const Url = 'http://www.cnblogs.com';
procedure TForm1.Button1Click(Sender: TObject);
var
  stream: TStringStream;
  idHttpObj: TIdHTTP;
begin
try
  stream := TStringStream.Create('', TEncoding.UTF8); //中文就不会乱码了
  idHttpObj := TIdHTTP.Create(nil);
  idHttpObj.Get(Url, stream);
  Memo1.Text := stream.DataString;
finally
  idHttpObj.Free;
  stream.Free;
end;

(*********************************************************
    获取web返回的信息
    paramJson 参数，格式如下
    '{"name":"myname","ID":"12356"}'
*********************************************************)
function GetWebData(URL:string;paramJson:string):string;stdcall;
var
  slist : TStringList;
  http : TIdHttp;
begin
  try
    http := TIdHttp.Create;
    slist := TStringList.Create;
    slist.Text := 'json='+paramJson;//加入json，方便php调用
    result := http.Post(URL,slist);
  finally
    http.Free;
    slist.Free;
  end;
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
  memo1.lines.Add( GetWebData(URL,'{"key":"DFDGBFSE$#$$R","name":"中文","id":123456}') );
end;