dotnet 通过 HttpClient 下载文件同时报告进度的方法

       private static async Task DownloadFile(string url, FileInfo file)
        {
            var httpClient = new HttpClient();
            var response = await httpClient.GetAsync(url);

            try
            {
                var n = response.Content.Headers.ContentLength;
                var stream = await response.Content.ReadAsStreamAsync();
                using(var fileStream = file.Create())
                using (stream)
                {
                    byte[] buffer = new byte[1024];
                    var readLength = 0;
                    int length;
                    while ((length = await stream.ReadAsync(buffer, 0, buffer.Length)) != 0)
                    {
                        readLength += length;

                        Console.WriteLine("下载进度" + ((double)readLength) / n * 100);

                        // 写入到文件
                        fileStream.Write(buffer, 0, length);
                    }
                }

            }
            catch (Exception e)
            {
            }
        }

                var stream = await response.Content.ReadAsStreamAsync();
                using(var fileStream = file.Create())
                using (stream)
                {
                    await stream.CopyToAsync(fileStream);
                }