DataTable 转 Entity

/// <summary>
/// DataTransfer 的摘要说明
/// </summary>
public static class DataTransfer
{
    /// <summary>
    /// datatable to list
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="dt"></param>
    /// <returns></returns>
    public static List<T> ToList<T>(DataTable dt)
    {
        List<T> list = new List<T>();
        if (dt == null) return list;
        if (dt.Rows.Count < 1) return list;
        DataTableEntityBuilder<T> eblist = DataTableEntityBuilder<T>.CreateBuilder(dt.Rows[0]);
        foreach (DataRow info in dt.Rows)
            list.Add(eblist.Build(info));
        dt.Dispose();
        dt = null;
        return list;
    }

    /// <summary>
    /// builder
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class DataTableEntityBuilder<T>
    {
        private static readonly MethodInfo getValueMethod = typeof(DataRow).GetMethod("get_Item", new Type[] { typeof(int) });
        private static readonly MethodInfo isDBNullMethod = typeof(DataRow).GetMethod("IsNull", new Type[] { typeof(int) });
        private delegate T Load(DataRow dataRecord);

        private Load handler;
        private DataTableEntityBuilder() { }

        public T Build(DataRow dataRecord)
        {
            return handler(dataRecord);
        }

        public static DataTableEntityBuilder<T> CreateBuilder(DataRow dataRow)
        {
            DataTableEntityBuilder<T> dynamicBuilder = new DataTableEntityBuilder<T>();
            DynamicMethod method = new DynamicMethod("DynamicCreateEntity", typeof(T), new Type[] { typeof(DataRow) }, typeof(T), true);
            ILGenerator generator = method.GetILGenerator();
            LocalBuilder result = generator.DeclareLocal(typeof(T));
            generator.Emit(OpCodes.Newobj, typeof(T).GetConstructor(Type.EmptyTypes));
            generator.Emit(OpCodes.Stloc, result);

            for (int index = 0; index < dataRow.ItemArray.Length; index++)
            {
                PropertyInfo propertyInfo = typeof(T).GetProperty(dataRow.Table.Columns[index].ColumnName);
                Label endIfLabel = generator.DefineLabel();
                if (propertyInfo != null && propertyInfo.GetSetMethod() != null)
                {
                    generator.Emit(OpCodes.Ldarg_0);
                    generator.Emit(OpCodes.Ldc_I4, index);
                    generator.Emit(OpCodes.Callvirt, isDBNullMethod);
                    generator.Emit(OpCodes.Brtrue, endIfLabel);
                    generator.Emit(OpCodes.Ldloc, result);
                    generator.Emit(OpCodes.Ldarg_0);
                    generator.Emit(OpCodes.Ldc_I4, index);
                    generator.Emit(OpCodes.Callvirt, getValueMethod);
                    generator.Emit(OpCodes.Unbox_Any, propertyInfo.PropertyType);
                    generator.Emit(OpCodes.Callvirt, propertyInfo.GetSetMethod());
                    generator.MarkLabel(endIfLabel);
                }
            }
            generator.Emit(OpCodes.Ldloc, result);
            generator.Emit(OpCodes.Ret);
            dynamicBuilder.handler = (Load)method.CreateDelegate(typeof(Load));
            return dynamicBuilder;
        }
    }