asp.net文件上传解决方案（图片上传、单文件上传、多文件上传、检查文件类型）

前端技术 2023/09/02 .NET

小编之前也介绍了许多ASP.NET文件上传的解决案例，今天来个asp.net文件上传大集合。

1 使用标准HTML来进行图片上传
前台代码：

<body> 
 <form id=\"form1\" runat=\"server\"> 
 <div> 
  <table> 
   <tr> 
    <td colspan=\"2\" style=\"height: 21px\" > 
     使用标准HTML来进行图片上传</td> 
   </tr> 
   <tr> 
    <td style=\"width: 400px\"> 
     <input id=\"InputFile\" style=\"width: 399px\" type=\"file\" runat=\"server\" /></td> 
    <td style=\"width: 80px\"> 
     <asp:Button ID=\"UploadButton\" runat=\"server\" Text=\"上传图片\" OnClick=\"UploadButton_Click\" /></td> 
   </tr> 
   <tr> 
    <td colspan=\"2\" > 
     <asp:Label ID=\"Lb_Info\" runat=\"server\" ForeColor=\"Red\"></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; 

public partial class _Default : System.Web.UI.Page 
{ 
 protected void Page_Load(object sender, EventArgs e) 
 { 

 } 
 protected void UploadButton_Click(object sender, EventArgs e) 
 { 
  string uploadName = InputFile.Value;//获取待上传图片的完整路径，包括文件名 
  //string uploadName = InputFile.PostedFile.FileName; 
  string pictureName = \"\";//上传后的图片名，以当前时间为文件名，确保文件名没有重复 
  if (InputFile.Value != \"\") 
  { 
   int idx = uploadName.LastIndexOf(\".\"); 
   string suffix = uploadName.Substring(idx);//获得上传的图片的后缀名 
   pictureName = DateTime.Now.Ticks.ToString() + suffix; 
  } 
  try 
  { 
   if (uploadName != \"\") 
   { 
    string path = Server.MapPath(\"~/images/\"); 
    InputFile.PostedFile.SaveAs(path + pictureName); 
   } 
  } 
  catch (Exception ex) 
  { 
   Response.Write(ex); 
  } 
 } 
}

2 单文件上传
这是最基本的文件上传，在asp.net1.x中没有这个FileUpload控件，只有html的上传控件，那时候要把html控件转化为服务器控件， 很不好用。其实所有文件上传的美丽效果都是从这个FileUpload控件衍生，第一个例子虽然简单却是根本。
前台代码： 

<body> 
 <form id=\"form1\" runat=\"server\"> 
 <div> 
  <table style=\"width: 90%\"> 
   <tr> 
    <td style=\"width: 159px\" colspan=2> 
     <strong><span style=\"font-size: 10pt\">最简单的单文件上传</span></strong></td> 
   </tr> 
   <tr> 
    <td style=\"width: 600px\"> 
     <asp:FileUpload ID=\"FileUpload1\" runat=\"server\" Width=\"600px\" /></td> 
    <td align=left> 
     <asp:Button ID=\"FileUpload_Button\" runat=\"server\" Text=\"上传图片\" OnClick=\"FileUpload_Button_Click\" /></td> 
   </tr> 
   <tr> 
    <td colspan=2> 
     <asp:Label ID=\"Upload_info\" runat=\"server\" ForeColor=\"Red\" Width=\"767px\"></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; 

public partial class _Default : System.Web.UI.Page 
{ 
 protected void Page_Load(object sender, EventArgs e) 
 { 

