我使用Unity版本2.1.505.2并在注册UnityContainer
时使用默认注册和命名注册(使用ParameterOverride
)查看相同的接口类型时出现意外行为。
如果我两次调用container.Resolve<T>()
- 一次用于命名注册,一次用于默认注册 - 我得到相同的实例,而我期望基于两种不同的注册实例。
这是一个代码示例:
public interface ICage
{
IAnimal Animal { get; }
}
public class Cage : ICage
{
public IAnimal Animal { get; private set; }
public Cage(IAnimal animal) { Animal = animal; }
}
public interface IAnimal
{
string Species { get; }
}
public class Cat : IAnimal
{
public string Species { get { return "Felis catus"; } }
}
public class Dog : IAnimal
{
public string Species { get { return "Canis lupus"; } }
}
[TestClass]
public class UnityTest
{
[TestMethod]
public void MyTest()
{
var container = new UnityContainer();
// Default registrations for IAnimal and ICage
container.RegisterType<IAnimal, Cat>(new ContainerControlledLifetimeManager());
container.RegisterType<ICage, Cage>(new ContainerControlledLifetimeManager());
// Named registration "cage2" for ICage mapping to Cage with constructor parameter override
container.RegisterType<ICage>(
"cage2",
new ContainerControlledLifetimeManager(),
new InjectionFactory(c => c.Resolve<Cage>(new ParameterOverride("animal", new Dog()))));
// Resolve ICage using the named registraion "cage2"
var cage2 = container.Resolve<ICage>("cage2");
Assert.AreEqual("Canis lupus", cage2.Animal.Species); // Assert succeeds
// Resolve ICage using the default registration ???
var cage = container.Resolve<ICage>();
Assert.AreEqual("Felis catus", cage.Animal.Species); // Assert fails (Actual:<Canis lupus>)
}
}
测试中的第二个断言失败,因为cage.Animal.Species
返回"Canis lupus"
。
我错过了我的理解吗?如何进行设置以便对container.Resolve<ICage>("cage2")
的调用返回与命名注册相对应的Cage
实例,并且对container.Resolve<ICage>()
的调用将返回与默认注册相对应的实例?
答案 0 :(得分:1)
我花了2天时间解决你的问题,我已经知道了!
问题在于命名注册“cage2”。
致电时:
var cage2 = container.Resolve<ICage>("cage2");
你跑:
new InjectionFactory(c => c.Resolve<Cage>(new ParameterOverride("animal", new Dog()))));
查看内部c.Resolve<Cage>
,当它调用unity创建的对象Cage
时new Dog()
为IAnimal。但!上面,您注册了类型:
container.RegisterType<ICage, Cage>(new ContainerControlledLifetimeManager());
原来如此!内部c.Resolve<Cage>
使用Cage
为对象Dog
创建无命名注册。并且,当它注册为ContainerControlled时,它保存值,并在您调用时:
var cage = container.Resolve<ICage>();
你得到了价值,已经创造了!
固定解决方案:
[TestClass]
public class UnityTest
{
[TestMethod]
public void MyTest()
{
var container = new UnityContainer();
// Default registrations for IAnimal and ICage
container.RegisterType<IAnimal, Cat>(new ContainerControlledLifetimeManager());
container.RegisterType<ICage, Cage>(new ContainerControlledLifetimeManager());
container.RegisterType<ICage>(
"cage2",
new ContainerControlledLifetimeManager(),
new InjectionFactory(c => new Cage(new Dog())));
// Resolve ICage using the named registraion "cage2"
var cage2 = container.Resolve<ICage>("cage2");
Assert.AreEqual("Canis lupus", cage2.Animal.Species); // Assert succeeds
// Resolve default
var cage = container.Resolve<ICage>();
Assert.AreEqual("Felis catus", cage.Animal.Species); // Assert succeeds
}
}