通用 模拟下载文件保存方法

起始：

需要使用weiapi 请求外部接口获取文件并保存。

使用方法：

使用

WebRequest 模拟Http请求 获取返回流 。

发现问题：

本地搭建webapi模拟外接口测试时发现，无法获取到webapi返回的文件流。

解决方法：

修改方法。使用httpclient,得到返回的 httpresponsemessage。

经过测试发现，可以兼容各种返回结果。

代码重现：

请求地址的代码：
 string filePath = "d:333.xls";

            try
            {
                var stream = new FileStream(filePath, FileMode.Open);
                HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
                response.Content = new StreamContent(stream);
                response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
                {
                    FileName = "333.xls"
                };
                return response;
            }
            catch
            {
                return new HttpResponseMessage(HttpStatusCode.NoContent);
            }

使用HttpRequest模拟请求接收：

    HttpWebRequest request = WebRequest.Create(Url) as HttpWebRequest;
                    HttpWebResponse response = request.GetResponse() as HttpWebResponse;
                    string file = "xxx"; //获取文件名
                    Stream responseStream = response.GetResponseStream();
                    //创建本地文件写入流
                    Stream stream = new FileStream(file, FileMode.Create);
                    byte[] bArr = new byte[1024];
                    int size = responseStream.Read(bArr, 0, (int)bArr.Length);
                    while (size > 0)
                    {
                        stream.Write(bArr, 0, size);
                        size = responseStream.Read(bArr, 0, (int)bArr.Length);
                    }
                    stream.Close();
                    responseStream.Close();

使用HttpClient模拟请求接收：

 //用 request  没法获取到文件流 改用client
                    HttpResponseMessage responseMessage = new HttpResponseMessage();
                    using (HttpClient httpClient = new HttpClient())
                    {
                        Task<HttpResponseMessage> responseMessageTask = httpClient.GetAsync(Url);
                        responseMessage = responseMessageTask .Result;
                    }
                    string file = ""; //生成文件名和路径
                    Stream stream = new FileStream(file, FileMode.Create);
                    var responseStream = responseMessage .Content.ReadAsStreamAsync().Result;
                    byte[] bArr = new byte[1024];
                    int size = responseStream.Read(bArr, 0, (int)bArr.Length);
                    while (size > 0)
                    {
                        stream.Write(bArr, 0, size);
                        size = responseStream.Read(bArr, 0, (int)bArr.Length);
                    }
                    responseStream.Close();
                    stream.Close();