest);
}
//--------------------------------------------------------------------------
//
// Event handlers
//
//--------------------------------------------------------------------------
//----------------------------------
// urlStream events
//----------------------------------
protected function urlStream_openHandler(event:Event):void
{
waitingForDataToWrite = false;
dispatchEvent(event.clone());
}
protected function urlStream_progressHandler(event:ProgressEvent):void
{
trace("MEMORY:", System.totalMemoryNumber / 1024 / 1024, "MEMORY P:", System.privateMemory / 1024 / 1024, "FREE MEMORY:", System.freeMemory / 1024 / 1024, "PROGRESS:", event.bytesLoaded / event.bytesTotal );
if(waitingForDataToWrite){
writeToDisk();
}
}
protected function urlStream_completeHandler(event:Event):void
{
if(urlStream.bytesAvailable > 0)
{
writeToDisk();
}
//fileStream.close();
destory();
dispatchEvent(event.clone());
// dispatch additional DownloadEvent
dispatchEvent(new StreamDownloadEvent(StreamDownloadEvent.DOWNLOAD_COMPLETE, urlRequest, file));
}
protected function urlStream_securityErrorHandler(event:SecurityErrorEvent):void
{
dispatchEvent(new StreamDownloadEvent(StreamDownloadEvent.ERROR, urlRequest, file, event.errorID.toString()));
destory();
}
protected function urlStream_ioErrorHandler(event:IOErrorEvent):void
{
dispatchEvent(new StreamDownloadEvent(StreamDownloadEvent.ERROR, urlRequest, file, event.errorID.toString()));
destory();
}
//----------------------------------
// fileStream events
//----------------------------------
protected function fileStream_outputProgressHandler(event:OutputProgressEvent):void
{
waitingForDataToWrite = true;
}
protected function fileStream_ioErrorHandler(event:IOErrorEvent):void
{
dispatchEvent(new StreamDownloadEvent(StreamDownloadEvent.ERROR, urlRequest, file, event.errorID.toString()));
destory();
}
//--------------------------------------------------------------------------
//
// Utils
//
//--------------------------------------------------------------------------
private function init():void
{
urlStream = new URLStream();
//fileStream = new FileStream();
urlStream.addEventListener(Event.OPEN, urlStream_openHandler);
urlStream.addEventListener(ProgressEvent.PROGRESS, urlStream_progressHandler);
urlStream.addEventListener(Event.COMPLETE, urlStream_completeHandler);
urlStream.addEventListener(IOErrorEvent.IO_ERROR, urlStream_ioErrorHandler);
urlStream.addEventListener(SecurityErrorEvent.SECURITY_ERROR, urlStream_securityErrorHandler);
//fileStream.addEventListener(OutputProgressEvent.OUTPUT_PROGRESS, fileStream_outputProgressHandler)
//fileStream.addEventListener(IOErrorEvent.IO_ERROR, fileStream_ioErrorHandler);
}
private function destory():void
{
urlStream.removeEventListener(Event.OPEN, urlStream_openHandler);
urlStream.removeEventListener(ProgressEvent.PROGRESS, urlStream_progressHandler);
urlStream.removeEventListener(Event.COMPLETE, urlStream_completeHandler);
urlStream.removeEventListener(IOErrorEvent.IO_ERROR, urlStream_ioErrorHandler);
urlStream.removeEventListener(SecurityErrorEvent.SECURITY_ERROR, urlStream_securityErrorHandler);
//fileStream.removeEventListener(OutputProgressEvent.OUTPUT_PROGRESS, fileStream_outputProgressHandler)
//fileStream.removeEventListener(IOErrorEvent.IO_ERROR, fileStream_ioErrorHandler);
urlStream = null;
//fileStream = null;
}
private function writeToDisk():void {
/*var fileData:ByteArray = new ByteArray();
urlStream.readBytes(fileData, 0, urlStream.bytesAvailable);
fileStream.writeBytes(fileData,0,fileData.length);
waitingForDataToWrite = false;*/
var bytes:ByteArray = new ByteArray();
urlStream.readBytes( bytes );
var fs:FileStream = new FileStream();
fs.open( file, FileMode.APPEND );
fs.writeBytes( bytes );
fs.close();
}
}
}