What's the simplest way to call Http GET url using Delphi?

Question

There's a web services I want to call in my application, I can use it with importing the WSDL or by just use "HTTP GET" with the URL and parameters, so I prefer the later because it's simple thing.

I know I can use indy idhttp.get, to do the job, but this is very simple thing and I don't want to add complex indy code to my application.

UPDATE: sorry if I was not clear, I meant by "not to add complex indy code", that I don't want add indy components for just this simple task, and prefer more lighter way for that.

Answer 1

Calling a RESTful web service using Indy is pretty straight forward.

Add IdHTTP to your uses clause. Remember that IdHTTP needs the "HTTP://" prefix on your URLs.

function GetURLAsString(const aURL: string): string; var   lHTTP: TIdHTTP; begin   lHTTP := TIdHTTP.Create;   try     Result := lHTTP.Get(aURL);   finally     lHTTP.Free;   end; end; 

Answer 2

You could use the WinINet API like this:

uses WinInet;

function GetUrlContent(const Url: string): string;
var
  NetHandle: HINTERNET;
  UrlHandle: HINTERNET;
  Buffer: array[0..1024] of Char;
  BytesRead: dWord;
begin
  Result := '';
  NetHandle := InternetOpen('Delphi 5.x', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);

  if Assigned(NetHandle) then 
  begin
    UrlHandle := InternetOpenUrl(NetHandle, PChar(Url), nil, 0, INTERNET_FLAG_RELOAD, 0);

    if Assigned(UrlHandle) then
      { UrlHandle valid? Proceed with download }
    begin
      FillChar(Buffer, SizeOf(Buffer), 0);
      repeat
        Result := Result + Buffer;
        FillChar(Buffer, SizeOf(Buffer), 0);
        InternetReadFile(UrlHandle, @Buffer, SizeOf(Buffer), BytesRead);
      until BytesRead = 0;
      InternetCloseHandle(UrlHandle);
    end
    else
      { UrlHandle is not valid. Raise an exception. }
      raise Exception.CreateFmt('Cannot open URL %s', [Url]);

    InternetCloseHandle(NetHandle);
  end
  else
    { NetHandle is not valid. Raise an exception }
    raise Exception.Create('Unable to initialize Wininet');
end;

source: http://www.scalabium.com/faq/dct0080.htm

The WinINet API uses the same stuff InternetExplorer is using so you also get any connection and proxy settings set by InternetExplorer for free.

Answer 3

Actually code in accepted answer did't work for me. So I modified it a little bit so it actually returns String and gracefully closes everything after execution. Example returns retrieved data as UTF8String so it will work well for ASCII as well as for UTF8 pages.

uses WinInet;

function GetUrlContent(const Url: string): UTF8String;
var
  NetHandle: HINTERNET;
  UrlHandle: HINTERNET;
  Buffer: array[0..1023] of byte;
  BytesRead: dWord;
  StrBuffer: UTF8String;
begin
  Result := '';
  NetHandle := InternetOpen('Delphi 2009', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
  if Assigned(NetHandle) then
    try
      UrlHandle := InternetOpenUrl(NetHandle, PChar(Url), nil, 0, INTERNET_FLAG_RELOAD, 0);
      if Assigned(UrlHandle) then
        try
          repeat
            InternetReadFile(UrlHandle, @Buffer, SizeOf(Buffer), BytesRead);
            SetString(StrBuffer, PAnsiChar(@Buffer[0]), BytesRead);
            Result := Result + StrBuffer;
          until BytesRead = 0;
        finally
          InternetCloseHandle(UrlHandle);
        end
      else
        raise Exception.CreateFmt('Cannot open URL %s', [Url]);
    finally
      InternetCloseHandle(NetHandle);
    end
  else
    raise Exception.Create('Unable to initialize Wininet');
end;

Hope it helps for somebody like me who was looking for easy code how to retrieve page content in Delphi. Cheers, Aldis :)