单/多文件上传。

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

namespace AspNetTest.Common
{
    /**//// <summary>
    /// 单/多文件上传,，写的不好，见笑。.
    /// </summary>
    public class UploadFile
    {
        public UploadFile()
        {
            //
            // TODO: 在此处添加构造函数逻辑
            //
        }
        
        //上传文件默认目录，例如： UploadFiles，该值在web.config中配置
        private string initDirectory = ConfigurationSettings.AppSettings["Upload_InitDir"];
        //是否启用决定路径，该路径一般会存在数据库中。若设为绝对路径，调用不用考虑相对路径问题
        private bool useAbsolutePath = true;
        //上传路径，例如：上传路径是 Pic，那么所有的图片都会存在 UploadFiles/Pic目录下，为空时全部存在 UploadFiles目录下
        private string uploadPath = "";
        //是否启用随机文件名，随机文件名的格式是：yyyyMMddhhmmss + 3位数的随机数
        private bool useRandFileName;
        //是否自动创建日期目录，若启用，会在上传文件目录下生成 2006/4/17 这3个目录
        private bool createDateDir;
        public bool UseAbsolutePath
        {
            get
            {
                return useAbsolutePath;
            }
            set
            {
                useAbsolutePath = value;
            }
        }
        public string UploadPath
        {
            get
            {
                return uploadPath;
            }
            set
            {
                if(UseAbsolutePath)
                {
                    uploadPath = GetApplicationPath();
                }
                uploadPath += this.initDirectory + "/";
                string valueExtended = value.ToString().Trim();
                if(valueExtended != "")
                {
                    uploadPath += value;
                    if(!valueExtended.EndsWith("/"))
                    {
                        uploadPath += "/";
                    }
                }
            }
        }

        public bool UseRandFileName
        {
            get
            {
                return useRandFileName;
            }
            set
            {
                useRandFileName = value;
            }
        }
        public bool CreateDateDir
        {
            get
            {
                return createDateDir;
            }
            set
            {
                createDateDir = value;
            }
        }
        public void Upload()
        {
            HttpFileCollection hpc = HttpContext.Current.Request.Files;                
            if(hpc != null)
            {
                for(int i=0; i<hpc.Count; i++)
                {
                    HttpPostedFile file = hpc[i];
                    //判断大小
                    int fileContentLength = file.ContentLength;
                    if(fileContentLength < 1)
                    {
                        continue;;
                    }
                    int allowMaxSize = Convert.ToInt32(ConfigurationSettings.AppSettings["Upload_AllowMaxSize"]);
                    if(fileContentLength > allowMaxSize * 1024 * 1024)
                    {
                        HttpContext.Current.Response.Write("最大上传的文件只允许<b>" + Convert.ToString(allowMaxSize / 1000) + "M</b>");
                        return;
                    }
                    string fileName = Path.GetFileName(file.FileName);
                    string fileContentType = Path.GetExtension(fileName).Remove(0, 1);
                    string allowTypes = ConfigurationSettings.AppSettings["Upload_AllowTypes"];
                    //判断类型
                    if(("|"+allowTypes.ToLower()+"|").IndexOf("|"+fileContentType+"|") == -1)
                    {
                        HttpContext.Current.Response.Write("只允许上传的文件格式有：<b>" + allowTypes + "</b>");
                        return;
                    }
                    //随机文件名
                    if(UseRandFileName)
                    {
                        fileName = DateTime.Now.ToString("yyyyMMddhhmmss") + (new Random()).Next(100, 1000).ToString() + "." + fileContentType;
                    }
                    string addPath = HttpContext.Current.Server.MapPath(UploadPath);
                    if(!Directory.Exists(addPath))
                    {
                        Directory.CreateDirectory(addPath);
                    }
                    //创建日期目录
                    if(CreateDateDir)
                    {
                        addPath += DateTime.Today.Year.ToString() + @"\";
                        if(!Directory.Exists(addPath))
                        {
                            Directory.CreateDirectory(addPath);
                        }
                        addPath += DateTime.Today.Month.ToString().PadLeft(2, '0') + @"\";
                        if(!Directory.Exists(addPath))
                        {
                            Directory.CreateDirectory(addPath);
                        }
                        addPath += DateTime.Today.Day.ToString().PadLeft(2, '0') + @"\";
                        if(!Directory.Exists(addPath))
                        {
                            Directory.CreateDirectory(addPath);
                        }
                    }
                    string filePath = addPath + fileName;
                    file.SaveAs((filePath));
                    HttpContext.Current.Response.Write("<br>文件（<b>"+ fileName +"</b>）上传成功！<br>地址：");
                    HttpContext.Current.Response.Write(filePath + "<hr>");
                    WriteFilePathToDB(filePath);
                }
            }
        }
        public void WriteFilePathToDB(string path)
        {
            //将上传文件路径写入数据库
        }
        private string GetApplicationPath()
        {
            string appPath = HttpContext.Current.Request.ApplicationPath;
            if(!appPath.EndsWith("/"))
            {
                appPath += "/"; 
            }
            return appPath;
        }
    
    }
}

调用：

UploadFile oUploadFile = new UploadFile();
            oUploadFile.UseAbsolutePath = true;
            oUploadFile.UploadPath = "Pic";
            oUploadFile.CreateDateDir = true;
            oUploadFile.UseRandFileName = true;
            oUploadFile.Upload();