C# List去重DistinctBy扩展

list 去重扩展：

 public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
        {
            HashSet<TKey> keys = new HashSet<TKey>();
            foreach (TSource element in source)
                if (keys.Add(keySelector(element)))
                    yield return element;
        }

　　比较两个集合

public static bool CompareType<T>(T oneT, T twoT)
        {
            bool result = true;//两个类型作比较时使用,如果有不一样的就false
            Type typeOne = oneT.GetType();
            Type typeTwo = twoT.GetType();
            //如果两个T类型不一样  就不作比较
            if (!typeOne.Equals(typeTwo)) { return false; }
            PropertyInfo[] pisOne = typeOne.GetProperties(); //获取所有公共属性(Public)
            PropertyInfo[] pisTwo = typeTwo.GetProperties();
            //如果长度为0返回false
            if (pisOne.Length <= 0 || pisTwo.Length <= 0)
            {
                return false;
            }
            //如果长度不一样，返回false
            if (!(pisOne.Length.Equals(pisTwo.Length))) { return false; }
            //遍历两个T类型，遍历属性，并作比较
            for (int i = 0; i < pisOne.Length; i++)
            {
                //获取属性名
                string oneName = pisOne[i].Name;
                string twoName = pisTwo[i].Name;
                //获取属性的值
                object oneValue = pisOne[i].GetValue(oneT, null);
                object twoValue = pisTwo[i].GetValue(twoT, null);
                //比较,只比较值类型
                if ((pisOne[i].PropertyType.IsValueType || pisOne[i].PropertyType.Name.StartsWith("String")) && (pisTwo[i].PropertyType.IsValueType || pisTwo[i].PropertyType.Name.StartsWith("String")))
                {
                    if (oneName.Equals(twoName))
                    {
                        if (oneValue == null)
                        {
                            if (twoValue != null)
                            {
                                result = false;
                                break; //如果有不一样的就退出循环
                            }
                        }
                        else if (oneValue != null)
                        {
                            if (twoValue != null)
                            {
                                if (!oneValue.Equals(twoValue))
                                {
                                    result = false;
                                    break; //如果有不一样的就退出循环
                                }
                            }
                            else if (twoValue == null)
                            {
                                result = false;
                                break; //如果有不一样的就退出循环
                            }
                        }
                    }
                    else
                    {
                        result = false;
                        break;
                    }
                }
                else
                {
                    //如果对象中的属性是实体类对象，递归遍历比较
                    bool b = CompareType(oneValue, twoValue);
                    if (!b) { result = b; break; }
                }
            }
            return result;
        }

　　这种方法更快点：

     public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
        {
            HashSet<TKey> keys = new HashSet<TKey>();
            foreach (TSource element in source)
                if (keys.Add(keySelector(element)))
                    yield return element;
        }