DataSet和List<T> 泛型之间互相转换 (转载, 作者写的很好)

/DataSet与泛型集合间的互相转换

//利用反射机制将DataTable的字段与自定义类型的公开属性互相赋值。

//注意：从DataSet到IList<T>的转换，自定义类型的公开属性必须与DataTable中的字段名称

//一致，才能到达想要的结果。建议DataTable的定义从数据库来，自定义类型用O/R Mapping的方式获得。

 

//代码说明

 

 

 

/// <summary>

/// 泛型集合与DataSet互相转换

/// </summary>

using System.Data;

using System.Reflection;

using System.Collections;

using System.Collections.Generic;

using System;

public class IListDataSet

{

 

    /// <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);

            }

 

            for (int i = 0; i < p_List.Count; i++)

            {

                ArrayList tempList = new ArrayList();

                foreach (PropertyInfo pi in propertys)

                {

                    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>

    /// 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</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);

 

        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 j = 0; j < p_Data.Rows.Count; j++)

        {

            T _t = (T)Activator.CreateInstance(typeof(T));

            PropertyInfo[] propertys = _t.GetType().GetProperties();

            foreach (PropertyInfo pi in propertys)

            {

                for (int i = 0; i < p_Data.Columns.Count; i++)

                {

                    // 属性与字段名称一致的进行赋值

                    if (pi.Name.Equals(p_Data.Columns[i].ColumnName))

                    {

                        // 数据库NULL值单独处理

                        if (p_Data.Rows[j][i] != DBNull.Value)

                            pi.SetValue(_t, p_Data.Rows[j][i], null);

                        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);

    }

}

 

 

/*****************

使用范围

 

1. 可以用在业务层中数据获取，获取DataSet的同时也可以转为IList集合为调用者所使用。

 

2. 在WebServices中传输自定义类型使用，即传递参数都用DataSet类型（WebServices直接支持的数据类型），在使用前将其转换为IList来使用。

 * ******************************/