MVC TIP8：为控制器增加有参构造函数（为了注入等其它用途）

控制器本身是不带有参的构造函数的，如果我们为控制器仅仅提供有参的构造函数，就会报错。不过，可以利用DependencyResolver的SetResolver方法，让ASP.NET MVC支持有参的构造函数。

1：为系统准备两个类型，如下：

注意，这里要实现的是让控制器支持Unity注入。

UnityControllerFactory代码如下：

public class UnityControllerFactory : DefaultControllerFactory
{
    IUnityContainer container;
    public UnityControllerFactory(IUnityContainer container)
    {
        this.container = container;
    }
 
    protected override IController GetControllerInstance(RequestContext reqContext,
        Type controllerType)
    {
        if (controllerType == null)
        {
            return null;
        }
        return container.Resolve(controllerType) as IController;
    }
}

UnityDependencyResolver代码如下：

public class UnityDependencyResolver : IDependencyResolver
{
    IUnityContainer container;
 
    public UnityDependencyResolver(IUnityContainer container)
    {
        this.container = container;
    }
 
    public object GetService(Type serviceType)
    {
        if (!this.container.IsRegistered(serviceType))
        {
            return null;
        }
        return container.Resolve(serviceType);
    }
 
    public IEnumerable<object> GetServices(Type serviceType)
    {
        return container.ResolveAll(serviceType);
    }
}

2：在Application_Start中注册

代码如下：

using (IUnityContainer container = new UnityContainer())
{
    UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity");
    section.Configure(container, "containerOne");
    //tell mvc use UnityDependencyResolver to create controll instances;
    container.RegisterType<IControllerFactory, UnityControllerFactory>();
    //_container.RegisterType<ISubjectRepository, SubjectRepository>(new TransientLifetimeManager());
    DependencyResolver.SetResolver(new UnityDependencyResolver(container));
}

3：Web.config配置如下

<configSections>
  <section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,Microsoft.Practices.Unity.Configuration"/>
</configSections>
 
<unity xmlns="http://schemas.microsoft.com/practices/2010/unity">
  <assembly name="SampleProject"/>
  <namespace name="SampleProject"/>
 
  <alias alias="ISampleClass" type="ISampleClass" />
  <alias alias="SampleClass" type="SampleClass" />
 
  <container name="containerOne">
    <register type="ISampleClass" mapTo="SampleClass" />
  </container>
 
</unity>