使用 Reflection.Emit 动态创建类.我卡住了

本文关键字：创建 Reflection Emit 动态 使用 | 更新日期: 2023-09-27 17:55:17

阅读有关在运行时创建类型的书籍，我发现它很棒。我的目标是创建这个类：

[DelimitedRecord(",")]
public class Person
{
    [FieldOrder(0)]
    private string firstName;
    [FieldOrder(1)]
    private string lastName;
    public string FirstName
    {
        get { return firstName; }
        set { firstName = value; }
    }
    public string LastName
    {
        get { return lastName; }
        set { lastName = value; }
    }
}

我这样做了：

//create the builder
AssemblyName assembly = new AssemblyName("FileHelpersTests");
AppDomain appDomain = System.Threading.Thread.GetDomain();
AssemblyBuilder assemblyBuilder = appDomain.DefineDynamicAssembly(assembly, AssemblyBuilderAccess.Run);
ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(assembly.Name);
//create the class
TypeBuilder typeBuilder = moduleBuilder.DefineType("Person", TypeAttributes.Public | TypeAttributes.AutoClass | TypeAttributes.AnsiClass |
                                                    TypeAttributes.BeforeFieldInit, typeof(System.Object));
//create the Delimiter attribute
//create the firstName field
FieldBuilder firstNameField = typeBuilder.DefineField("firstName", typeof(System.String), FieldAttributes.Private);
//create the firstName attribute [FieldOrder(0)]
//create the FirstName property
PropertyBuilder firstNameProperty = typeBuilder.DefineProperty("FirstName", PropertyAttributes.HasDefault, typeof(System.String), null);
//create the FirstName Getter
MethodBuilder firstNamePropertyGetter = typeBuilder.DefineMethod("get_FirstName", MethodAttributes.Public | MethodAttributes.SpecialName |
                                                                  MethodAttributes.HideBySig, typeof(System.String), Type.EmptyTypes);
ILGenerator firstNamePropertyGetterIL = firstNamePropertyGetter.GetILGenerator();
firstNamePropertyGetterIL.Emit(OpCodes.Ldarg_0);
firstNamePropertyGetterIL.Emit(OpCodes.Ldfld, firstNameField);
firstNamePropertyGetterIL.Emit(OpCodes.Ret);
//create the FirstName Setter
MethodBuilder firstNamePropertySetter = typeBuilder.DefineMethod("set_FirstName", MethodAttributes.Public | MethodAttributes.SpecialName |
                                                    MethodAttributes.HideBySig, null, new Type[] { typeof(System.String) });
ILGenerator firstNamePropertySetterIL = firstNamePropertySetter.GetILGenerator();
firstNamePropertySetterIL.Emit(OpCodes.Ldarg_0);
firstNamePropertySetterIL.Emit(OpCodes.Ldarg_1);
firstNamePropertySetterIL.Emit(OpCodes.Stfld, firstNameField);
firstNamePropertySetterIL.Emit(OpCodes.Ret);
//assign getter and setter
firstNameProperty.SetGetMethod(firstNamePropertyGetter);
firstNameProperty.SetSetMethod(firstNamePropertySetter);

//create the lastName field
FieldBuilder lastNameField = typeBuilder.DefineField("lastName", typeof(System.String), FieldAttributes.Private);
//create the lastName attribute [FieldOrder(1)]
//create the LastName property
PropertyBuilder lastNameProperty = typeBuilder.DefineProperty("LastName", PropertyAttributes.HasDefault, typeof(System.String), null);
//create the LastName Getter
MethodBuilder lastNamePropertyGetter = typeBuilder.DefineMethod("get_LastName", MethodAttributes.Public | MethodAttributes.SpecialName |
                                                                  MethodAttributes.HideBySig, typeof(System.String), Type.EmptyTypes);
ILGenerator lastNamePropertyGetterIL = lastNamePropertyGetter.GetILGenerator();
lastNamePropertyGetterIL.Emit(OpCodes.Ldarg_0);
lastNamePropertyGetterIL.Emit(OpCodes.Ldfld, lastNameField);
lastNamePropertyGetterIL.Emit(OpCodes.Ret);
//create the FirstName Setter
MethodBuilder lastNamePropertySetter = typeBuilder.DefineMethod("set_FirstName", MethodAttributes.Public | MethodAttributes.SpecialName |
                                                    MethodAttributes.HideBySig, null, new Type[] { typeof(System.String) });
ILGenerator lastNamePropertySetterIL = lastNamePropertySetter.GetILGenerator();
lastNamePropertySetterIL.Emit(OpCodes.Ldarg_0);
lastNamePropertySetterIL.Emit(OpCodes.Ldarg_1);
lastNamePropertySetterIL.Emit(OpCodes.Stfld, lastNameField);
lastNamePropertySetterIL.Emit(OpCodes.Ret);
//assign getter and setter
lastNameProperty.SetGetMethod(lastNamePropertyGetter);
lastNameProperty.SetSetMethod(lastNamePropertySetter);

我在创建这些属性时遇到了困难：

  • 班级级别的一个
  • 现场一级的那个

这是我点击时 ILDASM 显示的内容

  1. 构造函数

    .class public auto ansi beforefieldinit FileHelpersTests.Person
    extends [mscorlib]System.Object
{
    .custom instance void [FileHelpers]FileHelpers.DelimitedRecordAttribute::.ctor(string) = ( 01 00 01 2C 00 00 )           // ...,..
} // end of class FileHelpersTests.Person

  2. "名字"字段

    .field private string firstName
.custom instance void [FileHelpers]FileHelpers.FieldOrderAttribute::.ctor(int32) = ( 01 00 00 00 00 00 00 00 )

使用 Reflection.Emit 动态创建类.我卡住了

我让它工作了：

//create the Delimiter attribute
Type[] attributeParams = new Type[] { typeof(string) };
ConstructorInfo classCtorInfo = typeof(DelimitedRecordAttribute).GetConstructor(attributeParams);
CustomAttributeBuilder attributeBuilder = new CustomAttributeBuilder(classCtorInfo, new object[] { ";" });
typeBuilder.SetCustomAttribute(attributeBuilder);

这将完成字段属性的工作：

//create the firstName attribute [FieldOrder(0)]
Type[] firstNameFieldOrderAttributeParams = new Type[] { typeof(int) };
ConstructorInfo firstNameFieldOrderAttrInfo = typeof(FieldOrderAttribute).GetConstructor(firstNameFieldOrderAttributeParams);
CustomAttributeBuilder firstNameFieldOrderAttributeBuilder = new CustomAttributeBuilder(firstNameFieldOrderAttrInfo, new object[] { 0 });
firstNameField.SetCustomAttribute(firstNameFieldOrderAttributeBuilder);
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