List转换为DataTable

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Reflection;
using System.Collections;

namespace Console4
{
    public class DataTableExtensions
    {
        /// <summary>
        /// List转为一个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>();
            //获取反射的入口
            Type type = typeof(T);
            DataTable dt = new DataTable();
            //把所有的public属性加入到集合中,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;
        }


        /// <summary>
        /// DataTable 转为 List 集合
        /// </summary>
        /// <typeparam name="T">类型</typeparam>
        /// <param name="dt"></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);
            //获取TResult的所有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) != -1) 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 obj = new T();
                //找到对应的数据,并赋值
                prList.ForEach(p => { if (row[p.Name] != DBNull.Value) p.SetValue(obj, row[p.Name], null); });
                //放入到返回的集合中
                obList.Add(obj);
            }
            return obList;
        }

        /// <summary>
        /// 将集合类转为DataTable
        /// </summary>
        /// <param name="list">集合</param>
        /// <returns></returns>
        public static DataTable ToDataTableRow(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);
                }
                for (int i = 0; i < list.Count; i++)
                {
                    ArrayList tempList = new ArrayList();
                    foreach (PropertyInfo pi in propertys)
                    {
                        object obj = pi.GetValue(list[i], null);
                        tempList.Add(obj);
                    }
                    object[] array = tempList.ToArray();
                    result.LoadDataRow(array, true);
                }
            }

            return result;
        }


        /// <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)
        {
            DataTable result = new DataTable();

            List<string> propertyNameList = new List<string>();
            if (propertyName != null)
            {
                propertyNameList.AddRange(propertyName);
            }

            if (list.Count > 0)
            {
                PropertyInfo[] properties = list[0].GetType().GetProperties();
                foreach (PropertyInfo pi in properties)
                {
                    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 properties)
                    {
                        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;
        }

    }
}

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