处理和抛出异常

try
{
}
catch (System.Exception e)
{
  throw new System.Exception("error",e);
}
catch
{
   throw;
}
finally
{
}

抛出异常
throw e;

自定义异常
public class WidgetException:System.ApplicationException
{
    Widget mWidget;
    public Widget ErrorWidget
    {
        get
        {
            return mWidget;
        }
    }
  
    public WidgetException(Widget W, string s) :base(S)
    {
          mWidget = w;
    }
}