WCF 使用动态代理精简代码架构

使用Castle.Core.dll实现，核心代码是使用Castle.DynamicProxy.ProxyGenerator类的CreateInterfaceProxyWithoutTarget方法动态创建代理对象

NuGet上面Castle.Core的下载量1.78亿之多

一、重构前的项目代码

    重构前的项目代码共7层代码，其中WCF服务端3层，WCF接口层1层，客户端3层，共7层

    1.服务端WCF服务层SunCreate.InfoPlatform.Server.Service

    2.服务端数据库访问接口层SunCreate.InfoPlatform.Server.Bussiness

    3.服务端数据库访问实现层SunCreate.InfoPlatform.Server.Bussiness.Impl

    4.WCF接口层SunCreate.InfoPlatform.Contract

    5.客户端代理层SunCreate.InfoPlatform.Client.Proxy

    6.客户端业务接口层SunCreate.InfoPlatform.Client.Bussiness

    7.客户端业务实现层SunCreate.InfoPlatform.Client.Bussiness.Impl

二、客户端通过动态代理重构

    1.实现在拦截器中添加Ticket、处理异常、Close对象

    2.客户端不需要再写代理层代码，而使用动态代理层

    3.对于简单的增删改查业务功能，也不需要再写业务接口层和业务实现层，直接调用动态代理；对于复杂的业务功能以及缓存，才需要写业务接口层和业务实现层

客户端动态代理工厂类ProxyFactory代码(该代码目前写在客户端业务实现层)：

using Castle.DynamicProxy;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.Text;
using System.Threading.Tasks;

namespace SunCreate.InfoPlatform.Client.Bussiness.Imp
{
    /// <summary>
    /// WCF服务工厂
    /// PF是ProxyFactory的简写
    /// </summary>
    public class PF
    {
        /// <summary>
        /// 拦截器缓存
        /// </summary>
        private static ConcurrentDictionary<Type, IInterceptor> _interceptors = new ConcurrentDictionary<Type, IInterceptor>();

        /// <summary>
        /// 代理对象缓存
        /// </summary>
        private static ConcurrentDictionary<Type, object> _objs = new ConcurrentDictionary<Type, object>();

        private static ProxyGenerator _proxyGenerator = new ProxyGenerator();

        /// <summary>
        /// 获取WCF服务
        /// </summary>
        /// <typeparam name="T">WCF接口</typeparam>
        public static T Get<T>()
        {
            Type interfaceType = typeof(T);

            IInterceptor interceptor = _interceptors.GetOrAdd(interfaceType, type =>
            {
                string serviceName = interfaceType.Name.Substring(1); //服务名称
                ChannelFactory<T> channelFactory = new ChannelFactory<T>(serviceName);
                return new ProxyInterceptor<T>(channelFactory);
            });

            return (T)_objs.GetOrAdd(interfaceType, type => _proxyGenerator.CreateInterfaceProxyWithoutTarget(interfaceType, interceptor)); //根据接口类型动态创建代理对象，接口没有实现类
        }
    }
}

客户端拦截器类ProxyInterceptor<T>代码(该代码目前写在客户端业务实现层)：

using Castle.DynamicProxy;
using log4net;
using SunCreate.Common.Base;
using SunCreate.InfoPlatform.Client.Bussiness;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.Text;
using System.Threading.Tasks;

namespace SunCreate.InfoPlatform.Client.Bussiness.Imp
{
    /// <summary>
    /// 拦截器
    /// </summary>
    /// <typeparam name="T">接口</typeparam>
    public class ProxyInterceptor<T> : IInterceptor
    {
        private static ILog _log = LogManager.GetLogger(typeof(ProxyInterceptor<T>));

        private ChannelFactory<T> _channelFactory;

        public ProxyInterceptor(ChannelFactory<T> channelFactory)
        {
            _channelFactory = channelFactory;
        }

        /// <summary>
        /// 拦截方法
        /// </summary>
        public void Intercept(IInvocation invocation)
        {
            //准备参数
            ParameterInfo[] parameterInfoArr = invocation.Method.GetParameters();
            object[] valArr = new object[parameterInfoArr.Length];
            for (int i = 0; i < parameterInfoArr.Length; i++)
            {
                valArr[i] = invocation.GetArgumentValue(i);
            }

            //执行方法
            T server = _channelFactory.CreateChannel();
            using (OperationContextScope scope = new OperationContextScope(server as IContextChannel))
            {
                try
                {
                    HI.Get<ISecurityBussiness>().AddTicket();

                    invocation.ReturnValue = invocation.Method.Invoke(server, valArr);

                    var value = HI.Get<ISecurityBussiness>().GetValue();
                    ((IChannel)server).Close();
                }
                catch (Exception ex)
                {
                    _log.Error("ProxyInterceptor " + typeof(T).Name + " " + invocation.Method.Name + " 异常", ex);
                    ((IChannel)server).Abort();
                }
            }

            //out和ref参数处理
            for (int i = 0; i < parameterInfoArr.Length; i++)
            {
                ParameterInfo paramInfo = parameterInfoArr[i];
                if (paramInfo.IsOut || paramInfo.ParameterType.IsByRef)
                {
                    invocation.SetArgumentValue(i, valArr[i]);
                }
            }
        }
    }
}

