最开始使用反射一个类型的各个属性，对气进行赋值的代码如下:

public static List
     
       ToList
      
       (IDataReader reader){    //实例化一个List<>泛型集合    List
       
         DataList = new List
        
         ();    PropertyInfo[] properties = typeof(T).GetProperties().Union(typeof(T).BaseType.GetProperties()).ToArray();    while (reader.Read())    {       T RowInstance = Activator.CreateInstance
         
          ();//动态创建数据实体对象       //通过反射取得对象所有的Property       foreach (PropertyInfo Property in properties)       {           try           {               //取得当前数据库字段的顺序               int Ordinal = reader.GetOrdinal(Property.Name);               if (reader.GetValue(Ordinal) != DBNull.Value)               {                    //将DataReader读取出来的数据填充到对象实体的属性里                    Property.SetValue(RowInstance, Convert.ChangeType(reader.GetValue(Ordinal), Property.PropertyType), null);               }           }           catch           {               break;           }      }      DataList.Add(RowInstance);    }    return DataList;}
         
        
       
      
     

以上代码封装一个320条记录、50个字段属性耗时13000豪秒，体验相当差。

后来改用以下这种方式后，性能大幅提升，同样是320条记录、50个字段仅用时17-26毫秒：

public class IDataReaderEntityBuilder
     
          {        private static readonly MethodInfo getValueMethod = typeof(IDataRecord).GetMethod("get_Item", new Type[] { typeof(int) });        private static readonly MethodInfo isDBNullMethod = typeof(IDataRecord).GetMethod("IsDBNull", new Type[] { typeof(int) });        private delegate Entity Load(IDataRecord dataRecord);         private Load handler;        private IDataReaderEntityBuilder() { }         public Entity Build(IDataRecord dataRecord) { return handler(dataRecord); }         public static IDataReaderEntityBuilder
      
        CreateBuilder(IDataRecord dataRecord)        {            IDataReaderEntityBuilder
       
         dynamicBuilder = new IDataReaderEntityBuilder
        
         ();            DynamicMethod method = new DynamicMethod("IDataReaderDynamicCreateEntity", typeof(Entity), new Type[] { typeof(IDataRecord) }, typeof(Entity), true);            ILGenerator generator = method.GetILGenerator();            LocalBuilder result = generator.DeclareLocal(typeof(Entity));            generator.Emit(OpCodes.Newobj, typeof(Entity).GetConstructor(Type.EmptyTypes));            generator.Emit(OpCodes.Stloc, result);             var properties = typeof(Entity).GetProperties();            for (int i = 0; i < dataRecord.FieldCount; i++)            {                PropertyInfo propertyInfo = typeof(Entity).GetProperty(properties.FirstOrDefault(x=>x.Name.ToUpper().Equals(dataRecord.GetName(i)))?.Name);                Label endIfLabel = generator.DefineLabel();                if (propertyInfo != null && propertyInfo.GetSetMethod() != null)                {                    generator.Emit(OpCodes.Ldarg_0);                    generator.Emit(OpCodes.Ldc_I4, i);                    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, i);                    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;        }    }
        
       
      
     

调用方式如下：

public static List
     
       ReaderToEntity
      
       (IDataReader reader){     //实例化一个List<>泛型集合     List
       
         list = new List
        
         ();     var builder = IDataReaderEntityBuilder
         
          .CreateBuilder(reader);     while (reader.Read())     {         var entity = builder.Build(reader);         list.Add(entity);     }     return list;}
         
        
       
      
     

反射慎用，奇慢无比。

相关参考：https://blog.csdn.net/livexy/article/details/6196193

http://www.cnblogs.com/liucfy/archive/2010/03/26/1696196.html

https://blog.csdn.net/lijing_zhaisky/article/details/7434622

https://www.cnblogs.com/livexy/archive/2010/09/01/1815330.html

---------------------

作者：bashigufen

来源：CSDN

原文：https://blog.csdn.net/lilong_herry/article/details/79993907