C# 使用Emit实现动态AOP框架 (三)

准备工作完成后，DynamicProxy类就可以开始了。

创建代理对象 Create

    创建代理对象主要分为五步：

   (1)、获取被代理类型构造函数参数列表

   Type[] parameterTypes = parameters == null ? Type.EmptyTypes : parameters.Select(p => p.GetType()).ToArray();

 (2)、根据构造函数参数列表创建代理类型

    Type proxyType = CreateProxyType(srcType, parameterTypes);

 (3)、使用动态方法生成创建代理类型实例的委托

    CreateFunc<T>(proxyType, parameterTypes)

 (4)、生成ProxyType对象，存入代理类型字典，以备二次调用

     obj = new ProxyType<T>(srcType.FullName, signature, CreateFunc<T>(proxyType, parameterTypes));

     func_Dictionary.Add(srcType.FullName + "(" + signature + ")", obj);

(5)、通过委托生成代理对象

     Func<object[], T> func = (obj as ProxyType<T>).CreateFunc;

      if (func == null)
           throw new Exception("unknown exception");

      return func(parameters);

 1         /// <summary>
 2         /// 创建代理类型
 3         /// </summary>
 4         /// <param name="srcType">类型</param>
 5         /// <param name="parameterTypes">参数</param>
 6         /// <returns></returns>
 7         private static Type CreateProxyType(Type srcType, Type[] parameterTypes)
 8         {
 9             XNet.XCore.XDynamic.BuilderCollection bc = new XDynamic.BuilderCollection
10                                                        (srcType.Name + "_Aop_Assmely", srcType.Name + "_Aop_Module", srcType.Name + "_Proxy", srcType, parameterTypes);
11 
12 
13             foreach (var propertyInfo in srcType.GetProperties())
14                 OverrideProperty(bc.DynamicTypeBuilder, propertyInfo);
15 
16             //切入方法
17             MethodInfo[] methods = srcType.GetMethods(BindingFlags.Public | BindingFlags.Instance);
18 
19             for (int i = 0; i < methods.Length; i++)
20             {
21                 var method = methods[i];
22 
23                 if (!method.IsPublic || !method.IsVirtual || XDynamic.IsObjectMethod(method)) continue;
24 
25                 object[] aspectAttributes = method.GetCustomAttributes(typeof(AspectAttribute), false);
26 
27                 OverrideMethod(bc.DynamicTypeBuilder, method, aspectAttributes);
28             }
29 
30             Type result = bc.DynamicTypeBuilder.CreateType();
31 
32             bc.DynamicAssemblyBuilder.Save(bc.AssemblyName.Name + ".dll");
33 
34             return result;
35         }

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1.1、根据构造函数参数列表创建代理类型 CreateProxyType

 (1)、通过Emit生成动态程序集、动态模块以及动态类型 

     XNet.XCore.XDynamic.BuilderCollection bc = new XDynamic.BuilderCollection
        (srcType.Name + "_Aop_Assmely", srcType.Name + "_Aop_Module", srcType.Name + "_Proxy", srcType, parameterTypes);

（2）、重写被切入的属性

    OverrideProperty(bc.DynamicTypeBuilder, propertyInfo);

（3）、重写被切入的方法

     OverrideMethod(bc.DynamicTypeBuilder, method, aspectAttributes);

 （4）、生成代理类型

    Type result = bc.DynamicTypeBuilder.CreateType();

 1         /// <summary>
 2          /// 创建代理类型
 3         /// </summary>
 4         /// <param name="srcType">类型</param>
 5         /// <param name="parameterTypes">参数</param>
 6         /// <returns></returns>
 7         private static Type CreateProxyType(Type srcType, Type[] parameterTypes)
 8         {
 9             XNet.XCore.XDynamic.BuilderCollection bc = new XDynamic.BuilderCollection
10                                                        (srcType.Name + "_Aop_Assmely", srcType.Name + "_Aop_Module", srcType.Name + "_Proxy", srcType, parameterTypes);
11 
12 
13             foreach (var propertyInfo in srcType.GetProperties())
14                 OverrideProperty(bc.DynamicTypeBuilder, propertyInfo);
15 
16             //切入方法
17             MethodInfo[] methods = srcType.GetMethods(BindingFlags.Public | BindingFlags.Instance);
18 
19             for (int i = 0; i < methods.Length; i++)
20             {
21                 var method = methods[i];
22 
23                 if (!method.IsPublic || !method.IsVirtual || XDynamic.IsObjectMethod(method)) continue;
24 
25                 object[] aspectAttributes = method.GetCustomAttributes(typeof(AspectAttribute), false);
26 
27                 OverrideMethod(bc.DynamicTypeBuilder, method, aspectAttributes);
28             }
29 
30             Type result = bc.DynamicTypeBuilder.CreateType();
31 
32             bc.DynamicAssemblyBuilder.Save(bc.AssemblyName.Name + ".dll");
33 
34             return result;
35         }

