一个文件上传的类

namespace Wmj
{
public class MyUpload
{
private System.Web.HttpPostedFile postedFile=null;
private string savePath="";
private string extension="";
private int fileLength=0;
//显示该组件使用的参数信息
public string Help
{
  get{
 string helpstring;
 helpstring="<font size=3>MyUpload myUpload=new MyUpload(); //构造函数";
 helpstring+="myUpload.PostedFile=file1.PostedFile;//设置要上传的文件";
 helpstring+="myUpload.SavePath=\"e:\\\";//设置要上传到服务器的路径，默认c:\\";
 helpstring+="myUpload.FileLength=100; //设置上传文件的最大长度，单位k，默认1k";
 helpstring+="myUpload.Extension=\"doc\";设置上传文件的扩展名，默认txt";
 helpstring+="label1.Text=myUpload.Upload();//开始上传，并显示上传结果</font>";
 helpstring+="<font size=3 color=red>Design By WengMingJun 2001-12-12 All Right Reserved!</font>";
 return helpstring;
  }
}

public System.Web.HttpPostedFile PostedFile
{
get
{
return postedFile;
}
set
{
postedFile=value;
}
}

public string SavePath
{
  get
  {
 if(savePath!="") return savePath;
 return "c:\\";
  }
  set
  {
 savePath=value;
  }
}

public int FileLength
{
  get
  {
 if(fileLength!=0) return fileLength;
 return 1024;
  }
  set
  {
 fileLength=value*1024;
  }
}

public string Extension
{
  get
  {
 if(extension!="") return extension;
 return "txt";
  }
  set
  {
 extension=value;
  }
}

public string PathToName(string path)
{
 int pos=path.LastIndexOf("\\");
 return path.Substring(pos+1);
}

public string Upload()
{
if(PostedFile!=null)
{
try{
 string fileName=PathToName(PostedFile.FileName);
 if(!fileName.EndsWith(Extension)) return "You must select "+Extension+" file!";
 if(PostedFile.ContentLength>FileLength) return "File too big!";
 PostedFile.SaveAs(SavePath+fileName);
 return "Upload File Successfully!";
}
catch(System.Exception exc)
{return exc.Message;}
}
return "Please select a file to upload!";
}
}
}

用csc /target:Library Wmj.cs 编译成dll供以后多次调用
调用举例
<%@page language="C#" runat="server"%>
<%@import namespace="Wmj"%>
<script language="C#" runat="server">
void Upload(object sender,EventArgs e)
{
 MyUpload myUpload=new MyUpload();
 // label1.Text=myUpload.Help;
 myUpload.PostedFile=file1.PostedFile;
 myUpload.SavePath="e:\\";
 myUpload.FileLength=100;
 label1.Text=myUpload.Upload();
}
</script>
<form enctype="multipart/form-data" runat="server">
<input type="file" id="file1" runat="server"/>
<asp:Button id="button1" Text="Upload" OnClick="Upload" runat="server"/>
<asp:Label id="label1" runat="server"/>
</form>