.NET图片不存在使用默认图片代替

<configuration>

  <appSettings>

    <add key="dmPic" value="bgImages/moren.jpg" />

  </appSettings>

</configuration>

if (sdr.Read())

{

    this.lblDianMianMingCheng.Text = sdr["BuJuGongSiName"].ToString();

    DianMianId = sdr["BuJuID"].ToString();

    if (sdr["BuJuCarPhoto"].ToString() == "")

    {

        this.ImageDianMian.ImageUrl = ConfigurationManager.AppSettings["dmPic"].ToString();//重点之处

    }

    else {

        this.ImageDianMian.ImageUrl = sdr["BuJuCarPhoto"].ToString();   

    }           

}