List<T>和DataTable的相互轉換

　　我用的將集合類轉換為DataTable 的方法

        /// <summary>    
        /// 將集合類轉換成DataTable    
        /// </summary>    
        /// <param name="list">集合</param>    
        /// <returns></returns>    
        private static DataTable ToDataTableTow(IList list)
        {
            DataTable result = new DataTable();
            if (list.Count > 0)
            {
                PropertyInfo[] propertys = list[0].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;
        }

將DataTable轉換為List<T>

    /// <summary>    
    /// DataTable 轉換為List 集合    
    /// </summary>    
    /// <typeparam name="TResult">類型</typeparam>    
    /// <param name="dt">DataTable</param>    
    /// <returns></returns>    
    public static List<T> ToList<T>(this DataTable dt) where T : class, new()  
    {  
        //創建一個屬性的列表    
        List<PropertyInfo> prlist = new List<PropertyInfo>();  
        //獲取TResult的類型實例  反射的入口    
  
        Type t = typeof(T);  
  
        //獲得TResult 的所有的Public 屬性 並找出TResult屬性和DataTable的列名稱相同的屬性(PropertyInfo) 並加入到屬性列表     
        Array.ForEach<PropertyInfo>(t.GetProperties(), p => { if (dt.Columns.IndexOf(p.Name) != -1) prlist.Add(p); });  
  
        //創建返回的集合    
  
        List<T> oblist = new List<T>();  
  
        foreach (DataRow row in dt.Rows)  
        {  
            //創建TResult的實例    
            T ob = new T();  
            //找到對應的數據  並賦值    
            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;  
    }  

其它的實現方式

    /// <summary>     
    /// 轉化一個DataTable    
    /// </summary>      
    /// <typeparam name="T"></typeparam>    
    /// <param name="list"></param>    
    /// <returns></returns>    
    public static DataTable ToDataTable<T>(this IEnumerable<T> list)  
    {    
        //創建屬性的集合    
        List<PropertyInfo> pList = new List<PropertyInfo>();  
        //獲得反射的入口    
        Type type = typeof(T);  
        DataTable dt = new DataTable();  
        //把所有的public屬性加入到集合 並添加DataTable的列    
        Array.ForEach<PropertyInfo>(type.GetProperties(), p => { pList.Add(p); dt.Columns.Add(p.Name, p.PropertyType); });  
        foreach (var item in list)  
        {  
            //創建一個DataRow實例    
            DataRow row = dt.NewRow();  
            //給row 賦值    
            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>    
    /// 將泛型集合類轉換成DataTable    
  
    /// </summary>    
    /// <typeparam name="T">集合項類型</typeparam>    
  
    /// <param name="list">集合</param>    
    /// <returns>數據集(表)</returns>    
    public static DataTable ToDataTable<T>(IList<T> list)  
    {  
        return ToDataTable<T>(list, null);  
  
    }  
    
    /**/  
  
    /// <summary>    
    /// 將泛型集合類轉換成DataTable    
    /// </summary>    
    /// <typeparam name="T">集合項類型</typeparam>    
    /// <param name="list">集合</param>    
    /// <param name="propertyName">需要返回的列的列名</param>    
    /// <returns>數據集(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 > 0)  
        {  
            PropertyInfo[] propertys = list[0].GetType().GetProperties();  
            foreach (PropertyInfo pi in propertys)  
            {  
                if (propertyNameList.Count == 0)  
                {  
                    result.Columns.Add(pi.Name, pi.PropertyType);  
                }  
                else  
                {  
                    if (propertyNameList.Contains(pi.Name))  
                        result.Columns.Add(pi.Name, pi.PropertyType);  
                }  
            }  
  
            for (int i = 0; i < list.Count; i++)  
            {  
                ArrayList tempList = new ArrayList();  
                foreach (PropertyInfo pi in propertys)  
                {  
                    if (propertyNameList.Count == 0)  
                    {  
                        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;  
    }  
}