关于多线程下载总是有失败的困扰，请高手帮忙看看代码有什么问题(100分)。
以下是具体的代码实现，请高手看看有没有需要改进的地方。谢谢！
procedure TDownload.Execute;var idHTTP : TIdHTTP; isExcetpion:Boolean; urlindex:integer; url1:string;begin urlindex:=aManager.ThisJob.iUrlIndex; iLeft := aManager.arDLFThread[iIndex].iOffsetEnd - iThisBegin; aManager.arThisDownloadSize[iIndex] := 0; Repeat begin isExcetpion:= true; idHTTP := TidHTTP.Create(nil); try iThisBegin := aManager.arDLFThread[iIndex].iOffsetBegin + aManager.arDLFThread[iIndex].iOffsetDownload; idHTTP.HandleRedirects := True; idHTTP.ReadTimeout := 30000; idHTTP.Request.UserAgent := 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; Maxthon)'; idHTTP.Request.Connection:='Keep-Alive'; idHTTP.Request.ContentRangeStart := iThisBegin; idHTTP.Request.ContentRangeEnd := aManager.arDLFThread[iIndex].iOffsetEnd; url1:=aManager.thisJob.iUrls[urlindex]; idHTTP.DoRequest(hmGet, url1, nil, nil); while not aManager.arStop[iIndex] and (iLeft > 0) do if iLeft > BufferSize then begin idHTTP.ReadBuffer(Buffer, BufferSize); fs.WriteBuffer(Buffer, BufferSize); aManager.arDLFThread[iIndex].iOffsetDownload := aManager.arDLFThread[iIndex].iOffsetDownload + BufferSize; aManager.arThisDownloadSize[iIndex] := aManager.arThisDownloadSize[iIndex] + BufferSize; iLeft := iLeft - BufferSize; aManager.arDLFThread[iIndex].iState := 1; end else begin idHTTP.ReadBuffer(Buffer, iLeft); fs.WriteBuffer(Buffer, iLeft); aManager.arDLFThread[iIndex].iOffsetDownload := aManager.arDLFThread[iIndex].iOffsetDownload + iLeft; aManager.arThisDownloadSize[iIndex] := aManager.arThisDownloadSize[iIndex] + iLeft; iLeft := 0; aManager.arDLFThread[iIndex].iState := 1; end; isExcetpion := true; except isExcetpion := false; if urlindex<aManager.ThisJob.iurlsCount-1 then begin urlindex:=urlindex+1; end else begin urlindex:=0; aManager.arDLFThread[iIndex].iState := 2; end; end; idHTTP.Free; end; until isExcetpion; fs.Free; aManager.arStop[iIndex] := False; aManager.arStoped[iIndex] := True; aManager.arDLFThread[iIndex].iState := 1; end;
