图片上传支持预览（C#）

用到的命名空间：

 

using System.Data.SqlClient;
using System.IO;
using System.Xml;

 

 

 

<script type="text/javascript" language="javascript">
<!--
function PreviewImg()
{
    //原来的预览代码，不支持 IE7。
    var oldPreview = document.getElementById("newPreview");
    oldPreview.innerHTML = "<img src=/"" + document.getElementById("upload").value + "/" width=/"100%/" height=/"300px/" />";
   
    //新的预览代码，支持 IE6、IE7、IE8。
    var newPreview = document.getElementById("newPreview");
    newPreview.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = document.getElementById("upload").value;
   
}
//-->
    </script>

 

<input id="upload" runat="server" name="upload" type="file" style="width: 250px;
       font-size: 12px;" onchange="javascript:PreviewImg();" />

 

 

后台代码

 

 protected void btnupload_ServerClick(object sender, EventArgs e)
    {
 string strFileName = "";
 XmlDocument document = new XmlDocument();
 document.Load(Server.MapPath("UploadFile.xml"));
 XmlNodeList cn = document.SelectNodes("fileset");
 string pathfile = cn.Item(0).SelectSingleNode("upload").Attributes["path"].Value.ToString();
 string strfileExt = cn.Item(0).SelectSingleNode("fileformat").InnerText.ToString();
 if (strfileExt.IndexOf(System.IO.Path.GetExtension(upload.PostedFile.FileName)) == -1)
 {
     Page.ClientScript.RegisterStartupScript(Page.GetType(), "", "<script language='javascript'>alert('只支持.jpg文件上传。');</script>");
     return;
 }
 if ( selbanner.Value  == "-2")
 {
     Page.ClientScript.RegisterStartupScript(Page.GetType(),"","<script>alert(/"请您选择所属频道！/");</script>");
     return;
 }
 using (scn = new SqlConnection())
     {
  scn.ConnectionString = connectionstring;
  scn.Open();
  using (scm = new SqlCommand())
      {
   scm = scn.CreateCommand();
   scm.CommandType = CommandType.StoredProcedure;
   scm.CommandText = "flash_upload_ADD";

   scm.Parameters.Add("@picdiscription", SqlDbType.VarChar, 50);
   scm.Parameters["@picdiscription"].Value = this.txtdiscription.Value;

   scm.Parameters.Add("@piclink", SqlDbType.VarChar, 500);
   scm.Parameters["@piclink"].Value = this.piclink.Value;

   scm.Parameters.Add("@picname", SqlDbType.VarChar, 50);
   strFileName = pathfile + "/" + System.DateTime.Now.Year.ToString() + System.DateTime.Now.Month.ToString() + System.DateTime.Now.Day.ToString() + System.DateTime.Now.Hour.ToString() + System.DateTime.Now.Minute.ToString() + System.DateTime.Now.Millisecond.ToString() + System.IO.Path.GetExtension(upload.PostedFile.FileName);
   scm.Parameters["@picname"].Value = strFileName;

   scm.Parameters.Add("@picorder", SqlDbType.Int);
   scm.Parameters["@picorder"].Value = orderid.Value;

   string bannerids = "";
   foreach(ListItem li in selbanner.Items)
   {
       if ( li.Selected == true)
    bannerids += li.Value + ",";
   }
   scm.Parameters.Add("@banner", SqlDbType.VarChar, 8000).Value = bannerids;

   scm.Parameters.Add("@information", SqlDbType.VarChar, 50);
   scm.Parameters["@information"].Direction = ParameterDirection.Output;

   scm.ExecuteNonQuery();
   
   Page.ClientScript.RegisterStartupScript(Page.GetType(),"","<script>alert('" + scm.Parameters["@information"].Value.ToString() + "');</script>");
      }
     }
     DirectoryInfo directoryinfo = new DirectoryInfo(Server.MapPath(pathfile));
     if (!directoryinfo.Exists)
     {
  directoryinfo.Create();
     }
     upload.PostedFile.SaveAs(Server.MapPath(strFileName));
     this.txtdiscription.Value = "";
     this.piclink.Value = "";
    }