C#扩展方法试用

以前某面试题要求给string扩展一个IsNotNullOrEmpty的方法。当时没有想到合适的办法。后来发现3.0以后加了个扩展方法的语法糖。现收集了几位园友的某些实际应用，自己也试试写了几个方法。大家用的着的，尽管Copy啊。  如果你觉得代码很熟悉，是你写的我在此谢过了。

 

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

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            //简写 foreach测试
            string[] temp = new string[] {"White","Red","Green"};
            temp.Each(str => Console.WriteLine(str));

            IList<Employee> empList = new List<Employee> { 
                new Employee{EmpNo="001",Name="小李"},
                new Employee{EmpNo="002",Name="小赵"},
                new Employee{EmpNo="003",Name="小王"}
            };
            //获取某个List的每个Item的某个属性，返回为一个数组
            empList.ToStringArray("Name").Each(str => Console.WriteLine(str));

            Console.WriteLine(DateTime.Now.TruncateTime().ToString());
            decimal amount = 9810298.36M;
            Console.WriteLine(amount.ToRMB());           
        }
    }

    public class Employee
    {
        public string EmpNo
        {
            get;
            set;
        }

        public string Name
        {
            get;
            set;
        }
    }
}

 

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

namespace WinComman
{
    ///<summary>
    /// C#扩展类
    ///</summary>
    public static class GhoughShawExtClass
    {
        ///<summary>
        /// 按指定属性返回T的指定属性ToString()后的数组
        ///</summary>
        ///<typeparam name="T"></typeparam>
        ///<param name="list">集合</param>
        ///<param name="propertyName">属性，需要完全匹配大小写</param>
        ///<returns></returns>
        public static string[] ToStringArray<T>(this IEnumerable<T> list, string propertyName)
        {
            string[] result = new string[list.Count()];
            int i = 0;
            foreach (var item in list)
            {
                Type t = item.GetType();
                var piList = t.GetProperties();
                var pi = piList.Where(p => p.Name.Equals(propertyName)).FirstOrDefault();
                if (pi != null)
                {
                    result[i] = pi.GetValue(item, null).ToString();
                    i++;
                }
                else
                {
                    break;
                    throw new Exception(string.Format("对象'{0}',不存在'{1}'属性！", t.Name, propertyName));
                };

            }
            return result;
        } 

   
        ///<summary>
        /// 日期时间型取整，舍去时间
        ///</summary>
        ///<param name="value"></param>
        ///<returns></returns>
        public static DateTime TruncateTime(this DateTime value)
        {
            return DateTime.Parse(value.ToLongDateString() + " 00:00:00");
        }

        ///<summary>
        /// 货币转人民币大写
        ///</summary>
        ///<param name="amountValue"></param>
        ///<returns></returns>
        public static string ToRMB(this decimal amountValue)
        {
            var money = new Money(amountValue);
            return money.ToString();
        }

        ///<summary>
        /// 货币转人民币大写
        ///</summary>
        ///<param name="amountValue"></param>
        ///<returns></returns>
        public static string ToRMB(this double amountValue)
        {
            var money = new Money(Convert.ToDecimal(amountValue));
            return money.ToString();
        }

        #region 简化流程型语句 如Foreach For  非本人代码，取自博客园某牛人(忘记了，不好意思)，在此谢过

        ///<summary>
        /// 简化Foreach的写法
        ///</summary>
        ///<typeparam name="TSource"></typeparam>
        ///<param name="obj"></param>
        public delegate void EachMethod<TSource>(TSource obj);
        public static void Each<TSource>(this IEnumerable<TSource> source, EachMethod<TSource> method)
        {
            foreach (TSource obj in source)
            {
                method(obj);
            }
        }

        ///<summary>
        /// 简化在循环内部，Item满足某个条件时，执行某个方法的写法
        ///</summary>
        ///<typeparam name="TSource"></typeparam>
        ///<param name="source"></param>
        ///<param name="selector"></param>
        ///<param name="method"></param>
        public static void If<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> selector, EachMethod<TSource> method)
        {
            foreach (TSource obj in source)
            {
                if (selector(obj))
                    method(obj);
            }
        }

        ///<summary>
        /// 简化For的写法
        ///</summary>
        ///<param name="max"></param>
        ///<param name="method"></param>
        public static void For(this int max, Func<int, bool> method)
        {
            for (int i = 0; i < max; i++)
            {
                if (!method(i))
                {
                    break;
                }
            }
        }

