动态创建类

  1     public class CreateClassHelper
  2     {
  3         /// <summary>
  4         /// 根据列名创建自定义类型
  5         /// 属性名称在列名前添加前缀 prdfix
  6         /// </summary>
  7         /// <param name="columnNames">用来创建属性的列名</param>
  8         /// <param name="prdfix">属性名称在列名前添加的前缀</param>
  9         /// <returns></returns>
 10         public static Type CreateClass(string[] columnNames, string prdfix=null)
 11         {
 12             
 13             DynamicTypeBuilder dyClass = new DynamicTypeBuilder("dy");//创建动态类，dy可以随便替换  
 14             //ColInfos为已经取到的列信息集合  
 15             foreach (string name in columnNames)
 16             {
 17                 try
 18                 {
 19                     dyClass.AppendPublicProperty(prdfix + name, typeof(string));//同时动态添加公共属性到自定义类  
 20                 }
 21                 catch (Exception ex)
 22                 {
 23                     LogHelper.log4net_Error(ex.Message.ToString(), null);
 24                 }        
 25             }
 26             Type dyType = dyClass.CreateDynamicType();//创建自定义类   
 27             return dyType;
 28         }
 29     }
 30     public class DynamicTypeBuilder
 31     {
 32         TypeBuilder tb;
 33         /// <summary>  
 34         /// 构造函数  
 35         /// </summary>  
 36         /// <param name="typeNm">动态类型的名称</param>  
 37         public DynamicTypeBuilder(string typeNm)
 38         {
 39             // 在 Silverlight 中 AssemblyBuilderAccess 没有 RunAndSave  
 40             AssemblyBuilder ab = AppDomain.CurrentDomain.DefineDynamicAssembly(
 41                 new AssemblyName("TempAssembly"), AssemblyBuilderAccess.Run);
 42 
 43             ModuleBuilder mb = ab.DefineDynamicModule("TempModule");
 44             this.tb = mb.DefineType(typeNm, TypeAttributes.Public);
 45         }
 46         /// <summary>  
 47         /// 添加一个public的可读写属性，并且会创建对应的名为 propertyNm + "Field" 的私有字段  
 48         /// </summary>  
 49         /// <param name="propertyNm"></param>  
 50         /// <param name="type"></param>  
 51         public void AppendPublicProperty(string propertyNm, Type type)
 52         {
 53             this.AppendPublicProperty(propertyNm, type, true, true);
 54         }
 55         /// <summary>  
 56         /// 添加一个public属性，并且会创建对应的名为 propertyNm + "Field" 的私有字段  
 57         /// </summary>  
 58         /// <param name="propertyNm"></param>  
 59         /// <param name="type"></param>  
 60         /// <param name="canGet">是否实现getter</param>  
 61         /// <param name="canSet">是否实现setter</param>  
 62         public void AppendPublicProperty(string propertyNm, Type type, bool canGet, bool canSet)
 63         {
 64             FieldBuilder field = this.tb.DefineField(string.Format("{0}Field", propertyNm), type, FieldAttributes.Private);
 65 
 66             PropertyBuilder property = tb.DefineProperty(propertyNm, PropertyAttributes.HasDefault, type, null);
 67 
 68             MethodAttributes getSetAttr = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig;
 69 
 70             if (canGet)
 71             {
 72                 MethodBuilder getAccessor = tb.DefineMethod(string.Format("get_{0}", propertyNm), getSetAttr, type, Type.EmptyTypes);
 73                 ILGenerator getIL = getAccessor.GetILGenerator();
 74                 // For an instance property, argument default is the instance. Load the  
 75                 // instance, then load the private field and return, leaving the  
 76                 // field value on the stack.  
 77                 getIL.Emit(OpCodes.Ldarg_0);
 78                 getIL.Emit(OpCodes.Ldfld, field);
 79                 getIL.Emit(OpCodes.Ret);
 80                 property.SetGetMethod(getAccessor);
 81             }
 82 
 83             if (canSet)
 84             {
 85                 MethodBuilder setAccessor = tb.DefineMethod(string.Format("set_{0}", propertyNm), getSetAttr, null, new Type[] { type });
 86                 setAccessor.DefineParameter(1, ParameterAttributes.None, "value");
 87                 ILGenerator setIL = setAccessor.GetILGenerator();
 88                 // Load the instance and then the numeric argument, then store the  
 89                 // argument in the field.  
 90                 setIL.Emit(OpCodes.Ldarg_0);
 91                 setIL.Emit(OpCodes.Ldarg_1);
 92                 setIL.Emit(OpCodes.Stfld, field);
 93                 setIL.Emit(OpCodes.Ret);
 94                 property.SetSetMethod(setAccessor);
 95             }
 96         }
 97         /// <summary>  
 98         /// 在添加完各个 public 属性之后，调用此方法以完成对动态类型的定义并加载之，  
 99         /// 此后通过 Activator.CreateInstance() 便可实例化动态类型  
100         /// </summary>  
101         /// <returns></returns>  
102         public Type CreateDynamicType()
103         {
104             return this.tb.CreateType();
105         }
106     }