IdHttp只需获取响应代码 [英] IdHttp Just Get Response Code

问题描述

我使用idhttp（Indy）做一些网站检查。所有我想要做的是在我的请求发送后检查服务器的响应代码，我不想实际需要从服务器接收HTML输出，因为我只监控200 OK代码，任何其他代码意味着有一些形式的问题。

我已经查找了idhttp帮助文档，唯一的方法可以看到可能做到这一点是将代码分配给一个 MemoryStream 然后立即清除它，但是这不是很有效，并且使用不需要的内存。有没有办法只是调用一个网站并获得响应，但是忽略发回的HTML效率更高，不会浪费内存？

目前，代码看起来像这样。但是这只是我还没有测试的示例代码，我只是用它来解释我正在做什么。

 过程Button1Click（Sender：TObject）; 
 
 var 
 http：TIdHttp; 
 s：TStream; 
 url：string; 
 code：integer; 
 
 begin 
 
 s：= TStream.Create（）; 
 http：= Tidhttp.create（）; 
 url：='http://www.WEBSITE.com'; 
 
 try 
 
 http.get（url，s）; 
 code：= http.ResponseCode; 
 ShowMessage（IntToStr（code））; 
 
 finally 
 
 s.Free（）; 
 http.Free（）; 
 
 end; 
  

解决方案

TIdHTTP.Head（） 是最好的选择。但是，作为一种替代方案，在最新版本中，您可以调用 TIdHTTP.Get（），其中包含一个零目标 TStream 或$ code> TIdEventStream ，没有分配任何事件处理程序，它仍将读取服务器的数据，但不存储在任何地方。

无论哪种方式，还要记住，如果服务器发回ResponseCode故障，TIdHTTP将引发异常（除非您使用 AIgnoreReplies 参数来指定特定的ResponseCode值有兴趣的话，所以你应该说明一下，例如：

  procedure Button1Click（Sender：TObject）; 
 var 
 http：TIdHttp; 
 url：string; 
 code：integer; 
 begin 
 url：='http://www.WEBSITE.com'; 
 http：= TIdHTTP.Create（nil）; 
尝试
尝试
 http.Head（url）; 
 code：= http.ResponseCode; 
除了
在E：EIdHTTPProtocolException do 
 code：= http.ResponseCode; //或：code：= E.ErrorCode; 
结束
 ShowMessage（IntToStr（code））; 
 finally 
 http.Free（）; 
结束
结束
 
程序Button2Click（Sender：TObject）; 
 var 
 http：TIdHttp; 
 url：string; 
 code：integer; 
 begin 
 url：='http://www.WEBSITE.com'; 
 http：= TIdHTTP.Create（nil）; 
尝试
尝试
 http.Get（url，nil）; 
 code：= http.ResponseCode; 
除了
在E：EIdHTTPProtocolException do 
 code：= http.ResponseCode; //或：code：= E.ErrorCode; 
结束
 ShowMessage（IntToStr（code））; 
 finally 
 http.Free（）; 
结束
结束
  

I'm using idhttp (Indy) to do some website checking. All I want it to do is check the response code from the server after my request has been sent, I don't want to actually have to receive the HTML output from the server as I'm only monitoring for a 200 OK code, any other code meaning there is an issue of some form.

I've looked up idhttp help documents and the only way I could see to possible do this would be to assign the code to a MemoryStream and then just clear it straight away, however that isn't very efficient and uses memory that isn't needed. Is there a way to just call a site and get the response but ignore the HTML sent back that is more efficient and doesn't waste memory?

Currently the code would look something like this. However this is just sample code which I haven't tested yet, I'm just using it to explain what I'm trying to do.

Procedure Button1Click(Sender: TObject);

var
http : TIdHttp;
s : TStream;
url : string;
code : integer;

begin 

   s := TStream.Create();
   http := Tidhttp.create();
   url := 'http://www.WEBSITE.com';

   try

    http.get(url,s);
    code := http.ResponseCode;
    ShowMessage(IntToStr(code));

   finally

   s.Free();
   http.Free();

end;

解决方案

TIdHTTP.Head() is the best option. However, as an alternative, in the latest version you can call TIdHTTP.Get() with a nil destination TStream, or a TIdEventStream with no event handlers assigned, and it will still read the server's data but not store it anywhere.

Either way, also keep in mind that if the server sends back a failure ResponseCode, TIdHTTP will raise an exception (unless you use the AIgnoreReplies parameter to specify specific ResponseCode values you are interested in), so you should account for that as well, eg:

procedure Button1Click(Sender: TObject);
var
  http : TIdHttp;
  url : string;
  code : integer;
begin
  url := 'http://www.WEBSITE.com';
  http := TIdHTTP.Create(nil);
  try
    try
      http.Head(url);
      code := http.ResponseCode;
    except
      on E: EIdHTTPProtocolException do
        code := http.ResponseCode; // or: code := E.ErrorCode;
    end;
    ShowMessage(IntToStr(code));
  finally
    http.Free();
  end;
end; 

procedure Button2Click(Sender: TObject);
var
  http : TIdHttp;
  url : string;
  code : integer;
begin
  url := 'http://www.WEBSITE.com';
  http := TIdHTTP.Create(nil);
  try
    try
      http.Get(url, nil);
      code := http.ResponseCode;
    except
      on E: EIdHTTPProtocolException do
        code := http.ResponseCode; // or: code := E.ErrorCode;
    end;
    ShowMessage(IntToStr(code));
  finally
    http.Free();
  end;
end; 

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