var dllpath = "xxx.dll";
            Assembly assembly = Assembly.LoadFrom(dllpath);//構建Assembly+Module
            Type dataAccessType = assembly.GetType("xxxxx");//構建Class(MethodTable+EEClass)
            object dataAccess = Activator.CreateInstance(dataAccessType);//在托管堆中創(chuàng)建MT實例
            MethodInfo addMethod = dataAccessType.GetMethod("Add");//構建MethodDesc
            addMethod.Invoke(dataAccess, new object[] { "hello world" });//調(diào)用方法

Type t = typeof(System.IO.FileStream);
FieldInfo[] fi = t.GetFields(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public);
PropertyInfo[] pi = t.GetProperties(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public);
EventInfo[] ei = t.GetEvents(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public);
......

            AssemblyBuilder ab = AssemblyBuilder.DefineDynamicAssembly(new AssemblyName("MyAssembly"), AssemblyBuilderAccess.RunAndCollect);//創(chuàng)建Assembly
            ModuleBuilder mob = ab.DefineDynamicModule("MyModule");//創(chuàng)建Module
            TypeBuilder tb = mob.DefineType("MyType", TypeAttributes.Public | TypeAttributes.Class);//創(chuàng)建Class
            MethodBuilder mb = tb.DefineMethod("SumMethod", MethodAttributes.Public | MethodAttributes.Static, typeof(int), new Type[] { typeof(int), typeof(int) });//創(chuàng)建MethodTable
            ILGenerator il = mb.GetILGenerator();//通過IL API 動態(tài)構建MethodDesc
            il.Emit(OpCodes.Ldarg_0);
            il.Emit(OpCodes.Ldarg_1);
            il.Emit(OpCodes.Add);
            il.Emit(OpCodes.Ret);
            Type type = tb.CreateType();  //mt + eeclass
            MethodInfo method = type.GetMethod("SumMethod");
            Console.WriteLine(method.Invoke(null, new object[] { 5, 10 }));

public class Person
{
    private int _age;
    public override string ToString()
    {
        return _age.ToString();
    }
}
static void EmitTest(Person person)
{
    // 獲取Person類的類型對象
    Type personType = typeof(Person);
    // 獲取私有字段_age的FieldInfo，無法避免部分使用反射
    FieldInfo ageField = personType.GetField("_age", BindingFlags.Instance | BindingFlags.NonPublic);
    if (ageField == null)
    {
        throw new ArgumentException("未找到指定的私有字段");
    }
    // 創(chuàng)建一個動態(tài)方法
    DynamicMethod dynamicMethod = new DynamicMethod("SetAgeValue", null, new Type[] { typeof(Person), typeof(int) }, personType);
    // 獲取IL生成器
    ILGenerator ilGenerator = dynamicMethod.GetILGenerator();
    // 將傳入的Person對象加載到計算棧上（this指針）
    ilGenerator.Emit(OpCodes.Ldarg_0);
    // 將傳入的新值加載到計算棧上
    ilGenerator.Emit(OpCodes.Ldarg_1);
    // 將新值存儲到對應的私有字段中
    ilGenerator.Emit(OpCodes.Stfld, ageField);
    // 返回（因為方法無返回值，這里只是結束方法執(zhí)行）
    ilGenerator.Emit(OpCodes.Ret);
    // 創(chuàng)建委托類型，其簽名與動態(tài)方法匹配
    Action<Person, int> setAgeAction = (Action<Person, int>)dynamicMethod.CreateDelegate(typeof(Action<Person, int>));
    // 通過委托調(diào)用動態(tài)生成的方法來修改私有字段的值
    setAgeAction(person, 100);
}

static void ExpressionTest(Person person)
{
    // 獲取Person類的類型對象
    Type personType = typeof(Person);
    // 獲取私有字段_age的FieldInfo，無法避免部分使用反射
    FieldInfo ageField = personType.GetField("_age", BindingFlags.Instance | BindingFlags.NonPublic);
    if (ageField == null)
    {
        throw new ArgumentException("未找到指定的私有字段");
    }
    // 創(chuàng)建參數(shù)表達式，對應傳入的Person對象實例
    ParameterExpression instanceParam = Expression.Parameter(personType, "instance");
    // 創(chuàng)建參數(shù)表達式，對應傳入的新值
    ParameterExpression newValueParam = Expression.Parameter(typeof(int), "newValue");
    // 創(chuàng)建一個賦值表達式，將新值賦給私有字段
    BinaryExpression assignExpression = Expression.Assign(Expression.Field(instanceParam, ageField), newValueParam);
    // 創(chuàng)建一個包含賦值表達式的表達式塊，這里因為只有一個賦值操作，所以塊里就這一個表達式
    BlockExpression blockExpression = Expression.Block(assignExpression);
    // 創(chuàng)建一個可執(zhí)行的委托，其類型與表達式塊的邏輯匹配
    Action<Person, int> setAgeAction = Expression.Lambda<Action<Person, int>>(blockExpression, instanceParam, newValueParam).Compile();
    // 通過委托調(diào)用表達式樹生成的邏輯來修改私有字段的值
    setAgeAction(person, 100);
}

static void New()
{
    var person = new Person();
    GetAgeField(person) = 100;
}
[UnsafeAccessor(UnsafeAccessorKind.Field, Name = "_age")]
static extern ref int GetAgeField(Person counter);