 } 
 protected void FileUpload_Button_Click(object sender, EventArgs e) 
 { 
  try 
  { 
   if (FileUpload1.PostedFile.FileName == \"\") 
   //if (FileUpload1.FileName == \"\") 
   //if (!FileUpload1.HasFile)  //获取一个值，该值指示 System.Web.UI.WebControls.FileUpload 控件是否包含文件。包含文件，则为 true；否则为 false。 
   { 
    this.Upload_info.Text = \"请选择上传文件！\"; 
   } 
   else 
   { 
    string filepath = FileUpload1.PostedFile.FileName; //得到的是文件的完整路径,包括文件名，如：C:\\Documents and Settings\\Administrator\\My Documents\\My Pictures\\20022775_m.jpg 
    //string filepath = FileUpload1.FileName;    //得到上传的文件名20022775_m.jpg 
    string filename = filepath.Substring(filepath.LastIndexOf(\"\\\\\") + 1);//20022775_m.jpg 
    string serverpath = Server.MapPath(\"~/images/\") + filename;//取得文件在服务器上保存的位置C:\\Inetpub\\wwwroot\\WebSite1\\images\\20022775_m.jpg 
    FileUpload1.PostedFile.SaveAs(serverpath);//将上传的文件另存为 
    this.Upload_info.Text = \"上传成功！\"; 
   } 
  } 
  catch (Exception ex) 
  { 
   this.Upload_info.Text = \"上传发生错误！原因是：\" + ex.ToString(); 
  } 
 } 
}


3、多文件上传
前台代码：

<body> 
 <form id=\"form1\" runat=\"server\"> 
 <div> 
 <table style=\"width: 343px\"> 
   <tr> 
    <td style=\"width: 100px\"> 
     多文件上传</td> 
    <td style=\"width: 100px\"> 
    </td> 
   </tr> 
   <tr> 
    <td style=\"width: 100px\"> 
     <asp:FileUpload ID=\"FileUpload1\" runat=\"server\" Width=\"475px\" /> 
     </td> 
    <td style=\"width: 100px\"> 
     </td> 
   </tr> 
   <tr> 
    <td style=\"width: 100px\"> 
     <asp:FileUpload ID=\"FileUpload2\" runat=\"server\" Width=\"475px\" /></td> 
    <td style=\"width: 100px\"> 
    </td> 
   </tr> 
   <tr> 
    <td style=\"width: 100px\"> 
     <asp:FileUpload ID=\"FileUpload3\" runat=\"server\" Width=\"475px\" /></td> 
    <td style=\"width: 100px\"> 
    </td> 
   </tr> 
   <tr> 
    <td style=\"width: 100px\"> 
     <asp:Button ID=\"bt_upload\" runat=\"server\" OnClick=\"bt_upload_Click\" Text=\"一起上传\" /> 
     <asp:Label ID=\"lb_info\" runat=\"server\" ForeColor=\"Red\" Width=\"448px\"></asp:Label></td> 
    <td style=\"width: 100px\"> 
    </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; 

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) 
 { 
  if (FileUpload1.PostedFile.FileName == \"\" && FileUpload2.PostedFile.FileName == \"\" && FileUpload3.PostedFile.FileName == \"\") 
  { 
   this.lb_info.Text = \"请选择文件！\"; 
  } 
  else 
  { 
   HttpFileCollection myfiles = Request.Files; 
   for (int i = 0; i < myfiles.Count; i++) 
   { 
    HttpPostedFile mypost = myfiles[i]; 
    try 
    { 
     if (mypost.ContentLength > 0) 
     { 
      string filepath = mypost.FileName;//C:\\Documents and Settings\\Administrator\\My Documents\\My Pictures\\20022775_m.jpg 
      string filename = filepath.Substring(filepath.LastIndexOf(\"\\\\\") + 1);//20022775_m.jpg 
      string serverpath = Server.MapPath(\"~/images/\") + filename;//C:\\Inetpub\\wwwroot\\WebSite2\\images\\20022775_m.jpg 
      mypost.SaveAs(serverpath); 
      this.lb_info.Text = \"上传成功！\"; 
     } 
    } 
    catch (Exception ex) 
    { 
     this.lb_info.Text = \"上传发生错误！原因：\" + ex.Message.ToString(); 
    } 
   } 
  } 
 } 
}

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.getElementById(\"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; 
  } 
 } 
}

为大家推荐一个专题，供大家学习：《ASP.NET文件上传汇总》

是不是内容很精彩，喜欢的朋友就收藏起来吧，以后在遇到ASP.NET文件上传问题的时候能够有所帮助。

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