FileCommon.cs

生成文件存储的虚拟路径：

private static string GenerateVirtualFilePath()
        {
            Byte[] b =  Guid.NewGuid().ToByteArray(); 
            StringBuilder virtualFilePath = new StringBuilder();
            for(Int32 i = 0; i < b.Length; i+=2)
            {
                Int32 folderName = b[i]*256 + b[i+1];
                virtualFilePath.AppendFormat("{0}\\", folderName.ToString());
            }
            return virtualFilePath.ToString();    
        }

存储Client端上传的文件

public static string Save(string saveRoot, HttpPostedFile entity)
        {
            string fileName = Path.GetFileName(entity.FileName);
            string savePath = Path.Combine(saveRoot, GenerateVirtualFilePath());
            if(!Directory.Exists(savePath))
                Directory.CreateDirectory(savePath);
            savePath = Path.Combine(savePath, fileName);
            entity.SaveAs(savePath);
            return savePath;
        }

简单的替换字符串的操作，解决频繁的替换成Web访问路径

public static string MapWebPath(string fileName, string saveRoot, string webRoot)
        {
            return fileName.Replace(saveRoot, webRoot);
        }

将Post到客户端的函数

public static void DownLoad(System.Web.UI.Page page, string filePath)
        { 
            string fileName = Path.GetFileName(filePath);
            fileName = HttpUtility.UrlPathEncode(fileName);
            page.Response.AppendHeader("content-disposition", "attachment; filename=" + fileName);
            page.Response.ContentType = "application/octet-stream";
            page.Response.WriteFile(filePath);
            page.Response.End();
        }

验证文件类型

public static bool ValidateFileType(string fileType, string fileExtention)
        {
            string[] fileTypeCollection = fileType.Split(',');
            foreach(string type in fileTypeCollection)
            {
                if(fileExtention.ToLower() == type.ToLower())
                    return true;
            }

            return false;
        }