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1.1.1 重写被切入的属性 OverrideProperty

 1        /// <summary>
 2         /// 重写被代理类的属性
 3         /// </summary>
 4         /// <param name="dynamicTypeBuilder"></param>
 5         /// <param name="info">属性信息</param>
 6         /// <param name="rangeType">切面范围</param>
 7         /// <param name="onEntryExit">切面公共调用方法</param>
 8         private static void OverrideProperty(TypeBuilder dynamicTypeBuilder, PropertyInfo info)
 9         {
10             //不需要切入直接返回
11             object[] aspectAttributes = info.GetCustomAttributes(typeof(AspectAttribute), false);
12 
13             if (aspectAttributes.Length == 0) return;
14 
15             PropertyBuilder dynamicPropertyBuilder = dynamicTypeBuilder.DefineProperty(info.Name, PropertyAttributes.HasDefault, info.PropertyType, null);
16 
17             //Getter Setter 方法标识
18             MethodAttributes getSetAttr = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig | MethodAttributes.Virtual;
19 
20             MethodBuilder getter = dynamicTypeBuilder.DefineMethod("get_" + info.Name, getSetAttr, info.PropertyType, Type.EmptyTypes);
21 
22             ILGenerator getIL = getter.GetILGenerator();
23 
24             ILGenerateProxyMethod(getIL, info.GetGetMethod(), Type.EmptyTypes, aspectAttributes);
25 
26 
27             //覆盖自动生成的Getter
28             MethodInfo getMethod = info.GetGetMethod();
29 
30             if (getMethod != null) dynamicTypeBuilder.DefineMethodOverride(getter, getMethod);
31 
32             //给属性设置Get、Set方法
33             dynamicPropertyBuilder.SetGetMethod(getter);
34 
35 
36             //重写Set 方法
37             MethodBuilder setter = dynamicTypeBuilder.DefineMethod("set_" + info.Name, getSetAttr, typeof(void), new Type[] { info.PropertyType });
38 
39             ILGenerator setIL = setter.GetILGenerator();
40 
41             ILGenerateProxyMethod(setIL, info.GetSetMethod(), new Type[] { info.PropertyType }, aspectAttributes);
42 
43 
44             //覆盖自动生成的Setter
45             MethodInfo setMethod = info.GetSetMethod();
46 
47             if (setMethod != null) dynamicTypeBuilder.DefineMethodOverride(setter, setMethod);
48 
49             dynamicPropertyBuilder.SetSetMethod(setter);
50         }

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1.1.2 重写被切入的方法 OverrideMethod

 1         /// <summary>
 2         /// 重写被代理类的指定方法
 3         /// </summary>
 4         /// <param name="typeBuilder">类型</param>
 5         /// <param name="src_Method">被代理方法</param>
 6         /// <param name="aspectAttributes">代理特性集合</param>
 7         private static void OverrideMethod(TypeBuilder typeBuilder, MethodInfo src_Method, object[] aspectAttributes)
 8         {
 9             if (aspectAttributes == null || aspectAttributes.Length == 0) return;
10 
11             MethodAttributes attr = MethodAttributes.Public | MethodAttributes.Family | MethodAttributes.HideBySig | MethodAttributes.Virtual;
12 
13             //获取当前方法参数列表
14             Type[] paramTypes = XDynamic.GetMethodParameterTypes(src_Method);
15 
16             ILGenerator il = typeBuilder.DefineMethod(src_Method.Name, attr, src_Method.ReturnType, paramTypes).GetILGenerator();
17 
18             ILGenerateProxyMethod(il, src_Method, paramTypes, aspectAttributes);
19         }

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1.1.3 生成代理方法 ILGenerateProxyMethod

