如何定义带有一个模块的动态程序集

下面的代码示例演示如何定义带有一个模块的动态程序集。 该示例程序集中的模块包含一个类型 MyDynamicType，该类型具有私有字段、获取和设置私有字段的属性、初始化私有字段的构造函数，以及将用户提供的数与私有字段值相乘并返回结果的方法。

创建程序集时指定 AssemblyBuilderAccess.RunAndSave。 程序集代码可立即使用，并且程序集将保存到磁盘，以便可以使用 Ildasm.exe（MSIL 反汇编程序） 对其进行检查或将其用于另一个程序。

 

using System; using System.Reflection; using System.Reflection.Emit; class DemoAssemblyBuilder { public static void Main() { // An assembly consists of one or more modules, each of which // contains zero or more types. This code creates a single-module // assembly, the most common case. The module contains one type, // named "MyDynamicType", that has a private field, a property // that gets and sets the private field, constructors that // initialize the private field, and a method that multiplies // a user-supplied number by the private field value and returns // the result. In C# the type might look like this: /* public class MyDynamicType { private int m_number; public MyDynamicType() : this(42) {} public MyDynamicType(int initNumber) { m_number = initNumber; } public int Number { get { return m_number; } set { m_number = value; } } public int MyMethod(int multiplier) { return m_number * multiplier; } } */ AssemblyName aName = new AssemblyName("DynamicAssemblyExample"); AssemblyBuilder ab = AppDomain.CurrentDomain.DefineDynamicAssembly( aName, AssemblyBuilderAccess.RunAndSave); // For a single-module assembly, the module name is usually // the assembly name plus an extension. ModuleBuilder mb = ab.DefineDynamicModule(aName.Name, aName.Name + ".dll"); TypeBuilder tb = mb.DefineType( "MyDynamicType", TypeAttributes.Public); // Add a private field of type int (Int32). FieldBuilder fbNumber = tb.DefineField( "m_number", typeof(int), FieldAttributes.Private); // Define a constructor that takes an integer argument and // stores it in the private field. Type[] parameterTypes = { typeof(int) }; ConstructorBuilder ctor1 = tb.DefineConstructor( MethodAttributes.Public, CallingConventions.Standard, parameterTypes); ILGenerator ctor1IL = ctor1.GetILGenerator(); // For a constructor, argument zero is a reference to the new // instance. Push it on the stack before calling the base // class constructor. Specify the default constructor of the // base class (System.Object) by passing an empty array of // types (Type.EmptyTypes) to GetConstructor. ctor1IL.Emit(OpCodes.Ldarg_0); ctor1IL.Emit(OpCodes.Call, typeof(object).GetConstructor(Type.EmptyTypes)); // Push the instance on the stack before pushing the argument // that is to be assigned to the private field m_number. ctor1IL.Emit(OpCodes.Ldarg_0); ctor1IL.Emit(OpCodes.Ldarg_1); ctor1IL.Emit(OpCodes.Stfld, fbNumber); ctor1IL.Emit(OpCodes.Ret); // Define a default constructor that supplies a default value // for the private field. For parameter types, pass the empty // array of types or pass null. ConstructorBuilder ctor0 = tb.DefineConstructor( MethodAttributes.Public, CallingConventions.Standard, Type.EmptyTypes); ILGenerator ctor0IL = ctor0.GetILGenerator(); // For a constructor, argument zero is a reference to the new // instance. Push it on the stack before pushing the default // value on the stack, then call constructor ctor1. ctor0IL.Emit(OpCodes.Ldarg_0); ctor0IL.Emit(OpCodes.Ldc_I4_S, 42); ctor0IL.Emit(OpCodes.Call, ctor1); ctor0IL.Emit(OpCodes.Ret); // Define a property named Number that gets and sets the private // field. // // The last argument of DefineProperty is null, because the // property has no parameters. (If you don't specify null, you must // specify an array of Type objects. For a parameterless property, // use the built-in array with no elements: Type.EmptyTypes) PropertyBuilder pbNumber = tb.DefineProperty( "Number", PropertyAttributes.HasDefault, typeof(int), null); // The property "set" and property "get" methods require a special // set of attributes. MethodAttributes getSetAttr = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig; // Define the "get" accessor method for Number. The method returns // an integer and has no arguments. (Note that null could be // used instead of Types.EmptyTypes) MethodBuilder mbNumberGetAccessor = tb.DefineMethod( "get_Number", getSetAttr, typeof(int), Type.EmptyTypes); ILGenerator numberGetIL = mbNumberGetAccessor.GetILGenerator(); // For an instance property, argument zero is the instance. Load the // instance, then load the private field and return, leaving the // field value on the stack. numberGetIL.Emit(OpCodes.Ldarg_0); numberGetIL.Emit(OpCodes.Ldfld, fbNumber); numberGetIL.Emit(OpCodes.Ret); // Define the "set" accessor method for Number, which has no return // type and takes one argument of type int (Int32). MethodBuilder mbNumberSetAccessor = tb.DefineMethod( "set_Number", getSetAttr, null, new Type[] { typeof(int) }); ILGenerator numberSetIL = mbNumberSetAccessor.GetILGenerator(); // Load the instance and then the numeric argument, then store the // argument in the field. numberSetIL.Emit(OpCodes.Ldarg_0); numberSetIL.Emit(OpCodes.Ldarg_1); numberSetIL.Emit(OpCodes.Stfld, fbNumber); numberSetIL.Emit(OpCodes.Ret); // Last, map the "get" and "set" accessor methods to the // PropertyBuilder. The property is now complete. pbNumber.SetGetMethod(mbNumberGetAccessor); pbNumber.SetSetMethod(mbNumberSetAccessor); // Define a method that accepts an integer argument and returns // the product of that integer and the private field m_number. This // time, the array of parameter types is created on the fly. MethodBuilder meth = tb.DefineMethod( "MyMethod", MethodAttributes.Public, typeof(int), new Type[] { typeof(int) }); ILGenerator methIL = meth.GetILGenerator(); // To retrieve the private instance field, load the instance it // belongs to (argument zero). After loading the field, load the // argument one and then multiply. Return from the method with // the return value (the product of the two numbers) on the // execution stack. methIL.Emit(OpCodes.Ldarg_0); methIL.Emit(OpCodes.Ldfld, fbNumber); methIL.Emit(OpCodes.Ldarg_1); methIL.Emit(OpCodes.Mul); methIL.Emit(OpCodes.Ret); // Finish the type. Type t = tb.CreateType(); // The following line saves the single-module assembly. This // requires AssemblyBuilderAccess to include Save. You can now // type "ildasm MyDynamicAsm.dll" at the command prompt, and // examine the assembly. You can also write a program that has // a reference to the assembly, and use the MyDynamicType type. // ab.Save(aName.Name + ".dll"); // Because AssemblyBuilderAccess includes Run, the code can be // executed immediately. Start by getting reflection objects for // the method and the property. MethodInfo mi = t.GetMethod("MyMethod"); PropertyInfo pi = t.GetProperty("Number"); // Create an instance of MyDynamicType using the default // constructor. object o1 = Activator.CreateInstance(t); // Display the value of the property, then change it to 127 and // display it again. Use null to indicate that the property // has no index. Console.WriteLine("o1.Number: {0}", pi.GetValue(o1, null)); pi.SetValue(o1, 127, null); Console.WriteLine("o1.Number: {0}", pi.GetValue(o1, null)); // Call MyMethod, passing 22, and display the return value, 22 // times 127. Arguments must be passed as an array, even when // there is only one. object[] arguments = { 22 }; Console.WriteLine("o1.MyMethod(22): {0}", mi.Invoke(o1, arguments)); // Create an instance of MyDynamicType using the constructor // that specifies m_Number. The constructor is identified by // matching the types in the argument array. In this case, // the argument array is created on the fly. Display the // property value. object o2 = Activator.CreateInstance(t, new object[] { 5280 }); Console.WriteLine("o2.Number: {0}", pi.GetValue(o2, null)); } } /* This code produces the following output: o1.Number: 42 o1.Number: 127 o1.MyMethod(22): 2794 o2.Number: 5280 */

 

生成的DynamicAssemblyExample.dll，经过反编译后，代码如下：

using System; public class MyDynamicType { private int m_number; public MyDynamicType() : this(0x2a) { } public MyDynamicType(int num1) { this.m_number = num1; } public int MyMethod(int num1) { return (this.m_number * num1); } public int Number { get { return this.m_number; } set { this.m_number = value; } } }

 

参考：http://msdn.microsoft.com/zh-cn/library/system.reflection.emit.assemblybuilder.aspx