图片不存在使用默认图片代替的实例

web.config：

<configuration>
  <appsettings>
    <add key="dmpic" value="bgimages/moren.jpg" />
  </appsettings>
</configuration>

相应.cs页面：

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();
    }            
}