利用Emit动态生成代理对象监控对象哪些字段被修改,被修改为什么值
被Register的对象要监控的值必须是Virtual虚类型
必须使用CreateInstance创建对象
必须使用DynamicProxyGenerator.GetChangeProperties 获取改变的值
调用GetChangeProperties 返回的Dictionary.Clear() 重置当前已修改属性
对象赋值时增加变动修改,如果value 和原始值相同则不记录变动
支持注册多个对象到一个代理程序集
核心部分摘自 https://blog.csdn.net/lishuangquan1987/article/details/84312514
测试代码
using System;
using System.Diagnostics;
namespace TestApp
{
class Program
{
static void Main(string[] args)
{
DynamicProxyGenerator dpg = new DynamicProxyGenerator("DynamicAssembly");
//注册类型
dpg.Register<Person>();
dpg.Register<Person2>();
//保存为dll
dpg.Save();
Person p = dpg.CreateInstance<Person>();
p.Name = "tom";
p.Age = 12345;
var changes = DynamicProxyGenerator.GetChangeProperties(p);
Console.WriteLine($"第一次检测改变了{changes.Count}个属性");
changes.Clear();
p.Name = "tony";
p.Age = 12345;
changes = DynamicProxyGenerator.GetChangeProperties(p);
Console.WriteLine($"第二次检测改变了{changes.Count}个属性");
//创建对象测试
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
for (int i = 0; i < 100000; i++)
{
var p2 = dpg.CreateInstance<Person2>();
}
stopwatch.Stop();
Console.WriteLine($"创建对象100000个用时{stopwatch.ElapsedMilliseconds}ms");
Console.ReadKey();
}
}
public class Person
{
public virtual String Name { get; set; }
public virtual Int32 Age { get; set; }
}
public class Person2
{
public virtual String Name { get; set; }
public virtual Int32 Age { get; set; }
}
}
```
核心代码
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Reflection.Emit;
namespace TestApp
{
/// <summary>
/// 动态代理类生成器
/// </summary>
public class DynamicProxyGenerator
{
private const string ModifiedPropertyNamesFieldName = "ChangePropertys";
private const MethodAttributes GetSetMethodAttributes = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.CheckAccessOnOverride | MethodAttributes.Virtual | MethodAttributes.HideBySig;
/// <summary>
/// 程序集名称
/// </summary>
private AssemblyName assemblyName { get; set; }
/// <summary>
/// 程序集构建器
/// </summary>
private AssemblyBuilder assemblyBuilder { get; set; }
/// <summary>
/// 程序集模块
/// </summary>
private ModuleBuilder moduleBuilder { get; set; }
/// <summary>
/// 保存修改属性的集合类型
/// </summary>
private Type modifiedPropertyNamesType { get; set; }
/// <summary>
/// 构造一个动态代理生成器
/// </summary>
/// <param name="AssemblyName"></param>
/// <param name="isSaveDynamicModule"></param>
public DynamicProxyGenerator(String DynamicAssemblyName)
{
//创建程序集
assemblyName = new AssemblyName(DynamicAssemblyName);
assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.RunAndSave);
//动态创建模块
moduleBuilder = assemblyBuilder.DefineDynamicModule(String.Format("{0}Module", DynamicAssemblyName), String.Format("{0}.dll", DynamicAssemblyName));
//修改的属性集合类型
modifiedPropertyNamesType = typeof(Dictionary<String, Object>);
}
/// <summary>
/// 注册类型到代理生成器(只注册Virtual属性)
/// </summary>
/// <typeparam name="T">类</typeparam>
/// <returns></returns>
public void Register<T>()
{
Type typeNeedProxy = typeof(T);
//创建动态类代理,这里名字不变 继承自T
TypeBuilder typeBuilderProxy = moduleBuilder.DefineType(typeNeedProxy.Name, TypeAttributes.Public, typeNeedProxy);
//定义一个Dictionary变量存放属性变更名
FieldBuilder fbModifiedPropertyNames = typeBuilderProxy.DefineField(ModifiedPropertyNamesFieldName, modifiedPropertyNamesType, FieldAttributes.Public);
/*
* 构造函数 实例化 ModifiedPropertyNames,生成类似于下面的代码
ModifiedPropertyNames = new List<string>();
*/
ConstructorBuilder constructorBuilder = typeBuilderProxy.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, null);
