Question

有人可以帮我把这个代码段转换成它的.net核心等价物吗？

        Uri uri = new Uri(url);
        string filename = System.IO.Path.GetFileName(uri.LocalPath);
        string extension = Path.GetExtension(filename);

        string tempFilepath = Path.GetTempFileName() + extension;

        try
        {
            WebClient webClient = new WebClient();
            webClient.DownloadFile(url, tempFilepath);

            if (new FileInfo(tempFilepath).Length > 0)
            {
                return tempFilepath;
            }
            else {
                return null;
            }

        }
        catch (WebException e)
        {
            return null;
        }
        catch (NotSupportedException e)
        {
            return null;
        }

实际上，此代码以前是在.net 4.6中写入的应用程序中。然后前段时间，我们停止使用该应用程序。现在我正在开发.net核心中的另一个应用程序，并将做同样的事情。所以我想知道如何使用.net核心这样做？ HttpClient中DownloadFile方法的替代方法是什么？

Answer 1

这个应该这样做......

try
{
    using (var client = new HttpClient())
    {
        using (HttpResponseMessage response = client.GetAsync(url, HttpCompletionOption.ResponseHeadersRead).Result)
        {
            response.EnsureSuccessStatusCode();

            using (Stream contentStream = response.Content.ReadAsStreamAsync().Result, fileStream = new FileStream(tempFilepath, FileMode.Create, FileAccess.Write, FileShare.None, 8192, true))
            {
                var buffer = new byte[8192];
                var isMoreToRead = true;

                do
                {
                    var read = contentStream.ReadAsync(buffer, 0, buffer.Length).Result;
                    if (read == 0)
                    {
                        isMoreToRead = false;
                    }
                    else
                    {
                        fileStream.WriteAsync(buffer, 0, read);
                    }
                }

                while (isMoreToRead);
            }
        }
    }

或者您可以更加干净地实现这一点：How to implement progress reporting for Portable HttpClient

Answer 2

更简单的做法是......

        HttpClient client = new HttpClient();
        try
        {
            var response =  client.GetStringAsync(url);
            Console.WriteLine(response.Result);
        }
        catch (Exception e)
        {
            Console.WriteLine("Message :{0} ", e.Message);
        }
        finally{
            client.Dispose();
        }

目标框架： netcoreapp1.1
编辑： Visual Studio代码
应用类型：控制台应用

WebClient（.net 4.6）到HttpClient（.net核心）

2 个答案: