c# - mscorlib.dll 中出现类型为 "System.ArgumentException"的第一次机会异常

Question

  try
        {
            FtpWebRequest req = (FtpWebRequest)WebRequest.Create("ftp path");
            req.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
            using (var resp = (FtpWebResponse)req.GetResponse())
            {
                Console.WriteLine(resp.WelcomeMessage);
            }
            FtpWebResponse res = (FtpWebResponse)req.GetResponse();
            Stream rs = res.GetResponseStream();
            StreamReader read1 = new StreamReader(res.GetResponseStream());// prob A
            Console.WriteLine(read1.ReadToEnd());
            Console.WriteLine("Directory is compleate,status(0)",
            res.StatusDescription);
            read1.Close();
            rs.Close();
        }
        catch (Exception e1)
        {
            Console.WriteLine(e1.Message);
        }

我正在尝试通过 C# 访问 ftp 服务器。

然而，代码错误并出现异常:
“System.ArgumentException”类型的第一次机会异常发生在 mscorlib.dll 中。流不可读。

我们将不胜感激。

Answer 1

将所有 IDisposable 资源放在 using(...) {...} 中。该技术可以防止资源泄漏/关闭资源调用:

try {
  FtpWebRequest req = (FtpWebRequest)WebRequest.Create("ftp path");
  req.Method = WebRequestMethods.Ftp.ListDirectoryDetails;

  // Response: we're going to work wuth respose within "using" block only
  using (FtpWebResponse resp = (FtpWebResponse)req.GetResponse()) {
    Console.WriteLine(resp.WelcomeMessage);

    // Reader: once again reader's opened once and called within using only
    using (StreamReader reader = new StreamReader(resp.GetResponseStream())) {
      Console.WriteLine(reader.ReadToEnd());
      Console.WriteLine("Directory is complete, status(0)", resp.StatusDescription);
    }
  }
catch (Exception ex) { // <- Bad idea to catch all possible exceptions without "throw;"
  Console.WriteLine(ex.Message);
}