如何从HttpPostedFile创建字节数组

using System;
using System.IO;
using System.Web;

public class FileHelper
{
    public static byte[] ConvertHttpPostedFileToByteArray(HttpPostedFile postedFile)
    {
        using (BinaryReader reader = new BinaryReader(postedFile.InputStream))
        {
            using (MemoryStream memoryStream = new MemoryStream())
            {
                byte[] buffer = new byte[4096];
                int bytesRead;

                while ((bytesRead = reader.Read(buffer, 0, buffer.Length)) > 0)
                {
                    memoryStream.Write(buffer, 0, bytesRead);
                }

                return memoryStream.ToArray();
            }
        }
    }
}

byte[] byteArray = FileHelper.ConvertHttpPostedFileToByteArray(uploadedFile);