以编程方式下载文件 [英] Programmatically downloading file

问题描述

我正在尝试使用C#4.5以编程方式登录到第三方网站，然后从该网站的另一个页面下载一个csv文件.我尝试使用以下方法.我没有收到任何错误，但似乎下载了他们登录页面的内容并保存 它是一个csv文件，而不是包含数据的实际csv文件.

Using C# 4.5,I'm trying to programmatically log-on to a third-party website and then download a csv file from another page on that site. I tried using following approach.I dont get any errors but it seems to download the contents of their logon page and save it as a csv file instead of the actual csv file having data.

另外，如果我在登录后阅读了响应流，就会发现我重新获得了登录网页.

Also,if I read the response stream after logging in, I see that I'm getting the log-on webpage back.

我在这里想念什么吗?

What am I missing here please?

另外，我还需要张贴表单的名称.如何实现?请告知.

Plus, I need to post the name of the form as well.How do I achieve that?Please advise. 

谢谢.

//Log-on to website and post user and password
    var request = new HttpRequestMessage(HttpMethod.Post, myLogonURL);
    request.Content = new StringContent("{\"user\":\"abcd\",\"password\":test}", Encoding.UTF8, "application/x-www-form-urlencoded");                                                            
    var sendTask = client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
    var response = sendTask.Result.EnsureSuccessStatusCode();

    //Download the file
    request = new HttpRequestMessage(HttpMethod.Get, fileDownloadURL);
    sendTask = client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);

    response = sendTask.Result.EnsureSuccessStatusCode();
    var httpStream = await response.Content.ReadAsStreamAsync();


    //Save the downloaded file
    using (var fileStream = File.Create(downloadedFilePath))
    using (var reader = new StreamReader(httpStream)) {
        httpStream.CopyTo(fileStream);
        fileStream.Flush();
    }

推荐答案

为什么不先看看是否可以使它与curl配合使用，以确保它不是服务器，附带问题?

Why don't you see if you can get it working with something like curl first, to make sure it's not a server-side issue?

很可能是如果没有适当的凭据，服务器将无法提供csv文件，这可能需要登录并维护会话(Cookie等).  冷的请求可能会重定向到登录页面.

It could very well be that the server won't serve the csv file without appropriate credentials, which may require logging in and maintaining a session (cookies, etc.).  A cold request is likely to be redirected to a sign in page.

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