Distinct 条件去重

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ZY.Common
{
   
        public static class CommonHelper
        {
            /// <summary>
            /// 自定义Distinct扩展方法
            /// </summary>
            /// <typeparam name="T">要去重的对象类</typeparam>
            /// <typeparam name="C">自定义去重的字段类型</typeparam>
            /// <param name="source">要去重的对象</param>
            /// <param name="getfield">获取自定义去重字段的委托</param>
            /// <returns></returns>
            public static IEnumerable<T> DistinctBy<T, C>(this IEnumerable<T> source, Func<T, C> getfield)
            {
                return source.Distinct(new Compare<T, C>(getfield));
            }
        }
        public class Compare<T, C> : IEqualityComparer<T>
        {
            private Func<T, C> _getField;
            public Compare(Func<T, C> getfield)
            {
                this._getField = getfield;
            }
            public bool Equals(T x, T y)
            {
                return EqualityComparer<C>.Default.Equals(_getField(x), _getField(y));
            }
            public int GetHashCode(T obj)
            {
                return EqualityComparer<C>.Default.GetHashCode(this._getField(obj));
            }
        }
       
    
}