C# 下载文件的几种方法

1. 使用WebRequest类下载，代码如下:

WebRequest request = WebRequest.Create("http://www.walnr.com/File/Base64ToFile.exe");
WebResponse response = request.GetResponse();
if (response.ContentType.ToLower().Length > 0)
{
    using (Stream reader = response.GetResponseStream())
    {
        using (FileStream writer = new FileStream(@"D:\Base64ToFile.exe", FileMode.OpenOrCreate, FileAccess.Write))
        {
            byte[] buffer = new byte[1024];
            int c = 0;
            while ((c = reader.Read(buffer, 0, buffer.Length)) > 0)
            {
                writer.Write(buffer, 0, c);
            }
        }
    }
}

2.采用HttpResponse类下载代码如下:

HttpResponse Response = HttpContext.Current.Response;
#region    读取流程
byte[] bytes = Convert.FromBase64String("");
#endregion
// 清除缓存区流中的所有内容输出
Response.Clear();
// 设置缓冲输出为true,后台编辑的文件写到内存流中了
Response.Buffer = true;
// 设置编码格式 ContentEncoding是管字节流到文本的，而Charset是管在浏览器中显示的
//Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");
Response.Charset = "UTF-8";
// 将HTTP头添加到输出流，指定默认名
Response.AddHeader("Content-Disposition", string.Format(@"attachment;filename=""{0}""", HttpUtility.UrlEncode("文件.et")));
Response.ContentEncoding = System.Text.Encoding.UTF8;
// 设置输出流的HTTP MIME类型为application/vnd.ms-excel 
//ContentType类型的地址：        https://www.cnblogs.com/zzr-stdio/p/10692497.html
Response.ContentType = "application/vnd.ms-excel";

Response.AddHeader("Content-Length", bytes.Length.ToString());
// 将指定的文件写入HTTP内容输出流
Response.OutputStream.Write(bytes, 0, bytes.Length);
//防止文件名含中文出现乱码而进行编码
// Response.BinaryWrite(bytes);
// 向客户端发送当前所有缓冲的输出
Response.Flush();
// 将当前所有缓冲的输出关闭
Response.Close();