.NET Core类库System.Reflection.DispatchProxy实现简易Aop的方法_实用技巧_

 class Program { static void Main(string[] args) { //创建代理类，并把SampleProxy作为拦截器注入 var sampleProxy = (targetInterface)SampleProxy.Create(); //执行接口方法 sampleProxy.Write("here is invoke by proxy"); } } //需要被生成代理实例的接口 public interface targetInterface { //这个方法会被代理类实现 void Write(string writesomeshing); } public class SampleProxy : DispatchProxy { /// 
 /// 拦截调用 /// 
 /// 所拦截的方法信息 /// 所拦截方法被传入的参数指 ///  protected override object Invoke(MethodInfo targetMethod, object[] args) { Console.WriteLine(args[0]); return null; } }

 /// 
 /// 拦截器接口 /// 
 public interface IInterceptor { /// 
 /// 拦截器调用 /// 
 /// 代理实例 /// 所拦截的方法 /// 所拦截方法传入的参数值 /// 返回值会传递给方法返回值 object Intercept(object target, MethodInfo method, object[] parameters); }

 public class ProxyGenerator : DispatchProxy { private IInterceptor interceptor { get; set; } /// 
 /// 创建代理实例 /// 
 /// 所要代理的接口类型 /// 拦截器 /// 代理实例 public static object Create(Type targetType, IInterceptor interceptor) { object proxy = GetProxy(targetType); ((ProxyGenerator)proxy).CreateInstance(interceptor); return proxy; } /// 
 /// 创建代理实例 /// 
 /// 所要代理的接口类型 /// 拦截器类型 /// 拦截器构造函数参数值 /// 代理实例 public static object Create(Type targetType, Type interceptorType, params object[] parameters) { object proxy = GetProxy(targetType); ((ProxyGenerator)proxy).CreateInstance(interceptorType, parameters); return proxy; } /// 
 /// 创建代理实例 TTarget:所要代理的接口类型 TInterceptor:拦截器类型 /// 
 /// 拦截器构造函数参数值 /// 代理实例 public static TTarget Create(params object[] parameters) where TInterceptor : IInterceptor { var proxy = GetProxy(typeof(TTarget)); ((ProxyGenerator)proxy).CreateInstance(typeof(TInterceptor), parameters); return (TTarget)proxy; } private static object GetProxy(Type targetType) { var callexp = Expression.Call(typeof(DispatchProxy), nameof(DispatchProxy.Create), new[] { targetType, typeof(ProxyGenerator) }); return Expression.Lambda>(callexp).Compile()(); } private void CreateInstance(Type interceptorType, object[] parameters) { var ctorParams = parameters.Select(x => x.GetType()).ToArray(); var paramsExp = parameters.Select(x => Expression.Constant(x)); var newExp = Expression.New(interceptorType.GetConstructor(ctorParams), paramsExp); this.interceptor = Expression.Lambda>(newExp).Compile()(); } private void CreateInstance(IInterceptor interceptor) { this.interceptor = interceptor; } protected override object Invoke(MethodInfo method, object[] parameters) { return this.interceptor.Intercept(method, parameters); } }

 class Program { static void Main(string[] args) { var poxy1 = (targetInterface)ProxyGenerator.Create(typeof(targetInterface), new SampleProxy("coreproxy1")); poxy1.Write("here was invoked"); //---> "here was invoked by coreproxy1" var poxy2 = (targetInterface)ProxyGenerator.Create(typeof(targetInterface), typeof(SampleProxy), "coreproxy2"); poxy2.Write("here was invoked"); //---> "here was invoked by coreproxy2" var poxy3 = ProxyGenerator.Create("coreproxy3"); poxy3.Write("here was invoked"); //---> "here was invoked by coreproxy3" } } public class SampleProxy : IInterceptor { private string proxyName { get; } public SampleProxy(string name) { this.proxyName = name; } public object Intercept(MethodInfo method, object[] parameters) { Console.WriteLine(parameters[0] + " by " + proxyName); return null; } } public interface targetInterface { void Write(string writesome); }