linq分页扩展

public static List<T> ToPagedList<T>(this IEnumerable<T> allItems, int pageIndex, int pageSize, Expression<Func<T, int>> keySelector)
        {
            var itemList = allItems.Skip(pageSize * (pageIndex - 1)).Take(pageSize).ToList();
            return itemList;
        }
        public static List<T> ToPagedList<T>(this IEnumerable<T> allItems, int pageIndex, int pageSize, Expression<Func<T, bool>> keySelector)
        {
            var itemList = allItems.Skip(pageSize * (pageIndex - 1)).Take(pageSize).ToList();
            return itemList;
        }
        public static List<T> ToPagedList<T>(this IEnumerable<T> allItems, int pageIndex, int pageSize, Expression<Func<T, string>> keySelector)
        {
            var itemList = allItems.Skip(pageSize * (pageIndex - 1)).Take(pageSize).ToList();
            return itemList;
        }
        public static List<T> ToPagedList<T>(this IEnumerable<T> allItems, int pageIndex, int pageSize, Expression<Func<T, DateTime>> keySelector)
        {
            var itemList = allItems.Skip(pageSize * (pageIndex - 1)).Take(pageSize).ToList();
            return itemList;
        }
        public static List<T> ToPagedList<T>(this IQueryable<T> allItems, int pageIndex, int pageSize, Expression<Func<T,int>> keySelector)
        {
            var itemList = allItems.OrderBy(keySelector).Skip(pageSize * (pageIndex - 1)).Take(pageSize).ToList();
            return itemList;
        }
        public static List<T> ToPagedList<T>(this IQueryable<T> allItems, int pageIndex, int pageSize, Expression<Func<T, bool>> keySelector)
        {
            var itemList = allItems.OrderBy(keySelector).Skip(pageSize * (pageIndex - 1)).Take(pageSize).ToList();
            return itemList;
        }
        public static List<T> ToPagedList<T>(this IQueryable<T> allItems, int pageIndex, int pageSize, Expression<Func<T, string>> keySelector)
        {
            var itemList = allItems.OrderBy(keySelector).Skip(pageSize * (pageIndex - 1)).Take(pageSize).ToList();
            return itemList;
        }
        public static List<T> ToPagedList<T>(this IQueryable<T> allItems, int pageIndex, int pageSize, Expression<Func<T, DateTime>> keySelector)
        {
            var itemList = allItems.OrderBy(keySelector).Skip(pageSize * (pageIndex - 1)).Take(pageSize).ToList();
            return itemList;
        }