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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）

2014年11月30日 作者：lijiao

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 SettingsAdministratorMy DocumentsMy Pictures20022775_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:InetpubwwwrootWebSite1images20022775_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 SettingsAdministratorMy DocumentsMy Pictures20022775_m.jpg 
      string filename = filepath.Substring(filepath.LastIndexOf("") + 1);//20022775_m.jpg 
      string serverpath = Server.MapPath("~/images/") + filename;//C:InetpubwwwrootWebSite2images20022775_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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