List<T> DataSet 转换

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Data;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Text;
using System.Reflection;

public partial class Default2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}
/// <summary>
/// 集合装换DataSet
/// </summary>
/// <param name="list">集合</param>
/// <returns></returns>
/// 2008-08-01 22:08 HPDV2806
public static DataSet ToDataSet(IList p_List)
{
DataSet result = new DataSet();
DataTable _DataTable = new DataTable();
if (p_List.Count > 0)
{
PropertyInfo[] propertys = p_List[0].GetType().GetProperties();
foreach (PropertyInfo pi in propertys)
{
_DataTable.Columns.Add(pi.Name, pi.PropertyType);//columnName Type
}

for (int i = 0; i < p_List.Count; i++)
{
ArrayList tempList = new ArrayList();    //一行数据的数组
foreach (PropertyInfo pi in propertys)
{
object obj = pi.GetValue(p_List[i], null);//p_List[i]是集合中的某一个对象，GetValue 返回其属性值
tempList.Add(obj);
}
object[] array = tempList.ToArray();
_DataTable.LoadDataRow(array, true); //LoadDataRow 查找和更新特定行。 如果找不到任何匹配行，则使用给定值创建新行
}
}
result.Tables.Add(_DataTable);
return result;
}

/// <summary>
/// 泛型集合转换DataSet
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="list">泛型集合</param>
/// <returns></returns>
/// 2008-08-01 22:43 HPDV2806
public static DataSet ToDataSet<T>(IList<T> list)
{
return ToDataSet<T>(list, null);
}

/// <summary>
/// 泛型集合转换DataSet
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="p_List">泛型集合</param>
/// <param name="p_PropertyName">待转换属性名数组(null时，表中字段全部转换，有数组时，只转换数组中和表字段都有的字段)</param>
/// <returns></returns>
/// 2008-08-01 22:44 HPDV2806
public static DataSet ToDataSet<T>(IList<T> p_List, params string[] p_PropertyName)
{
List<string> propertyNameList = new List<string>();
if (p_PropertyName != null)
propertyNameList.AddRange(p_PropertyName); //AddRange 向……末尾，添加数组

DataSet result = new DataSet();
DataTable _DataTable = new DataTable();
if (p_List.Count > 0)
{
PropertyInfo[] propertys = p_List[0].GetType().GetProperties();
foreach (PropertyInfo pi in propertys)
{
if (propertyNameList.Count == 0)
{
// 没有指定属性的情况下全部属性都要转换
_DataTable.Columns.Add(pi.Name, pi.PropertyType);
}
else
{
if (propertyNameList.Contains(pi.Name))
_DataTable.Columns.Add(pi.Name, pi.PropertyType);
}
}

for (int i = 0; i < p_List.Count; i++)
{
ArrayList tempList = new ArrayList();
foreach (PropertyInfo pi in propertys)
{
if (propertyNameList.Count == 0)
{
object obj = pi.GetValue(p_List[i], null);
tempList.Add(obj);
}
else
{
if (propertyNameList.Contains(pi.Name))
{
object obj = pi.GetValue(p_List[i], null);
tempList.Add(obj);
}
}
}
object[] array = tempList.ToArray();
_DataTable.LoadDataRow(array, true);
}
}
result.Tables.Add(_DataTable);
return result;
}

/// <summary>
/// DataSet装换为泛型集合
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="p_DataSet">DataSet</param>
/// <param name="p_TableIndex">待转换数据表索引</param>
/// <returns></returns>
/// 2008-08-01 22:46 HPDV2806
public static IList<T> DataSetToIList<T>(DataSet p_DataSet, int p_TableIndex)
{
if (p_DataSet == null || p_DataSet.Tables.Count < 0)
return null;
if (p_TableIndex > p_DataSet.Tables.Count - 1)
return null;
if (p_TableIndex < 0)
p_TableIndex = 0;

DataTable p_Data = p_DataSet.Tables[p_TableIndex];
// 返回值初始化
IList<T> result = new List<T>();
for (int i = 0; i < p_Data.Rows.Count; i++)
{
T _t = (T)Activator.CreateInstance(typeof(T));//Activator.CreateInstrance C#在类工厂中动态创建类的实例
PropertyInfo[] propertys = _t.GetType().GetProperties();
foreach (PropertyInfo pi in propertys)
{
for (int j = 0; j < p_Data.Columns.Count; j++)
{
// 属性与字段名称一致的进行赋值
if (pi.Name.Equals(p_Data.Columns[j].ColumnName))
{
// 数据库NULL值单独处理
if (p_Data.Rows[i][j] != DBNull.Value)
pi.SetValue(_t, p_Data.Rows[i][j], null);  //SetValue 将给定对象的属性值设置为给定值。
else
pi.SetValue(_t, null, null);
break;
}
}
}
result.Add(_t);
}
return result;
}

/// <summary>
/// DataSet装换为泛型集合
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="p_DataSet">DataSet</param>
/// <param name="p_TableName">待转换数据表名称</param>
/// <returns></returns>
/// 2008-08-01 22:47 HPDV2806
public static IList<T> DataSetToIList<T>(DataSet p_DataSet, string p_TableName)
{
int _TableIndex = 0;
if (p_DataSet == null || p_DataSet.Tables.Count < 0)
return null;
if (string.IsNullOrEmpty(p_TableName))
return null;
for (int i = 0; i < p_DataSet.Tables.Count; i++)
{
// 获取Table名称在Tables集合中的索引值
if (p_DataSet.Tables[i].TableName.Equals(p_TableName))
{
_TableIndex = i;
break;
}
}
return DataSetToIList<T>(p_DataSet, _TableIndex);
}
}