c# Dictionary 相关扩展

DictionaryExtend.cs

using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;

namespace iCTR.WeiXin.Common.Extensions
{
    /// <summary>
    /// 字典类扩展
    /// </summary>
    public static class DictionaryExtend
    {
        /// <summary>
        /// 根据OrderedDictionary类型的value获取key
        /// </summary>
        /// <typeparam name="T1">key的类型</typeparam>
        /// <typeparam name="T2">value的类型</typeparam>
        /// <param name="od">OrderedDictionary对象</param>
        /// <param name="value">value</param>
        /// <returns>key的值，如果没有则返回零值</returns>
        public static T1 GetKeyByValue<T1,T2>(this OrderedDictionary od, T2 value)
        {
            foreach (DictionaryEntry o in od)
            {
                // 比较两个参数是否相等
                if (EqualityComparer<T2>.Default.Equals((T2)o.Value,value))
                {
                    return (T1) o.Key;
                }
            }
            return default(T1);
        }

        /// <summary>
        /// 根据索引获取字典的一项
        /// </summary>
        /// <param name="od">有序字典</param>
        /// <param name="i">索引</param>
        /// <returns>字典项</returns>
        public static DictionaryEntry GetItemByIndex(this OrderedDictionary od, int i)
        {
            var j = 0;
            foreach (DictionaryEntry entry in od)
            {
                if (i == j++)
                {
                    return entry;
                }
            }
            return new DictionaryEntry();
        }
    }
}