fphttpclient

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fphttpclient is supplied with FPC as part of the fcl-web package, and can be used by itself as well.

Examples

Get body of an HTTP page

uses fphttpclient;

Var
  S : String;

begin
  With TFPHttpClient.Create(Nil) do
    try
      S:=Get(ParamStr(1));
  finally
    Free;
  end;
  Writeln('Got : ',S);
end.

If you want to write even less lines of code, in FPC 2.7.1 you can use the class method:

s := TFPCustomHTTPClient.SimpleGet('http://a_site/a_page');

Upload a file using POST

Use TFPHTTPClient.FileFormPost() to do: add exact example code

Get external IP address

If your computer is connected to the internet via a LAN (cabled or wireless), the IP address of your network card most probably is not your external IP address.

You can retrieve your external IP address from e.g. your router or an external site. The code below tries to get it from an external site (thanks to JoStudio on the forum for the inspiration: [1]):

{$mode objfpc}{$H+}

uses
  Classes, SysUtils, fphttpclient, RegexPr;

function GetExternalIPAddress: string;
var
  HTTPClient: TFPHTTPClient;
  IPRegex: TRegExpr;
  RawData: string;
begin
  try
    HTTPClient:=TFPHTTPClient.Create(nil);
    IPRegex:=TRegExpr.Create;
    try
      //returns something like:
      {
<html><head><title>Current IP Check</title></head><body>Current IP Address: 44.151.191.44</body></html>        
      }
      RawData:=HTTPClient.Get('http://checkip.dyndns.org');
      // adjust for expected output; we just capture the first IP address now:
      IPRegex.Expression:=RegExprString('\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b');
      //or
      //\b(?:\d{1,3}\.){3}\d{1,3}\b
      if IPRegex.Exec(RawData) then
      begin
        result:=IPRegex.Match[0];
      end
      else
      begin
        result:='Got invalid results getting external IP address. Details:'+LineEnding+
          RawData;
      end;
    except
      on E: Exception do
      begin
        result:='Error retrieving external IP address: '+E.Message;
      end;
    end;
  finally
    HTTPClient.Free;
    IPRegex.Free;
  end;
end;

begin
  writeln('External IP address:');
  writeln(GetExternalIPAddress);
end.