Linq排序有很多方法，好多都是关于静态排序，而静态排序相对来说比较简单，也比较容易实现，我这里需要一个动态排序。就是按字符串形式传递需要排序的列名,和"asc","desc"。这需要我们动态构建lamdba表达式,下面来看写的一个扩展类，部分源码参考了网上，还有的AsQueryable() 这个方法是看了http://blog.csdn.net/fhzh520/article/details/6062447 这篇文章才知道的..以前总是IEnumerable强转IQueryable但有时候失败.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;

namespace Blogs.DAL
{
    public static class QueryableExtensions
    {
        public static IEnumerableOrderByEx(this IEnumerablequeryable, string propertyName)
        {
            return QueryableHelper.OrderBy(queryable, propertyName, false);
        }
        public static IEnumerableOrderByEx(this IEnumerablequeryable, string propertyName, bool desc)
        {
            return QueryableHelper.OrderBy(queryable, propertyName, desc);
        }
        private static class QueryableHelper{
            private static Dictionary cache = new Dictionary();
            public static IEnumerableOrderBy(IEnumerablequeryable, string propertyName, bool desc)
            {
                dynamic keySelector = GetLambdaExpression(propertyName);

                IQueryablequery = queryable.AsQueryable();
                return desc ? Queryable.OrderByDescending(query, keySelector) : Queryable.OrderBy(query, keySelector);
            }
            private static LambdaExpression GetLambdaExpression(string propertyName)
            {
                if (cache.ContainsKey(propertyName)) return cache[propertyName];
                var param = Expression.Parameter(typeof(T));
                var body = Expression.Property(param, propertyName);
                var keySelector = Expression.Lambda(body, param);
                cache[propertyName] = keySelector;
                return keySelector;
            }
        }
    }
}

IEnumerablelist;

//省略获取list

//升序

list.OrderByEx("排序列");

//倒序

list.OrderByEx("排序列",true);