Unity 使用配置文件

和所有的 IOC 框架一样，我们可以使用 XML 文件来配置 Unity。个人建议你使用一个单独的 XML 配置文件，因为 app.config/web.config 已经被塞入太多的东西，早已臃肿不堪。修改配置的时候既不清晰，也容易出错。

Unity.xml

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="unity"
         type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,
         Microsoft.Practices.Unity.Configuration, Version=1.0.0.0, Culture=neutral,
         PublicKeyToken=31bf3856ad364e35" />
  </configSections>
  <unity>
    <typeAliases>
      <typeAlias alias="singleton" type="Microsoft.Practices.Unity.ContainerControlledLifetimeManager,
                 Microsoft.Practices.Unity" />
      <typeAlias alias="Data" type="Learn.CUI.Data, Learn.CUI" />
      <typeAlias alias="ICache" type="Learn.CUI.ICache, Learn.CUI" />
      <typeAlias alias="MemoryCache" type="Learn.CUI.MemoryCache, Learn.CUI" />
      <typeAlias alias="FileCache" type="Learn.CUI.FileCache, Learn.CUI" />
    </typeAliases>
    <containers>
      <container name="global">
        <types>
          <type type="Data" mapTo="Data">
            <lifetime type="singleton" />
          </type>
          
          <type name="memory" type="ICache" mapTo="MemoryCache" />
          
          <type name="file" type="ICache" mapTo="FileCache">
            <typeConfig extensionType="Microsoft.Practices.Unity.Configuration.TypeInjectionElement,
                  Microsoft.Practices.Unity.Configuration">
              <constructor>
                <param name="data" parameterType="Data">
                  <dependency />
                </param>
                <param name="s" parameterType="System.String">
                  <value value="Hello, World!" />
                </param>
              </constructor>
              <property name="Data" propertyType="Data" />
              <method name="Initialize">
                <param name="data" parameterType="Data">
                  <dependency />
                </param>
                <param name="s" parameterType="System.String">
                  <value value="Who..." />
                </param>
              </method>
            </typeConfig>
          </type>
        </types>
        <instances>
        </instances>
      </container>
    </containers>
  </unity>
</configuration>

test.cs

public class Data { }

public interface ICache { }

public class MemoryCache : ICache { }

public class FileCache : ICache
{
  [InjectionConstructor]
  public FileCache(Data data, string s)
  {
    Console.WriteLine("--Injection Constructor--");
    Console.WriteLine("data != null? {0}", data != null);
    Console.WriteLine("s = {0}", s);
  }

  private Data data;

  [Dependency]
  public Data Data
  {
    get
    {
      return data;
    }
    set
    {
      data = value;

      Console.WriteLine("--Injection Property--");
      Console.WriteLine("this.Data != null? {0}", data != null);
    }
  }

  [InjectionMethod]
  public void Initialize(Data data, string s)
  {
    Console.WriteLine("--Injection Method--");
    Console.WriteLine("data != null? {0}", data != null);
    Console.WriteLine("s = {0}", s);
  }
}

class Program
{
  static void Main(string[] args)
  {
    var configMap = new ExeConfigurationFileMap { ExeConfigFilename = "Unity.xml" };
    var configuration = ConfigurationManager.OpenMappedExeConfiguration(configMap,
         ConfigurationUserLevel.None);
    var section = (UnityConfigurationSection)configuration.GetSection("unity");

    var container = new UnityContainer();
    section.Containers["global"].Configure(container);

    // --- test ---

    var file = container.Resolve<ICache>("file");
  }
}

编写配置文件和读取配置的代码都不算太复杂，其自带的帮助文件也有详细的解释，我就不多废话了。
尽管有别名机制可以减少工作量和出错几率，但还是希望能提供一个图形化的管理工具，否则每次都得反反复复翻看手册，太麻烦。