using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;namespace Common.Unit
{public static class ListHelper{/// <summary>/// 将List转换成String/// </summary>/// <param name="list">List对象</param>/// <returns></returns>public static string SeperateToString(this IEnumerable<int> list){return SeperateToString(list, ",");}/// <summary>/// 将List转换成String/// </summary>/// <param name="list">List对象</param>/// <param name="seperate">分隔符</param>/// <returns></returns>public static string SeperateToString(this IEnumerable<int> list, string seperate){string str = "";if (list == null || list.Count() == 0)return str;foreach (int i in list){str += seperate + i;}return str.Substring(seperate.Length);}/// <summary>/// 将List转换成String/// </summary>/// <param name="list">List对象</param>/// <returns></returns>public static string SeperateToString(this IEnumerable<string> list){return SeperateToString(list, ",");}/// <summary>/// 将List转换成String/// </summary>/// <param name="list">List对象</param>/// <returns></returns>public static string SeperateToString(this IEnumerable<string> list, bool removeEmpty){return SeperateToString(list, ",", removeEmpty);}/// <summary>/// 将List转换成String/// </summary>/// <param name="list">List对象</param>/// <param name="seperate">分隔符</param>/// <returns></returns>public static string SeperateToString(this IEnumerable<string> list, string seperate){return SeperateToString(list, seperate, false);}/// <summary>/// 将List转换成String/// </summary>/// <param name="list">List对象</param>/// <param name="seperate">分隔符</param>/// <param name="removeEmpty">移除空字符</param>/// <returns></returns>public static string SeperateToString(this IEnumerable<string> list, string seperate, bool removeEmpty){string str = "";if (list == null || list.Count() == 0)return str;foreach (string s in list){if (removeEmpty && string.IsNullOrEmpty(s))continue;str += seperate + s;}if (str.Length > 0)str = str.Substring(seperate.Length);return str;}/// <summary>/// 扩展distinct 方法 调用方式lst = lst.Distinct((x, y) => x.ID==y.ID ).ToList();/// </summary>/// <typeparam name="TSource"></typeparam>/// <param name="list"></param>/// <param name="dele"></param>/// <returns></returns>public static IEnumerable<TSource> Distinct<TSource>(this IEnumerable<TSource> list, EqualsComparer<TSource> dele){return list.Distinct(new Compare<TSource>(dele));}/// <summary>/// 扩展distinct 方法 调用方式 lst = lst.Distinct(p => p.ID).ToList();/// </summary>/// <typeparam name="T"></typeparam>/// <typeparam name="V"></typeparam>/// <param name="source"></param>/// <param name="keySelector"></param>/// <returns></returns>public static IEnumerable<T> Distinct<T, V>(this IEnumerable<T> source, Func<T, V> keySelector){                        return source.Distinct(new CommonEqualityComparer<T, V>(keySelector));}  static void test(){List<int> list = new List<int>();list.Add(1);list.Add(2);list.Add(3);Console.WriteLine(list.SeperateToString(","));List<string> list2 = new List<string>();list2.Add("1");list2.Add("2");list2.Add("3");Console.WriteLine(list2.SeperateToString(",", false));}}#region 实现Distinct IEqualityComparer 接口public delegate bool EqualsComparer<T>(T x, T y);public class Compare<T> : IEqualityComparer<T>{private EqualsComparer<T> _equalsComparer;public Compare(EqualsComparer<T> equalsComparer){this._equalsComparer = equalsComparer;}public bool Equals(T x, T y){if (null != this._equalsComparer)return this._equalsComparer(x, y);elsereturn false;}public int GetHashCode(T obj){return obj.ToString().GetHashCode();}}public class CommonEqualityComparer<T, V> : IEqualityComparer<T>{private Func<T, V> keySelector;public CommonEqualityComparer(Func<T, V> keySelector){this.keySelector = keySelector;}public bool Equals(T x, T y){return EqualityComparer<V>.Default.Equals(keySelector(x), keySelector(y));}public int GetHashCode(T obj){return EqualityComparer<V>.Default.GetHashCode(keySelector(obj));}}
#endregion
}