 1         /// <summary>
 2         /// 
 3         /// </summary>
 4         /// <param name="il_ProxyMethod"></param>
 5         /// <param name="src_Method"></param>
 6         /// <param name="paramTypes"></param>
 7         /// <param name="aspectAttributes"></param>
 8         private static void ILGenerateProxyMethod(ILGenerator il_ProxyMethod, MethodInfo src_Method, Type[] paramTypes, object[] aspectAttributes)
 9         {
10             int aspectCount = aspectAttributes.Length;
11 
12             //生成切面上下文
13             LocalBuilder aspectContext = CreateAspectContext(il_ProxyMethod, src_Method.Name, paramTypes);
14 
15             //申明临时存放切面对象和OnExit方法的变量
16             var aspectLocalBuilders = new LocalBuilder[aspectCount];
17             var onExit_Methods = new MethodInfo[aspectCount];
18 
19 
20             //初始化标记的切面对象，并调用切面对象的OnEntry方法
21             for (int i = 0; i < aspectCount; i++)
22             {
23                 //创建一个切面对象
24                 var aspectType = aspectAttributes[i].GetType();
25                 var aspect = il_ProxyMethod.DeclareLocal(aspectType);
26                 ConstructorInfo constructor = aspectType.GetConstructor(Type.EmptyTypes);
27 
28                 il_ProxyMethod.Emit(OpCodes.Newobj, constructor);
29                 il_ProxyMethod.Emit(OpCodes.Stloc, aspect);
30 
31                 var onEntry_method = aspectType.GetMethod("OnEntry");
32                 onExit_Methods[i] = aspectType.GetMethod("OnExit");
33 
34                 //调用BeforeInvoke
35                 il_ProxyMethod.Emit(OpCodes.Ldloc, aspect);
36                 il_ProxyMethod.Emit(OpCodes.Ldloc, aspectContext);
37                 il_ProxyMethod.Emit(OpCodes.Callvirt, onEntry_method);
38                 il_ProxyMethod.Emit(OpCodes.Nop);
39 
40                 aspectLocalBuilders[i] = aspect;
41             }
42 
43             //类对象，参数值依次入栈
44             for (int i = 0; i <= paramTypes.Length; i++)
45                 il_ProxyMethod.Emit(OpCodes.Ldarg, i);
46 
47             //调用基类的方法
48             il_ProxyMethod.Emit(OpCodes.Call, src_Method);
49 
50 
51             //定义返回值
52             LocalBuilder result = null;
53 
54             //如果有返回值，保存返回值到局部变量
55             if (src_Method.ReturnType != typeof(void))
56             {
57                 result = il_ProxyMethod.DeclareLocal(src_Method.ReturnType);
58                 il_ProxyMethod.Emit(OpCodes.Stloc, result);
59 
60                 //给AspectContext的属性Result赋值
61                 var resultSetMethod = typeof(AspectContext).GetMethod("set_Result");
62                 il_ProxyMethod.Emit(OpCodes.Ldloc, aspectContext); //加载AspectContext局部变量
63                 il_ProxyMethod.Emit(OpCodes.Ldloc, result);//加载返回值
64                 il_ProxyMethod.Emit(OpCodes.Box, src_Method.ReturnType);
65                 il_ProxyMethod.Emit(OpCodes.Call, resultSetMethod);//赋值
66             }
67 
68             //调用横切对象的OnExit方法
69             for (int i = 0; i < aspectCount; i++)
70             {
71                 il_ProxyMethod.Emit(OpCodes.Ldloc, aspectLocalBuilders[i]);
72                 il_ProxyMethod.Emit(OpCodes.Ldloc, aspectContext);
73                 il_ProxyMethod.Emit(OpCodes.Callvirt, onExit_Methods[i]);
74                 il_ProxyMethod.Emit(OpCodes.Nop);
75             }
76 
77             //如果有返回值，则把返回值压栈
78             if (result != null)
79                 il_ProxyMethod.Emit(OpCodes.Ldloc, result);
80 
81             il_ProxyMethod.Emit(OpCodes.Ret);//返回
82         }

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1.1.4 生成切面上下文对象 CreateAspectContext

