Asp.net文件的上传与下载

在我们实际的应用项目开发中，文件的上传和下载都是是必不可少的，可以说是随处可见。对于DotNet下的文件上传已经是一件再简单不过的事情了，.NET提供了强大的类库System.IO 来实现IO的所有操作。对于文件的下载也是非常简单的事情，下面我将总结一些我的实际经验，希望能给初学者们一点帮助。

首先是文件的上传，文件上传必须要保证ASP.NET用户对你所要操作的服务器端文件夹有写的权限，这样剩下的事情就非常easy了，示例代码如下:

 /**//// <summary>
        /// 文件上传
        /// </summary>
        /// <param name="filename">上传文件路径</param>
  private bool SaveFile(filename)
        {            
            string filePath=Request.PhysicalApplicationPath+"\\"+filename;                 
            try
            {                 
                this.excelfilepath.PostedFile.SaveAs(filePath);  
                return true;
            }
            catch(UnauthorizedAccessException ex)
            {
                Response.Write("<script>alert(\"没有写入权限，访问失败！详情："+ex.ToString()+"\");</script>");
                return false;
            }
            catch(Exception ex)
            {
                Response.Write("<script>alert(\"文件上传失败！详情："+ex.ToString()+"建议：文件可能太大！\");</script>");
                return false;
            }
            
        }

对于文件的下载我总结了两种方法，其实都是大同小异，示例代码如下:
方法一:  

/**//// <summary>
        /// 文件下载
        /// </summary>
        /// <param name="filename">下载文件物理路径</param>
        public static void DownLoadFile(string path)
        { 
            System.Web.HttpContext contxt=System.Web.HttpContext.Current;
            if (path != "")
            {
                //string path = HttpContext.Current.Server.MapPath(filename);
                System.IO.FileInfo file = new System.IO.FileInfo(path);
                if (file.Exists)
                {                    
                    contxt.Response.Clear();
                    contxt.Response.AddHeader("Content-Disposition", "attachment; filename=" + contxt.Server.UrlEncode(file.Name));
                    contxt.Response.AddHeader("Content-Length", file.Length.ToString());
                    contxt.Response.ContentEncoding=System.Text.Encoding.Default;
                    contxt.Response.Charset="gb2312";
                    contxt.Response.ContentType = "application/octet-stream";
                    contxt.Response.Filter.Close();
                    contxt.Response.WriteFile(file.FullName);               
                    contxt.Response.End();
                }
                else
                {

                    contxt.Response.Write("This file does not exist.");

                }
            }
        }

方法二:

    /**//// <summary>
        /// 文件下载
        /// </summary>
        /// <param name="filepath"></param>
        public static void DownLoadFileStream(string filepath)
        {
            System.Web.HttpContext contxt=System.Web.HttpContext.Current;
            if(!File.Exists(filepath))
            {
                throw new Exception("该文件不存在!");
            }
            //读取文件
            FileStream DownFiles = File.OpenRead(filepath);  
            byte[] fileCont = new byte[DownFiles.Length];
            DownFiles.Read(fileCont,0,(int)DownFiles.Length);
            contxt.Response.Clear();
            contxt.Response.AddHeader("Content-Disposition", "attachment; filename=" + contxt.Server.UrlEncode(DownFiles.Name));
            contxt.Response.AddHeader("Content-Length", DownFiles.Length.ToString());
            contxt.Response.ContentEncoding=System.Text.Encoding.Default;
            contxt.Response.Charset="gb2312";
            contxt.Response.BinaryWrite(fileCont);
            contxt.Response.End();
        }