c# – Unity配置和嵌套泛型类型

2019年8月3日 201次阅读

我是Unity的新手,在WCF服务中遇到配置和嵌套泛型类型的问题.一切都工作正常,直到我遇到需要定义工厂的情况,该工厂返回基于通用接口的类型实例.

代码看起来像这样：

public interface IFactory<T, TResult>
{
    TResult CreateInstance(T input);
}

public interface IFilter<T>
{
    // throws an exception if an item is to be filtered
    void Filter(T itemToFilter);
}

// classes implementing this interface can have multiple filters    
public interface IFilterRunner<T>
{        
    void RunFilters(T itemToFilter);
}

public class FilterRunnerFactory : IFactory<BaseType, IFilterRunner<BaseType>>
{
    public IFilterRunner<BaseType> CreateInstance(BaseType input)
    {
        if (input is SubType)
        {
            return new SubTypeFilterRunner();
        }

        throw new InvalidOperationException("Could not create an IFilterRunner for the input.");
    }
}

public class Service
{
    private readonly IFactory<BaseType, IFilterRunner<BaseType>> _filterRunnerFactory;

    public Service(IFactory<BaseType, IFilterRunner<BaseType>> filterRunnerFactory)
    {
        _filterRunnerFactory = filterRunnerFactory;
    }    
}

Unity配置看起来像这样：

<unity xmlns="http://schemas.microsoft.com/practices/2010/unity">
  <alias alias="BaseType" type="SomeNamespace.BaseType, SomeAssembly, Version=1.0.0.0, Culture=neutral" />
  <alias alias="IFactory" type="SomeNamespace.IFactory`2, SomeAssembly, Version=1.0.0.0, Culture=neutral" />
  <alias alias="IFilterRunner" type="SomeNamespace.IFilterRunner`1, SomeAssembly, Version=1.0.0.0, Culture=neutral" />
  <alias alias="IService" type="SomeNamespace.IService, SomeAssembly, Version=1.0.0.0, Culture=neutral" /> 
  <containers>
    <container>
      <register type="IFactory[BaseType,IFilterRunner]" mapTo="SomeNamespace.FilterRunnerFactory, SomeAssembly, Version=1.0.0.0, Culture=neutral"/>

      <register type="IService" mapTo="SomeNamespace.Service, SomeAssembly, Version=1.0.0.0, Culture=neutral">
        <constructor>
          <param name="filterRunnerFactory" />
        </constructor>
      </register>
    </container>
  </containers>
</unity>

配置似乎有效但是当WCF服务本身被实例化时,我收到以下错误：

InvalidOperationException – The
current type,
SomeNamespace.IFactory2[SomeNamespace.BaseType,SomeNamespace.IFilterRunner1[SomeNamespace.BaseType]],
is an interface and cannot be
constructed. Are you missing a type
mapping?

我尝试过各种不同的选项,但都会导致配置无效.此外,我还有其他工厂定义被定义为返回抽象基类型或基于非泛型接口的类型实例,并且它们工作正常.不同之处在于该工厂返回IFilterRunner – 一个通用接口.

有没有人有什么建议？提前感谢困惑的开发人员.

最佳答案 我通过为IFilterRunner的别名指定通用参数来修复您的问题.

<unity xmlns="http://schemas.microsoft.com/practices/2010/unity">
  <alias alias="BaseType" type="SomeNamespace.BaseType, SomeAssembly, Version=1.0.0.0, Culture=neutral" />
  <alias alias="IFactory" type="SomeNamespace.IFactory`2, SomeAssembly, Version=1.0.0.0, Culture=neutral" />
  <alias alias="IFilterRunner" type="SomeNamespace.IFilterRunner`1[[SomeNamespace.BaseType, SomeAssembly, Version=1.0.0.0, Culture=neutral]], SomeAssembly, Version=1.0.0.0, Culture=neutral" />
  <alias alias="IService" type="SomeNamespace.IService, SomeAssembly, Version=1.0.0.0, Culture=neutral" />
  <containers>
    <container>
      <register type="IFactory[BaseType,IFilterRunner]" mapTo="SomeNamespace.FilterRunnerFactory, SomeAssembly, Version=1.0.0.0, Culture=neutral"/>

      <register type="IService" mapTo="SomeNamespace.Service, SomeAssembly, Version=1.0.0.0, Culture=neutral">
        <constructor>
          <param name="filterRunnerFactory" />
        </constructor>
      </register>
    </container>
  </containers>
</unity>
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