 1   /// <summary>
 2         /// 生成切面上下文对象
 3         /// </summary>
 4         /// <param name="il"></param>
 5         ///  <param name="methodName">方法名称</param>
 6         /// <param name="paramTypes">参数类型</param>
 7         /// <returns></returns>
 8         private static LocalBuilder CreateAspectContext(ILGenerator il, string methodName, Type[] paramTypes)
 9         {
10             //AspectContext.ParameterArgs 类型为 object[]
11 
12             //声明一个类型为object的局部数组
13             il.DeclareLocal(typeof(object[]));
14             //数组长度入栈
15             il.Emit(OpCodes.Ldc_I4, paramTypes.Length);
16             //生成新数组
17             il.Emit(OpCodes.Newarr, typeof(object));
18             //赋值给局部数组变量
19             il.Emit(OpCodes.Stloc_0);
20 
21             //遍历参数，并存入数组
22             for (int i = 0; i < paramTypes.Length; i++)
23             {
24                 il.Emit(OpCodes.Ldloc_0);//数组入栈
25                 il.Emit(OpCodes.Ldc_I4, i);//数组下标入栈
26                 il.Emit(OpCodes.Ldarg, i + 1);//按下标加载对应的参数
27                 if (paramTypes[i].IsValueType)//参数为值类型，装箱
28                     il.Emit(OpCodes.Box, paramTypes[i]);
29                 il.Emit(OpCodes.Stelem_Ref);//将参数存入数组
30             }
31 
32             //获取AspectContext构造函数
33             Type aspectContextType = typeof(AspectContext);
34             ConstructorInfo info = aspectContextType.GetConstructor(new Type[] { typeof(object), typeof(string), typeof(object[]) });
35 
36             //生成一个AspectContext 对象
37             il.Emit(OpCodes.Ldarg_0);//加载调用对象
38             il.Emit(OpCodes.Ldstr, methodName);//加载方法名称
39             il.Emit(OpCodes.Ldloc_0);//加载由参数生成的局部数组变量
40             il.Emit(OpCodes.Newobj, info);
41 
42             //声明一个AspectContext局部变量
43             LocalBuilder aspectContext = il.DeclareLocal(aspectContextType);
44             il.Emit(OpCodes.Stloc, aspectContext);
45 
46             return aspectContext;
47         }

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1.2 使用动态方法生成创建代理类型实例的委托

 1         /// <summary>
 2         /// 生成创建代理类型实例的委托
 3         /// </summary>
 4         /// <typeparam name="T">被代理类型</typeparam>
 5         /// <param name="proxyType">代理类型</param>
 6         /// <param name="parameterTypes">代理类型构造函数参数类型</param>
 7         /// <returns></returns>
 8         private static Func<object[], T> CreateFunc<T>(Type proxyType, Type[] parameterTypes)
 9         {
10             DynamicMethod method = new DynamicMethod(proxyType.Name + "_CF", typeof(T), new Type[] { typeof(object[]) }, true);
11 
12             var il = method.GetILGenerator();
13 
14             //根据T类型的构造函数参数列表，依次将 object[] parameters 中对应的值加载到堆栈（并做相应类型转换），以被T类型的构造函数使用
15             for (int i = 0; i < parameterTypes.Length; i++)
16             {
17                 
18                 il.Emit(OpCodes.Ldarg_0);
19                 il.Emit(OpCodes.Ldc_I4, i);
20                 il.Emit(OpCodes.Ldelem_Ref);
21 
22                 if (parameterTypes[i].IsValueType)
23                     // 如果是值类型，拆箱
24                     il.Emit(OpCodes.Unbox_Any, parameterTypes[i]);
25                 else
26                     // 如果是引用类型，转换
27                     il.Emit(OpCodes.Castclass, parameterTypes[i]);
28             }
29 
30             ConstructorInfo info = proxyType.GetConstructor(parameterTypes);
31 
32             if (info == null) throw new Exception("代理类不存在，与指定参数列表相对应的构造函数。");
33 
34             il.Emit(OpCodes.Newobj, info);
35             il.Emit(OpCodes.Ret);
36 
37             //建立《生成指定类型T的实例》的委托
38             return method.CreateDelegate(typeof(Func<object[], T>)) as Func<object[], T>;
39         }

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1.3 ProxyType类

 1   public class ProxyType<T>
 2     {
 3         #region 构造函数
 4         /// <summary>
 5         /// 构造函数
 6         /// </summary>
 7         /// <param name="name">类型名称</param>
 8         /// <param name="parameterSignature">构造函数参数签名</param>
 9         /// <param name="createFunc">创建被代理类型实例的委托</param>
10         public ProxyType(string name, string parameterSignature, Func<object[], T> createFunc)
11         {
12             Name = name; ParameterSignature = parameterSignature; CreateFunc = createFunc;
13         }
14         #endregion
15 
16         #region 属性
17 
18         /// <summary>
19         /// 名称
20         /// </summary>
21         public string Name { get; set; }
22 
23         /// <summary>
24         /// 参数类型签名
25         /// </summary>
26         public string ParameterSignature { get; set; }
27 
28         /// <summary>
29         /// 创建被代理类型实例的委托
30         /// </summary>
31         public Func<object[], T> CreateFunc { get; set; }
32 
33         #endregion
34     }

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  到此为止一个简单的Aop框架就完成了。下一篇会介绍一个下BuilderCollection类