使用ASP.NET上传图片汇总2

来源：互联网发布：木村拓哉女儿知乎编辑：程序博客网时间：2024/06/06 10:40

4 客户端检查上传文件类型(以上传图片为例)

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">     <title>客户端检查上传文件类型</title>     <script language="javascript">     function Check_FileType()     {         var str=document.getElementByIdx_x("FileUpload1").value;         var pos=str.lastIndexOf(".");         var lastname=str.substring(pos,str.length);         if(lastname.toLowerCase()!=".jpg"&&lastname.toLowerCase()!=".gif")         {             alert("您上传的文件类型为"+lastname+"，图片必须为.jpg,.gif类型");             return false;         }         else         {             return true;         }             }     </script> </head> <body>     <form id="form1" runat="server">     <div>         <table>             <tr>                 <td colspan="2">                     客户端检查上传文件类型</td>                             </tr>             <tr>                 <td style="width: 444px">                     <asp:FileUpload ID="FileUpload1" runat="server" Width="432px" /></td>                 <td style="width: 80px">                     <asp:Button ID="bt_upload" runat="server" Text="上传图片" OnClick="bt_upload_Click" OnClientClick="return Check_FileType()" /></td>             </tr>             <tr>                 <td colspan="2" style="height: 21px">                     <asp:Label ID="lb_info" runat="server" ForeColor="Red" Width="515px"></asp:Label></td>                             </tr>         </table>         </div>     </form> </body> </html>

注意：点击上传时先触发客户端事件OnClientClick="return Check_FileType()"

using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class _Default : System.Web.UI.Page  {     protected void Page_Load(object sender, EventArgs e)     {     }     protected void bt_upload_Click(object sender, EventArgs e)     {         try         {             if (FileUpload1.PostedFile.FileName == "")             {                 this.lb_info.Text = "请选择文件！";             }             else             {                 string filepath = FileUpload1.PostedFile.FileName;                 //if (!IsAllowedExtension(FileUpload1))                 //{                 //    this.lb_info.Text = "上传文件格式不正确！";                 //}                 if (IsAllowedExtension(FileUpload1) == true)                 {                     string filename = filepath.Substring(filepath.LastIndexOf("\\") + 1);                     string serverpath = Server.MapPath("~/images/") + filename;                     FileUpload1.PostedFile.SaveAs(serverpath);                     this.lb_info.Text = "上传成功！";                 }                 else                 {                     this.lb_info.Text = "请上传图片！";                 }             }         }         catch (Exception ex)         {             this.lb_info.Text = "上传发生错误！原因：" + ex.ToString();         }     }     private static bool IsAllowedExtension(FileUpload upfile)     {         string strOldFilePath = "";         string strExtension="";         string[] arrExtension ={ ".gif", ".jpg", ".bmp", ".png" };         if (upfile.PostedFile.FileName != string.Empty)         {             strOldFilePath = upfile.PostedFile.FileName;//获得文件的完整路径名             strExtension = strOldFilePath.Substring(strOldFilePath.LastIndexOf("."));//获得文件的扩展名，如：.jpg             for (int i = 0; i < arrExtension.Length; i++)             {                 if (strExtension.Equals(arrExtension[i]))                 {                     return true;                 }             }         }         return false;     } }

注意：若去掉客户端的脚本和客户端事件OnClientClick="return Check_FileType()"，在后台代码
改为：

if (!IsAllowedExtension(FileUpload1))                 {                     this.lb_info.Text = "上传文件格式不正确！";                 } else if (IsAllowedExtension(FileUpload1) == true)

即变成服务器端检查上传文件类型。

5 服务器端检查上传文件的类型（文件内部真正的格式）

<body>     <form id="form1" runat="server">     <div>         <table>             <tr>                 <td colspan="2">                     服务器检查上传文件类型</td>                             </tr>             <tr>                 <td style="width: 444px">                     <asp:FileUpload ID="FileUpload1" runat="server" Width="432px" /></td>                 <td style="width: 80px">                     <asp:Button ID="bt_upload" runat="server" Text="上传图片" OnClick="bt_upload_Click" /></td>             </tr>             <tr>                 <td colspan="2" style="height: 21px">                     <asp:Label ID="lb_info" runat="server" ForeColor="Red" Width="515px"></asp:Label></td>                             </tr>         </table>         </div>     </form> </body>

后台代码：

using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using System.IO; public partial class _Default : System.Web.UI.Page  {     protected void Page_Load(object sender, EventArgs e)     {     }     protected void bt_upload_Click(object sender, EventArgs e)     {         try         {             if (FileUpload1.PostedFile.FileName == "")             {                 this.lb_info.Text = "请选择文件！";             }             else             {                 string filepath = FileUpload1.PostedFile.FileName;                 if (IsAllowedExtension(FileUpload1) == true)                 {                     string filename = filepath.Substring(filepath.LastIndexOf("\\") + 1);                     string serverpath = Server.MapPath("images/") + filename;                     FileUpload1.PostedFile.SaveAs(serverpath);                     this.lb_info.Text = "上传成功！";                 }                 else                 {                     this.lb_info.Text = "请上传图片";                 }             }         }         catch (Exception error)         {             this.lb_info.Text = "上传发生错误！原因：" + error.ToString();         }     }     private static bool IsAllowedExtension(FileUpload upfile)     {         FileStream fs = new FileStream(upfile.PostedFile.FileName, FileMode.Open, FileAccess.Read);         BinaryReader r = new BinaryReader(fs);         string fileclass = "";         byte buffer;         try         {             buffer = r.ReadByte();             fileclass = buffer.ToString();             buffer = r.ReadByte();             fileclass += buffer.ToString();         }         catch         {                       }         r.Close();         fs.Close();         if (fileclass == "255216" || fileclass == "7173"||fileclass=="6677"||fileclass=="13780")//说明255216是jpg;7173是gif;6677是BMP,13780是PNG;7790是exe,8297是rar         {             return true;         }         else         {             return false;         }     } }

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