        ///<summary>
        /// 简化For的写法 Down To 
        ///</summary>
        ///<param name="max"></param>
        ///<param name="method"></param>
        public static void DownFor(this int max, int min, Func<int, bool> method)
        {
            for (int i = max; i > min; i--)
            {
                if (!method(i))
                {
                    break;
                }
            }
        }
        #endregion
    }

    ///<summary>
    /// dudu 写的Wcf Client 扩展类,这个办法我试用过了。果然是享受
    ///</summary>
    public class WcfClient
    {
        public static TReturn UseService<TChannel, TReturn>(Func<TChannel, TReturn> func)
        {
            var chanFactory = new ChannelFactory<TChannel>("*");
            TChannel channel = chanFactory.CreateChannel();
            TReturn result = func(channel);
            try
            {
                ((IClientChannel)channel).Close();
            }
            catch
            {
                ((IClientChannel)channel).Abort();
            }
            return result;
        }
    }

    ///<summary>
    /// 伍华聪的WCF client 扩展
    ///</summary>
    public static class WcfExtensions
    {
        public static void Using<T>(this T client, Action<T> work) where T : ICommunicationObject
        {
            try
            {
                work(client);
                client.Close();
            }
            catch (CommunicationException ex)
            {
                client.Abort();               
            }
            catch (TimeoutException ex)
            {
                client.Abort();              
            }
            catch (Exception ex)
            {
                client.Abort();              
            }
        }
    }

    public class Money
    {
        public string Yuan = "元";                        // “元”，可以改为“圆”、“卢布”之类
        public string Jiao = "角";                        // “角”，可以改为“拾”
        public string Fen = "分";                        // “分”，可以改为“美分”之类
        static string Digit = "零壹贰叁肆伍陆柒捌玖";      // 大写数字
        bool isAllZero = true;                        // 片段内是否全零
        bool isPreZero = true;                        // 低一位数字是否是零
        bool Overflow = false;                       // 溢出标志
        long money100;                                   // 金额*100，即以“分”为单位的金额
        long value;                                      // money100的绝对值
        StringBuilder sb = new StringBuilder();         // 大写金额字符串，逆序
        // 只读属性: "零元"
        public string ZeroString
        {
            get { return Digit[0] + Yuan; }
        }
        // 构造函数
        public Money(decimal money)
        {
            try { money100 = (long)(money * 100m); }
            catch { Overflow = true; }
            if (money100 == long.MinValue) Overflow = true;
        }
        // 重载 ToString() 方法，返回大写金额字符串
        public override string ToString()
        {
            if (Overflow) return "金额超出范围";
            if (money100 == 0) return ZeroString;
            string[] Unit = { Yuan, "万", "亿", "万", "亿亿" };
            value = System.Math.Abs(money100);
            ParseSection(true);
            for (int i = 0; i < Unit.Length && value > 0; i++)
            {
                if (isPreZero && !isAllZero) sb.Append(Digit[0]);
                if (i == 4 && sb.ToString().EndsWith(Unit[2]))
                    sb.Remove(sb.Length - Unit[2].Length, Unit[2].Length);
                sb.Append(Unit[i]);
                ParseSection(false);
                if ((i % 2) == 1 && isAllZero)
                    sb.Remove(sb.Length - Unit[i].Length, Unit[i].Length);
            }
            if (money100 < 0) sb.Append("负");
            return Reverse();
        }
        // 解析“片段”: “角分(2位)”或“万以内的一段(4位)”
        void ParseSection(bool isJiaoFen)
        {
            string[] Unit = isJiaoFen ?
              new string[] { Fen, Jiao } :
              new string[] { "", "拾", "佰", "仟" };
            isAllZero = true;
            for (int i = 0; i < Unit.Length && value > 0; i++)
            {
                int d = (int)(value % 10);
                if (d != 0)
                {
                    if (isPreZero && !isAllZero) sb.Append(Digit[0]);
                    sb.AppendFormat("{0}{1}", Unit[i], Digit[d]);
                    isAllZero = false;
                }
                isPreZero = (d == 0);
                value /= 10;
            }
        }
        // 反转字符串
        string Reverse()
        {
            StringBuilder sbReversed = new StringBuilder();
            for (int i = sb.Length - 1; i >= 0; i--)
                sbReversed.Append(sb[i]);
            return sbReversed.ToString();
        }
    }
}