ILGenerator ilgCtor = constructorBuilder.GetILGenerator();
ilgCtor.Emit(OpCodes.Ldarg_0);//加载当前类
ilgCtor.Emit(OpCodes.Newobj, modifiedPropertyNamesType.GetConstructor(new Type[0]));//实例化对象入栈
ilgCtor.Emit(OpCodes.Stfld, fbModifiedPropertyNames);//设置fbModifiedPropertyNames值,为刚入栈的实例化对象
ilgCtor.Emit(OpCodes.Ret);//返回
//获取被代理对象的所有属性,循环属性进行重写
PropertyInfo[] properties = typeNeedProxy.GetProperties();
foreach (PropertyInfo propertyInfo in properties)
{
string propertyName = propertyInfo.Name;
Type typePepropertyInfo = propertyInfo.PropertyType;
//动态创建字段和属性
FieldBuilder fieldBuilder = typeBuilderProxy.DefineField("_" + propertyName.ToLower(), typePepropertyInfo, FieldAttributes.Private);
PropertyBuilder propertyBuilder = typeBuilderProxy.DefineProperty(propertyName, PropertyAttributes.SpecialName, typePepropertyInfo, null);
//重写属性的Get Set方法
var methodGet = typeBuilderProxy.DefineMethod("get_" + propertyName, GetSetMethodAttributes, typePepropertyInfo, Type.EmptyTypes);
var methodSet = typeBuilderProxy.DefineMethod("set_" + propertyName, GetSetMethodAttributes, null, new Type[] { typePepropertyInfo });
//il of get method
var ilGetMethod = methodGet.GetILGenerator();
ilGetMethod.Emit(OpCodes.Ldarg_0);
ilGetMethod.Emit(OpCodes.Ldfld, fieldBuilder);
ilGetMethod.Emit(OpCodes.Ret);
//il of set method
ILGenerator ilSetMethod = methodSet.GetILGenerator();
//声明布尔类型
ilSetMethod.DeclareLocal(typeof(Boolean));
//声明一个标签,标记到ret
Label label = ilSetMethod.DefineLabel();
//判断值是否改变
ilSetMethod.Emit(OpCodes.Nop);
ilSetMethod.Emit(OpCodes.Ldarg_0);
ilSetMethod.Emit(OpCodes.Ldfld, fieldBuilder);
ilSetMethod.Emit(OpCodes.Ldarg_1);
ilSetMethod.Emit(OpCodes.Ceq);
ilSetMethod.Emit(OpCodes.Ldc_I4_0);
ilSetMethod.Emit(OpCodes.Ceq);
ilSetMethod.Emit(OpCodes.Stloc_0);
ilSetMethod.Emit(OpCodes.Ldloc_0);
//如果未改变,调到结束return
ilSetMethod.Emit(OpCodes.Brfalse_S, label);
//赋值
ilSetMethod.Emit(OpCodes.Nop);
ilSetMethod.Emit(OpCodes.Ldarg_0);
ilSetMethod.Emit(OpCodes.Ldarg_1);
ilSetMethod.Emit(OpCodes.Stfld, fieldBuilder);
//保存到 Dictionary
ilSetMethod.Emit(OpCodes.Ldarg_0);
ilSetMethod.Emit(OpCodes.Ldfld, fbModifiedPropertyNames);
ilSetMethod.Emit(OpCodes.Ldstr, propertyInfo.Name);
ilSetMethod.Emit(OpCodes.Ldarg_1);
ilSetMethod.Emit(OpCodes.Box, propertyInfo.PropertyType);
ilSetMethod.Emit(OpCodes.Callvirt, modifiedPropertyNamesType.GetMethod("set_Item", new Type[] { typeof(string), typeof(Object) }));
ilSetMethod.Emit(OpCodes.Nop);
ilSetMethod.Emit(OpCodes.Nop);
ilSetMethod.MarkLabel(label);
ilSetMethod.Emit(OpCodes.Ret);
//设置属性的Get Set方法
propertyBuilder.SetGetMethod(methodGet);
propertyBuilder.SetSetMethod(methodSet);
}
//引用下, 要不无法生成
Type proxyClassType = typeBuilderProxy.CreateType();
}
/// <summary>
/// 保存程序集到dll文件
/// </summary>
public void Save()
{
assemblyBuilder.Save($"{assemblyName.Name}.dll");
}
/// <summary>
/// 创建实例
/// </summary>
/// <typeparam name="T"></typeparam>
/// <returns></returns>
public T CreateInstance<T>()
{
Type typeNeedProxy = typeof(T);
return (T)assemblyBuilder.CreateInstance(typeNeedProxy.Name);
}
/// <summary>
/// 获取属性的变更名称,
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
public static Dictionary<String, Object> GetChangeProperties<T>(T obj)
{
FieldInfo fieldInfo = obj.GetType().GetField(ModifiedPropertyNamesFieldName);
if (fieldInfo == null) return null;
object value = fieldInfo.GetValue(obj);
return value as Dictionary<String, Object>;
}
}
}
```
来源：https://blog.csdn.net/Vblegend_2013/article/details/85228041