动态方法DynamicMethod简例
using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Globalization;
public class Test
{
private delegate int HelloDelegate(string msg, int ret);
public static void Main()
{
//------------ 创建动态方法 START ----------------------------------
Type[] helloArgs = { typeof(string), typeof(int) };//方法参数类型
DynamicMethod hello = new DynamicMethod("Hello",typeof(int),helloArgs,typeof(string).Module);
Type[] writeStringArgs = { typeof(string) };
MethodInfo writeString = typeof(Console).GetMethod("WriteLine",writeStringArgs);
ILGenerator il = hello.GetILGenerator(256);//生成中间语言(MSIL)指令
il.Emit(OpCodes.Ldarg_0);//将指定指令放入指令流
il.EmitCall(OpCodes.Call, writeString, null);//将Call或callvirt指令放到指令流，以便调用varargs方法
il.Emit(OpCodes.Ldarg_1);//将指定指令放入指令流
il.Emit(OpCodes.Ret);//将指定指令放入指令流
hello.DefineParameter(1, ParameterAttributes.In, "message");//定义动态方法的参数
hello.DefineParameter(2, ParameterAttributes.In, "valueToReturn");//定义动态方法的参数
HelloDelegate hi = (HelloDelegate)hello.CreateDelegate(typeof(HelloDelegate));//完成动态方法并创建一个可用于执行该方法的委托
//此时 hi 即为可以调用的方法名，真正的方法名是 Hello , hi只是用委托的方式调用,以下还可以用Invoke方式调用
//------------- 创建动态方法 END -----------------------
//------------ 以下为调用部分 ----------------------------
Console.WriteLine("\r\nUse the delegate to execute the dynamic method:");
Console.ReadLine();
int retval = hi("\r\nHello, World!", 42);
Console.ReadLine();
Console.WriteLine("Invoking delegate hi(\"Hello, World!\", 42) returned: " + retval);
Console.ReadLine();
retval = hi("\r\nHi, Mom!", 5280);
Console.ReadLine();
Console.WriteLine("Invoking delegate hi(\"Hi, Mom!\", 5280) returned: " + retval);
Console.ReadLine();
Console.WriteLine("\r\nUse the Invoke method to execute the dynamic method:");
Console.ReadLine();
object[] invokeArgs = { "\r\nHello, World!", 42 };
Console.ReadLine();
object objRet = hello.Invoke(null, BindingFlags.ExactBinding, null, invokeArgs, new CultureInfo("en-us"));//调用动态方法
Console.WriteLine("hello.Invoke returned: " + objRet);
Console.ReadLine();
Console.WriteLine("\r\n ----- Display information about the dynamic method -----");
Console.ReadLine();
Console.WriteLine("\r\nMethod Attributes: {0}", hello.Attributes);//创建动态方法指定的属性
Console.ReadLine();
Console.WriteLine("\r\nCalling convention: {0}", hello.CallingConvention);//创建动态方法时指定的调用约定
Console.ReadLine();
if (hello.DeclaringType == null)//获取动态方法，对于动态方法类型始终为null
{
Console.WriteLine("\r\nDeclaringType is always null for dynamic methods.");
Console.ReadLine();
}
else
{
Console.WriteLine("DeclaringType: {0}", hello.DeclaringType);
Console.ReadLine();
}
if (hello.InitLocals)//获取或设置一个值，该值指示方法中的局部变量是否初始化为零
{
Console.Write("\r\nThis method contains verifiable code.");
Console.ReadLine();
}
else
{
Console.Write("\r\nThis method contains unverifiable code.");
Console.ReadLine();
}
Console.WriteLine(" (InitLocals = {0})", hello.InitLocals);
Console.ReadLine();
Console.WriteLine("\r\nModule: {0}", hello.Module);//获取动态方法逻辑关联的模块
Console.ReadLine();
Console.WriteLine("\r\nName: {0}", hello.Name);//获取动态方法的名称
Console.ReadLine();
if (hello.ReflectedType == null)//获取在反射中用于获取方法的类
{
Console.WriteLine("\r\nReflectedType is null.");
Console.ReadLine();
}
else
{
Console.WriteLine("\r\nReflectedType: {0}", hello.ReflectedType);
Console.ReadLine();
}
if (hello.ReturnParameter == null)//获取动态方法的返回参数
{
Console.WriteLine("\r\nMethod has no return parameter.");
Console.ReadLine();
}
else
{
Console.WriteLine("\r\nReturn parameter: {0}", hello.ReturnParameter);
Console.ReadLine();
}
Console.WriteLine("\r\nReturn type: {0}", hello.ReturnType);//获取动态方法的返回值类型
Console.ReadLine();
if (hello.ReturnType == typeof(void))
{
Console.WriteLine("The method has no return type.");
Console.ReadLine();
}
else
{
ICustomAttributeProvider caProvider = hello.ReturnTypeCustomAttributes;//获取动态方法的返回类型的自定义属性
object[] returnAttributes = caProvider.GetCustomAttributes(true);
if (returnAttributes.Length == 0)
{
Console.WriteLine("\r\nThe return type has no custom attributes.");
Console.ReadLine();
}
else
{
Console.WriteLine("\r\nThe return type has the following custom attributes:");
Console.ReadLine();
foreach (object attr in returnAttributes)
{
Console.WriteLine("\t{0}", attr.ToString());
}
Console.ReadLine();
}
}
Console.WriteLine("\r\nToString: {0}", hello.ToString());//返回方法的签名，以字符串表示
Console.ReadLine();
ParameterInfo[] parameters = hello.GetParameters();//获取动态方法的参数
Console.WriteLine("\r\nParameters: name, type, ParameterAttributes");
Console.ReadLine();
foreach (ParameterInfo p in parameters)
{
Console.WriteLine("\t{0}, {1}, {2}",
p.Name, p.ParameterType, p.Attributes);
}
Console.ReadLine();
}
}