如何使用：

List<EscortTask> list = PF.Get<IBussDataService>().GetEscortTaskList();

这里不用再写try catch，异常在拦截器中处理

三、WCF服务端通过动态代理，在拦截器中校验Ticket、处理异常

服务端动态代理工厂类ProxyFactory代码(代码中保存动态代理dll不是必需的)：

using Autofac;
using Castle.DynamicProxy;
using Castle.DynamicProxy.Generators;
using SunCreate.Common.Base;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.ServiceModel;
using System.ServiceModel.Activation;
using System.Text;
using System.Threading.Tasks;

namespace SunCreate.InfoPlatform.WinService
{
    /// <summary>
    /// 动态代理工厂
    /// </summary>
    public class ProxyFactory
    {
        /// <summary>
        /// 拦截器缓存
        /// </summary>
        private static ConcurrentDictionary<Type, IInterceptor> _interceptors = new ConcurrentDictionary<Type, IInterceptor>();

        /// <summary>
        /// 代理对象缓存
        /// </summary>
        private static ConcurrentDictionary<Type, object> _objs = new ConcurrentDictionary<Type, object>();

        private static ProxyGenerator _proxyGenerator;

        private static ModuleScope _scope;

        private static ProxyGenerationOptions _options;

        static ProxyFactory()
        {
            AttributesToAvoidReplicating.Add(typeof(ServiceContractAttribute)); //动态代理类不继承接口的ServiceContractAttribute

            String path = AppDomain.CurrentDomain.BaseDirectory;

            _scope = new ModuleScope(true, false,
                ModuleScope.DEFAULT_ASSEMBLY_NAME,
                Path.Combine(path, ModuleScope.DEFAULT_FILE_NAME),
                "MyDynamicProxy.Proxies",
                Path.Combine(path, "MyDymamicProxy.Proxies.dll"));
            var builder = new DefaultProxyBuilder(_scope);

            _options = new ProxyGenerationOptions();

            //给动态代理类添加AspNetCompatibilityRequirementsAttribute属性
            PropertyInfo proInfoAspNet = typeof(AspNetCompatibilityRequirementsAttribute).GetProperty("RequirementsMode");
            CustomAttributeInfo customAttributeInfo = new CustomAttributeInfo(typeof(AspNetCompatibilityRequirementsAttribute).GetConstructor(new Type[0]), new object[0], new PropertyInfo[] { proInfoAspNet }, new object[] { AspNetCompatibilityRequirementsMode.Allowed });
            _options.AdditionalAttributes.Add(customAttributeInfo);

            //给动态代理类添加ServiceBehaviorAttribute属性
            PropertyInfo proInfoInstanceContextMode = typeof(ServiceBehaviorAttribute).GetProperty("InstanceContextMode");
            PropertyInfo proInfoConcurrencyMode = typeof(ServiceBehaviorAttribute).GetProperty("ConcurrencyMode");
            customAttributeInfo = new CustomAttributeInfo(typeof(ServiceBehaviorAttribute).GetConstructor(new Type[0]), new object[0], new PropertyInfo[] { proInfoInstanceContextMode, proInfoConcurrencyMode }, new object[] { InstanceContextMode.Single, ConcurrencyMode.Multiple });
            _options.AdditionalAttributes.Add(customAttributeInfo);

            _proxyGenerator = new ProxyGenerator(builder);
        }

        /// <summary>
        /// 动态创建代理
        /// </summary>
        public static object CreateProxy(Type contractInterfaceType, Type impInterfaceType)
        {
            IInterceptor interceptor = _interceptors.GetOrAdd(impInterfaceType, type =>
            {
                object _impl = HI.Provider.GetService(impInterfaceType);
                return new ProxyInterceptor(_impl);
            });

            return _objs.GetOrAdd(contractInterfaceType, type => _proxyGenerator.CreateInterfaceProxyWithoutTarget(contractInterfaceType, _options, interceptor)); //根据接口类型动态创建代理对象，接口没有实现类
        }

        /// <summary>
        /// 保存动态代理dll
        /// </summary>
        public static void Save()
        {
            string filePath = Path.Combine(_scope.WeakNamedModuleDirectory, _scope.WeakNamedModuleName);
            if (File.Exists(filePath))
            {
                File.Delete(filePath);
            }
            _scope.SaveAssembly(false);
        }
    }
}

说明：object _impl = HI.Provider.GetService(impInterfaceType); 这句代码用于创建数据库访问层对象，HI是项目中的一个工具类，类似Autofac框架的功能

服务端拦截器类ProxyInterceptor<T>代码：

using Castle.DynamicProxy;
using log4net;
using SunCreate.Common.Base;
using SunCreate.InfoPlatform.Server.Bussiness;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.Text;
using System.Threading.Tasks;

namespace SunCreate.InfoPlatform.WinService
{
    /// <summary>
    /// 拦截器
    /// </summary>
    public class ProxyInterceptor : IInterceptor
    {
        private static ILog _log = LogManager.GetLogger(typeof(ProxyInterceptor));

        private object _impl;

        public ProxyInterceptor(object impl)
        {
            _impl = impl;
        }

