.net 通过 HttpClient 下载文件同时报告进度的方法

通过 HttpClient 的 ContentLength 很多时候都可以拿到下载的内容的长度，通过 ReadAsync 可以返回当前读到的长度，将读取到的长度加起来就是已经下载的长度

看起来很简单，于是直接给代码

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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) { } }

如果不是需要获取进度，那么最简单的方法是

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

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