.net 动态代理的泛型方法支持问题

Posted 2020-06-12

    最近一直在做.net平台下的高速服务框架。其中有一个问题一直困扰着我：通过动态代理RealProxy创建的服务代理，不支持泛型方法调用。比如：

接口声明：

public interface IMetedataService
{
    string GetData<T>(T p);

    string GetDataWithHSF<T>(T p);
}

接口实现：

public class EventMetadataService:IMetedataService
   {
       public string GetData<T>(T p)
       {
           javascriptSerializer ser = new JavaScriptSerializer();
           return ser.Serialize(p);
       }

       public string GetDataWithHSF<T>(T p)
       {
           JavaScriptSerializer ser = new JavaScriptSerializer();
           string data = ser.Serialize(p);

           string getdata = HSFService.Proxy<IMetedataService>().GetData<string>(DateTime.Now.ToLongTimeString());
           return getdata + " " + data;

       }
   }

    EventMetadataService被部署到HSF的Container中。在HSF的Consumer端，调用代码如下。此代码在执行时会出现异常：不能对containsgenericparameters为true的类型或方法执行后期绑定操作

EventData dd = new EventData();
            dd.ID = Guid.NewGuid().ToString();
            dd.Code = "Good boy";
            dd.Names = data;
            List<EventData> res = new List<EventData>();
            res.Add(dd);

            var result = HSFService.Proxy<IMetedataService>().GetData<List<EventData>>(res);

    在HSFService中，通过动态代理远程调用HSF的Container服务。重载了RealProxy，其的核心代码如下：

public override IMessage Invoke(IMessage msg)
        {
          
            DateTime start = DateTime.Now;
            RemoteInvokeMessage requestMessage = null;
            var message = msg as IMethodCallMessage;
            if (message == null)
            {
                return null;
            }

            try
            {
                requestMessage = new RemoteInvokeMessage
                {
                    ServiceClassName = typeof(TProxy).FullName,
                    MethodName = message.MethodName,
                    Parameters = message.InArgs,
                    Version = this._serviceVersion,
                    Properties = new System.Collections.Generic.Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
                };

                var responseMessage = tcpClient.SendMessageAndWaitForResponse(requestMessage) as RemoteInvokeReturnMessage;
                if (responseMessage == null)
                {
                    return null;
                }

                if (responseMessage.RemoteException != null)
                {
                  return new ReturnMessage(responseMessage.RemoteException, message);

                }
                else
                {
                    return new ReturnMessage(responseMessage.ReturnValue, null, 0, message.LogicalCallContext, message);
                }
            }
            catch (Exception ex)
            {
                return new ReturnMessage(ex, message);
            }
        }
    }

  为了解决上述异常，修改了RealProxy的Invoke代码，并在RemoteInvokeMessage中加入了记录泛型方法的属性：

public string[] GenericTypes { get; set; }

　Invoke方法的代码更新如下：

public override IMessage Invoke(IMessage msg)
        {
          
            DateTime start = DateTime.Now;
            RemoteInvokeMessage requestMessage = null;
            var message = msg as IMethodCallMessage;
            if (message == null)
            {
                return null;
            }

            try
            {
                requestMessage = new RemoteInvokeMessage
                {
                    ServiceClassName = typeof(TProxy).FullName,
                    MethodName = message.MethodName,
                    Parameters = message.InArgs,
                    Version = this._serviceVersion,
                    Properties = new System.Collections.Generic.Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
                };

        if (message.MethodBase!= null && message.MethodBase.IsGenericMethod)
                {
                    var tps= message.MethodBase.GetGenericArguments();
                    if (tps != null)
                    {
                        List<string> strTypes = new List<string>();
                       
                        foreach (var item in tps)
                        {
                            strTypes.Add(JsonConvert.SerializeObject(item));
                        }

                        requestMessage.GenericTypes = strTypes.ToArray();
                    }
                }

                var responseMessage = tcpClient.SendMessageAndWaitForResponse(requestMessage) as RemoteInvokeReturnMessage;
                if (responseMessage == null)
                {
                    return null;
                }

                if (responseMessage.RemoteException != null)
                {
                  return new ReturnMessage(responseMessage.RemoteException, message);

                }
                else
                {
                    return new ReturnMessage(responseMessage.ReturnValue, null, 0, message.LogicalCallContext, message);
                }
            }
            catch (Exception ex)
            {
                return new ReturnMessage(ex, message);
            }
        }
    }

　　上面标记代码，主要是提取了泛型方法的类型。只要把类型传递到HSF Container中，就可反射加载相关类型，并在反射调用方法时，通过MakeGenericMethod方法设置泛型类型，从而解决异常“不能对containsgenericparameters为true的类型或方法执行后期绑定操作”。

MethodInfo m = null;
           if (methodMap.ContainsKey(methodName) == true)
           {
               if (methodMap.TryGetValue(methodName, out m) == false)
                   m = InternalGetMethod(typeName, methodName, m, arg);
           }
           else
               m = InternalGetMethod(typeName, methodName, m, arg);

           if (m.IsGenericMethod)
           {
               List<Type> typs = new List<Type>();
               if (message.GenericTypes != null)
               {
                   foreach (string item in message.GenericTypes)
                   {
                       typs.Add(GetDataType(item));
                   }
               }
               m = m.MakeGenericMethod(typs.ToArray());
           }

    顺便说一句，HSF Container拿到泛型方法的类型后，需要转换为Type类型对象，这里也有很多的问题和技巧，贴一下我的解决方案把。

private Type GetDataType(string item)
        {
            string asmName = string.Empty;
            string tName = string.Empty;

            var citem = item.Replace("\"", "");

            Type result = Type.GetType(citem, false, true);
            if (result != null)
                return result;
            if (result == null)
                result = Type.ReflectionOnlyGetType(citem, false, true);
            if (result != null)
                return result;

            throw new HSFException(ErrorCode.InvalideParam, "无法找到类型：" + item);

        }

    一定要确保类型对应的程序集已经被加载。

 

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