c# 上传图片

javascript 现在图片之后先显示出来(不支持firefox)

function change_photo(obj,width,height)
    {
          var imgDIV = document.getElementById("imgDIV");
          var str = obj.value || obj;
          try{
               imgDIV.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = str;
               imgDIV.style.width=width;
               imgDIV.style.height=height;
               imgDIV.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").sizingMethod = 'scale';
               document.getElementById('img').style.display = "none";
          }
          catch(e)
          {
                // 上传不是图片文件的处理。
         
          }
      }

<div id="imgDIV" style="width:258px;height:63px;
               filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);
              text-align: center;">
        <img ID="img"><!--height="300px"  Width="500px" nerror="change_photo(this.src,140,70);"-->
    </div>
    <input type="file" name="files"
          onpropertychange="change_photo(this,800,600);" />

 

=====================================

Boolean fileOK = false;
String path = Server.MapPath("/NewFolder/");
string strFileType="";
if (FileUpload1.HasFile)
{
    String fileExtension = System.IO.Path.GetExtension(FileUpload1.FileName).ToLower();
    String[] allowedExtensions = { ".gif", ".png", ".jpeg", ".jpg" };
    for (int i = 0; i < allowedExtensions.Length; i++)
    {
        if (fileExtension == allowedExtensions[i])
        {
fileOK = true;
strFileType=fileExtension;
break;
        }
    }
}

if (fileOK)
{
    try
    {
        //FileUpload1.PostedFile.SaveAs(path + FileUpload1.FileName);
        string strFileName = System.DateTime.Now.ToString("yyyyMMdd")+(new Random()).Next(100) + strFileType;
        FileUpload1.PostedFile.SaveAs(path + strFileName);
        //Label1.Text = "File uploaded!";
        Image1.ImageUrl = "/NewFolder/" + strFileName;
        //Page.RegisterStartupScript("", "<script>alert('上传成功!')</script>");
    }
    catch (Exception ex)
    {
        //Label1.Text = "File could not be uploaded.";
        Page.RegisterStartupScript("", "<script>alert('上传失败!')</script>");
    }
}
else
{
    //Label1.Text = "Cannot accept files of this type.";
    Page.RegisterStartupScript("", "<script>alert('上传文件类型错误!')</script>");
}