C# 在配置中向Unity注册一个实例

如何在配置文件中注册实例

<register type="ICache" mapTo="CacheMng">
    <lifetime type="Singleton"/>
    <constructor>
        <param name="cache" type="System.Web.Caching" value="HttpRuntime.Cache"/>
    </constructor>>
</register>

我有以下代码：

UnityContainer.RegisterInstance<ICache>(new CacheMng(HttpRuntime.Cache));

我犯了这个错误

无法解析类型名称或别名System.Web.Caching

---

您看到错误消息的原因是

type

参数需要类型名称，而不是名称空间名称

System.Web.Caching

是一个名称空间，而不是一种类型

唯一的方法是编写一个自定义类型转换器并使用

value

元素，如下所示：

<constructor>
    <param name="cache">
        <value value="" typeConverter="MyHttpRuntimeCacheConverter" />
    </param>
</constructor>

---

您可以通过实际为Unity

value

元素提供一个值（例如：

System.Web.HttpRuntime.Cache

）使其更普遍适用根据这个值，让类型转换器返回正确的对象。

根据前面的答案，我想到了创建一个类型转换器来访问任何静态属性的想法。以下是我的实现：

namespace EntLibUnity.UnitySample
{
    public class VersionManager : IVersionManager
    {
        private readonly Version _version;

        public string Version
        {
            get { return _version.ToString(); }
        }

        public VersionManager(Version version)
        {
            _version = version;
        }
    }
}

namespace EntLibUnity.Infrastructure
{
    public interface IVersionManager
    {
        string Version { get; }
    }
}

类型转换器实现

using System;
using System.ComponentModel;
using System.Reflection;

namespace EntLibUnity.Extensions
{
    /// <summary>
    /// Converts an (formatted) string to a reference of a given static member.
    /// The string uses this format: {member}@{assemblyQualifiedName}
    /// For example:
    ///     Version@System.Environment, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
    /// </summary>
    public class StringToStaticInstanceTypeConverter : TypeConverter
    {
        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
        {
            return (typeof(string) == sourceType) || base.CanConvertFrom(context, sourceType);
        }

        public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
        {
            string stringValue;
            if (value == null
                || (stringValue = value as string) == null
                || string.IsNullOrEmpty(stringValue)
                || !stringValue.Contains("@")
            )
            {
                return null;
            }

            var stringParts = stringValue.Split('@');
            if (stringParts.Length != 2)
            {
                return null;
            }
            var staticProperty = stringParts[0];
            var assemblyQualifiedName = stringParts[1];
            var staticClassType = Type.GetType(assemblyQualifiedName, true);
            var staticPropertyInfo = staticClassType.GetProperty(staticProperty,
                                                                 BindingFlags.Public | BindingFlags.Static |
                                                                 BindingFlags.FlattenHierarchy);
            var staticValue = staticPropertyInfo.GetValue(null, null) ?? base.ConvertFrom(context, culture, value);
            return staticValue;
        }
    }
}

我们的具体版本取决于System.version，所以我们配置容器来提供这个值。在我的示例中，我将为此使用配置文件

<?xml version="1.0" encoding="utf-8" ?>
<unity xmlns="http://schemas.microsoft.com/practices/2010/unity">
  <!-- Using Design-Time Configuration: http://msdn.microsoft.com/en-us/library/ff660935(v=PandP.20).aspx#format_config -->
  <!-- The Unity Configuration Schema: http://msdn.microsoft.com/en-us/library/ff660914(v=PandP.20).aspx -->
  <!-- Specifying Types in the Configuration File http://msdn.microsoft.com/en-us/library/ff660933(v=PandP.20).aspx#_Default_Aliases_and-->

  <alias alias="StringToStaticInstanceTypeConverter" type="EntLibUnity.Extensions.StringToStaticInstanceTypeConverter, EntLibUnity.Extensions" />
  <alias alias="IVersionManager" type="EntLibUnity.Infrastructure.IVersionManager, EntLibUnity.Infrastructure" />
  <alias alias="VersionManager" type="EntLibUnity.UnitySample.VersionManager, EntLibUnity.UnitySample" />

  <container>
    <register type="IVersionManager" mapTo="VersionManager">
      <constructor>
        <param name="version">
          <value value="Version@System.Environment, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" typeConverter="StringToStaticInstanceTypeConverter" />
        </param>
      </constructor>
    </register>
  </container>

</unity>

最后，加载配置后，您可以按如下方式使用：

var versionManager = container.Resolve<IVersionManager>();
Console.WriteLine(versionManager.Version);

var versionManager=container.Resolve（）；
WriteLine（versionManager.Version）；

祝你好运

<?xml version="1.0" encoding="utf-8" ?>
<unity xmlns="http://schemas.microsoft.com/practices/2010/unity">
  <!-- Using Design-Time Configuration: http://msdn.microsoft.com/en-us/library/ff660935(v=PandP.20).aspx#format_config -->
  <!-- The Unity Configuration Schema: http://msdn.microsoft.com/en-us/library/ff660914(v=PandP.20).aspx -->
  <!-- Specifying Types in the Configuration File http://msdn.microsoft.com/en-us/library/ff660933(v=PandP.20).aspx#_Default_Aliases_and-->

  <alias alias="StringToStaticInstanceTypeConverter" type="EntLibUnity.Extensions.StringToStaticInstanceTypeConverter, EntLibUnity.Extensions" />
  <alias alias="IVersionManager" type="EntLibUnity.Infrastructure.IVersionManager, EntLibUnity.Infrastructure" />
  <alias alias="VersionManager" type="EntLibUnity.UnitySample.VersionManager, EntLibUnity.UnitySample" />

  <container>
    <register type="IVersionManager" mapTo="VersionManager">
      <constructor>
        <param name="version">
          <value value="Version@System.Environment, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" typeConverter="StringToStaticInstanceTypeConverter" />
        </param>
      </constructor>
    </register>
  </container>

</unity>

var versionManager = container.Resolve<IVersionManager>();
Console.WriteLine(versionManager.Version);