        /// <summary>
        /// 拦截方法
        /// </summary>
        public void Intercept(IInvocation invocation)
        {
            //准备参数
            ParameterInfo[] parameterInfoArr = invocation.Method.GetParameters();
            object[] valArr = new object[parameterInfoArr.Length];
            for (int i = 0; i < parameterInfoArr.Length; i++)
            {
                valArr[i] = invocation.GetArgumentValue(i);
            }

            //执行方法
            try
            {
                if (HI.Get<ISecurityImp>().CheckTicket())
                {
                    Type implType = _impl.GetType();
                    MethodInfo methodInfo = implType.GetMethod(invocation.Method.Name);
                    invocation.ReturnValue = methodInfo.Invoke(_impl, valArr);
                }
            }
            catch (Exception ex)
            {
                _log.Error("ProxyInterceptor " + invocation.TargetType.Name + " " + invocation.Method.Name + " 异常", ex);
            }

            //out和ref参数处理
            for (int i = 0; i < parameterInfoArr.Length; i++)
            {
                ParameterInfo paramInfo = parameterInfoArr[i];
                if (paramInfo.IsOut || paramInfo.ParameterType.IsByRef)
                {
                    invocation.SetArgumentValue(i, valArr[i]);
                }
            }
        }
    }
}

服务端WCF的ServiceHost工厂类：

using Spring.ServiceModel.Activation;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.ServiceModel;
using System.Text;
using System.Threading.Tasks;

namespace SunCreate.InfoPlatform.WinService
{
    public class MyServiceHostFactory : ServiceHostFactory
    {
        public MyServiceHostFactory() { }

        public override ServiceHostBase CreateServiceHost(string reference, Uri[] baseAddresses)
        {
            Assembly contractAssembly = Assembly.GetAssembly(typeof(SunCreate.InfoPlatform.Contract.IBaseDataService));
            Assembly impAssembly = Assembly.GetAssembly(typeof(SunCreate.InfoPlatform.Server.Bussiness.IBaseDataImp));
            Type contractInterfaceType = contractAssembly.GetType("SunCreate.InfoPlatform.Contract.I" + reference);
            Type impInterfaceType = impAssembly.GetType("SunCreate.InfoPlatform.Server.Bussiness.I" + reference.Replace("Service", "Imp"));
            if (contractInterfaceType != null && impInterfaceType != null)
            {
                var proxy = ProxyFactory.CreateProxy(contractInterfaceType, impInterfaceType);
                ServiceHostBase host = new ServiceHost(proxy, baseAddresses);
                return host;
            }
            else
            {
                return null;
            }
        }
    }
}

svc文件配置ServiceHost工厂类：

<%@ ServiceHost Language="C#" Debug="true"  Service="BaseDataService"  Factory="SunCreate.InfoPlatform.WinService.MyServiceHostFactory" %>

如何使用自定义的ServiceHost工厂类启动WCF服务，下面是部分代码：

MyServiceHostFactory factory = new MyServiceHostFactory();
List<ServiceHostBase> hostList = new List<ServiceHostBase>();
foreach (var oFile in dirInfo.GetFiles())
{
    try
    {
        string strSerName = oFile.Name.Replace(oFile.Extension, "");
        string strUrl = string.Format(m_strBaseUrl, m_serverPort, oFile.Name);
        var host = factory.CreateServiceHost(strSerName, new Uri[] { new Uri(strUrl) });
        if (host != null)
        {
            hostList.Add(host);
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine("出现异常：" + ex.Message);
        m_log.ErrorFormat(ex.Message + ex.StackTrace);
    }
}
ProxyFactory.Save();
foreach (var host in hostList)
{
    try
    {
        foreach (var endpoint in host.Description.Endpoints)
        {
            endpoint.EndpointBehaviors.Add(new MyEndPointBehavior()); //用于添加消息拦截器、全局异常拦截器
        }
        host.Open();
        m_lsHost.TryAdd(host);
    }
    catch (Exception ex)
    {
        Console.WriteLine("出现异常：" + ex.Message);
        m_log.ErrorFormat(ex.Message + ex.StackTrace);
    }
}

WCF服务端再也不用写Service层了 

四、当我需要添加一个WCF接口，以实现一个查询功能，比如查询所有组织机构，重构前，我需要在7层添加代码，然后客户端调用，重构后，我只需要在3层添加代码，然后客户端调用

    1.在WCF接口层添加接口

    2.在服务端数据访问接口层添加接口

    3.在服务端数据访问实现层添加实现方法

    4.客户端调用：var orgList = PF.Get<IBaseDataService>().GetOrgList();

    重构前，需要在7层添加代码，虽然每层代码都差不多，可以复制粘贴，但是复制粘贴也很麻烦啊，重构后省事多了，从此再也不怕写增删改查了

五、性能损失

主要是invocation.Method.Invoke比直接调用慢，耗时是直接调用的2、3倍，但是多花费的时间跟数据库查询耗时比起来，是微不足道的