处理QueryString

首先，声明 private const String KEY_ID = "id";

private bool ReadQueryString(out int Id)
        {
            Id = -1;
            //
            // Let this function throw an exception if the QueryString contains
            // out of range or poorly formed data.
            //
            String IdString = Request.QueryString[KEY_ID].ToString();
            
            if ( IdString != String.Empty )
            {
                Id = Int32.Parse(IdString);
            }
            
            ApplicationAssert.CheckCondition( Id >= 0, "Invalid Item Id Number", ApplicationAssert.LineNumber);
            
            return true;
        }