An ASP COM component that can fetch a file from the internet and save on your server automatically
Zhanshan Dong
Two weeks ago I migrated my webserver from a machine with Windows 98 and PWS to a machine with Windows
2000 Professional and IIS 5.0. Somehow one COM component did not work anymore in IIS 5.0. But the same
COM component works very well under PWS and Windows 98. I wrote that COM component two years ago by
using Delphi. I searched the help file in delphi for attempt to sovle the problem, I failed to do that.
I searched the web through Google. I saw the same problem somebody already asked in the web. But there
is no answer to this question. I was a little disappointed about this. But I got to solve the problem
and let my web site work properly. In one article, I found that one guy suggested another way to
download files from the internet without using UrlMon.DLL. I followed his suggestion and started to use
WinINet.DLL to create a sample program. At the very beginning, the program did not work either. I was
confused. I tried very hard in the late night. Dubugging the program step by step. Finally, I sovled the
problem and downloaded a file to my hard disk. I knew that I found the answer. The source code is pretty
simple (listed below). But the idea is very important. The COM component written in DELPHI 6.0. IF you
wnant to use the source code, you need create a new ActiveX Libray project, and add one Automation Class
to your project and add a method to the class, then copy and paste the code to your function
implementation part.
Here is the source code.
=======================
unit uMain;
{$WARN SYMBOL_PLATFORM OFF}
interface
uses
ComObj, ActiveX, AspTlb, ReadUrl_TLB, StdVcl,sysutils,classes;
type
TReadUrl = class(TASPMTSObject, IReadUrl)
protected
function DownloadFile(Source, Dest: OleVariant): OleVariant; safecall;
end;
implementation
uses windows, ComServ, Wininet;
function TReadUrl.DownloadFile(Source, Dest: OleVariant): OleVariant;
var
BSource, ADest : string;
ASource : Pchar;
hSession: HINTERNET;
hService: HINTERNET;
lpBuffer: array[0..1024 + 1] of Char;
dwBytesRead: LongWord;
myfile : file;
begin
BSource := Source;
ASource := pchar(BSource);
ADest := Dest;
assignfile(myFile,ADest);
rewrite(myFile,1);
Result := False;
hSession := InternetOpen('ReadUrl', INTERNET_OPEN_TYPE_DIRECT, nil, nil, 0);
try
if Assigned(hSession) then
begin
hService := InternetOpenUrl(hSession, ASource, nil, 0, INTERNET_FLAG_RELOAD, 0);
if Assigned(hService) then
try
while True do
begin
dwBytesRead := 1024;
InternetReadFile(hService, @lpBuffer, 1024, dwBytesRead);
if dwBytesRead = 0 then break;
lpBuffer[dwBytesRead] := #0;
blockwrite(myfile,lpBuffer,dwBytesRead);
end;
Result := True;
finally
InternetCloseHandle(hService);
end;
end;
finally
InternetCloseHandle(hSession);
end;
closefile(myfile);
end;
initialization
TAutoObjectFactory.Create(ComServer, TReadUrl, CLASS_ReadUrl,
ciMultiInstance, tmApartment);
end.
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The source code file include all you need, even the compiled DLL file.
Download source code
©董占山Zhanshan Dong
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