List<T> 和DataTable的相互转换

　　我用的将集合类转换为DataTable 的方法

        /// <summary>
        /// 将集合类转换成DataTable
        /// </summary>
        /// <param name="list">集合</param>
        /// <returns></returns>
        private static DataTable ToDataTableTow(IList list)
        {
            DataTable result = new DataTable();
            if (list.Count > )
            {
                PropertyInfo[] propertys = list[].GetType().GetProperties();

                foreach (PropertyInfo pi in propertys)
                {
                    result.Columns.Add(pi.Name, pi.PropertyType);
                }
                foreach (object t in list)
                {
                    ArrayList tempList = new ArrayList();
                    foreach (PropertyInfo pi in propertys)
                    {
                        object obj = pi.GetValue(t, null);
                        tempList.Add(obj);
                    }
                    object[] array = tempList.ToArray();
                    result.LoadDataRow(array, true);
                }
            }
            return result;
        }

将DataTable转换为List<T>

　　

    /// <summary>
    /// DataTable 转换为List 集合
    /// </summary>
    /// <typeparam name="TResult">类型</typeparam>
    /// <param name="dt">DataTable</param>
    /// <returns></returns>
    public static List<T> ToList<T>(this DataTable dt) where T : class, new()
    {
        //创建一个属性的列表
        List<PropertyInfo> prlist = new List<PropertyInfo>();
        //获取TResult的类型实例  反射的入口    

        Type t = typeof(T);  

        //获得TResult 的所有的Public 属性 并找出TResult属性和DataTable的列名称相同的属性(PropertyInfo) 并加入到属性列表
        Array.ForEach<PropertyInfo>(t.GetProperties(), p => { if (dt.Columns.IndexOf(p.Name) != -) prlist.Add(p); });  

        //创建返回的集合    

        List<T> oblist = new List<T>();  

        foreach (DataRow row in dt.Rows)
        {
            //创建TResult的实例
            T ob = new T();
            //找到对应的数据  并赋值
            prlist.ForEach(p => { if (row[p.Name] != DBNull.Value) p.SetValue(ob, row[p.Name], null); });
            //放入到返回的集合中.
            oblist.Add(ob);
        }
        return oblist;
    }  

其它的实现方式

　　

    /// <summary>
    /// 转化一个DataTable
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="list"></param>
    /// <returns></returns>
    public static DataTable ToDataTable<T>(this IEnumerable<T> list)
    {
        //创建属性的集合
        List<PropertyInfo> pList = new List<PropertyInfo>();
        //获得反射的入口
        Type type = typeof(T);
        DataTable dt = new DataTable();
        //把所有的public属性加入到集合 并添加DataTable的列
        Array.ForEach<PropertyInfo>(type.GetProperties(), p => { pList.Add(p); dt.Columns.Add(p.Name, p.PropertyType); });
        foreach (var item in list)
        {
            //创建一个DataRow实例
            DataRow row = dt.NewRow();
            //给row 赋值
            pList.ForEach(p => row[p.Name] = p.GetValue(item, null));
            //加入到DataTable
            dt.Rows.Add(row);
        }
        return dt;
    } 

返回指定的列

　　

 /// <summary>
    /// 将泛型集合类转换成DataTable    

    /// </summary>
    /// <typeparam name="T">集合项类型</typeparam>    

    /// <param name="list">集合</param>
    /// <returns>数据集(表)</returns>
    public static DataTable ToDataTable<T>(IList<T> list)
    {
        return ToDataTable<T>(list, null);  

    }  

    /**/  

    /// <summary>
    /// 将泛型集合类转换成DataTable
    /// </summary>
    /// <typeparam name="T">集合项类型</typeparam>
    /// <param name="list">集合</param>
    /// <param name="propertyName">需要返回的列的列名</param>
    /// <returns>数据集(表)</returns>
    public static DataTable ToDataTable<T>(IList<T> list, params string[] propertyName)
    {
        List<string> propertyNameList = new List<string>();
        if (propertyName != null)
            propertyNameList.AddRange(propertyName);
        DataTable result = new DataTable();
        if (list.Count > )
        {
            PropertyInfo[] propertys = list[].GetType().GetProperties();
            foreach (PropertyInfo pi in propertys)
            {
                if (propertyNameList.Count == )
                {
                    result.Columns.Add(pi.Name, pi.PropertyType);
                }
                else
                {
                    if (propertyNameList.Contains(pi.Name))
                        result.Columns.Add(pi.Name, pi.PropertyType);
                }
            }  

            for (int i = ; i < list.Count; i++)
            {
                ArrayList tempList = new ArrayList();
                foreach (PropertyInfo pi in propertys)
                {
                    if (propertyNameList.Count == )
                    {
                        object obj = pi.GetValue(list[i], null);
                        tempList.Add(obj);
                    }
                    else
                    {
                        if (propertyNameList.Contains(pi.Name))
                        {
                            object obj = pi.GetValue(list[i], null);
                            tempList.Add(obj);
                        }
                    }
                }
                object[] array = tempList.ToArray();
                result.LoadDataRow(array, true);
            }
        }
        return result;
    }
}