bookList = bookList.Distinct(new DataRowComparer()).ToList(); //去除重复书籍

/// <summary>

/// 自定义书籍比较(去重)

/// </summary>

public class DataRowComparer : IEqualityComparer<BookInfo>

{

    public bool Equals(BookInfo b1, BookInfo b2)

    {

        return (b1.BookId == b2.BookId); //去重

    }

    public int GetHashCode(BookInfo b)

    {

        return b.ToString().GetHashCode();

    }

}

 return list.Distinct(o => o.Id).ToList();//去重

    public static class EnumerableExtender

    {

        public static IEnumerable<TSource> Distinct<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)

        {

            HashSet<TKey> seenKeys = new HashSet<TKey>();

            foreach (TSource element in source)

            {

                var elementValue = keySelector(element);

                if (seenKeys.Add(elementValue))

                {

                    yield return element;

                }

            }

        }

    }

List<string> list = new List<string>();

list.Add("a");

list.Add("a");

list.Add("b");

list.Add("c");

list.Add("b");

list = list.Distinct().ToList();