List<T>的对比

对于类型的对比，linq原来的对比是区分不了的。

对两个list进行查询交集方法。交集，并集的函数是直接用Linq的，这里不再写。

List<T> intersectList = queryList.AsQueryable().Intersect(sqlList, new ListEquality<T>()).ToList();

   public class ListEquality<T> : IEqualityComparer<T> where T : new()
     {

         PropertyInfo[] propertys = typeof(T).GetProperties().Where(p => p.Name != "ParamInfo").Where(p => p.Name != "State").ToArray();

         public bool Equals(T x, T y)
         {
             foreach (var pe in propertys)
             {
                 object o_x = pe.GetValue(x, null);
                 object o_y = pe.GetValue(y, null);
                 if (!object.Equals(o_x, o_y))
                 {
                     return false;
                 }
             }
             return true;
         }

         public int GetHashCode(T obj)
         {
             if (obj == null)
             {
                 return ;
             }
             else
             {
                 return obj.ToString().GetHashCode();
             }
         }
     }

上面的代码明显是根据排除字段来对比的。如果你不想根据字段对比，那就不要排除。

通过主键属性来对比仅仅是主键的类

    public class ListKeyEquality<T> : IEqualityComparer<T> where T : new()
     {

         PropertyInfo[] propertys = typeof(T).GetProperties().Where(p => p.Name != "ParamInfo").Where(p => p.Name != "State").ToArray();
         public bool Equals(T x, T y)
         {
             foreach (var pe in propertys)
             {
                 object[] allAttributes = pe.GetCustomAttributes(false);
                 if (allAttributes.Count() == )
                 {
                     continue;
                 }
                 if ((allAttributes.FirstOrDefault() as GrantAttribute).IsKey)
                 {
                     object o_x = pe.GetValue(x, null);
                     object o_y = pe.GetValue(y, null);
                     if (!object.Equals(o_x, o_y))
                     {
                         return false;
                     }
                 }

             }
             return true;
         }

         public int GetHashCode(T obj)
         {
             if (obj == null)
             {
                 return ;
             }
             else
             {
                 return obj.ToString().GetHashCode();
             }
         }
     }

   public class GrantAttribute : Attribute
     {
         /// <summary>
         /// 是否xml类型
         /// </summary>
         public bool CheckXml { get; set; }
         /// <summary>
         /// 是否主键
         /// </summary>
         public bool IsKey { get; set; }
     }

类的主键属性调用也是很简单

    public class OrderInfo
    {
        /// <summary>
        /// 本系统订单ID
        /// </summary>
        [Grant(IsKey = true)]
        public Guid OrderId { get; set; }
    }