我正在使用Unity版本2.1.505.2并在注册带有默认注册的UnityContainer和相同接口类型的命名注册(使用ParameterOverride)时看到意外行为.
如果我调用container.Resolve< T>()两次 – 一次用于命名注册,一次用于默认注册 – 我得到相同的实例,而我期望基于两个不同注册的不同实例.
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,以便调用container.Resolve< ICage>(“cage2”)返回对应两个命名注册的Cage实例,并调用container.Resolve< ICage>()返回对应的实例默认注册?
最佳答案 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”.
你打电话的时候:
var cage2 = container.Resolve<ICage>("cage2");
你跑:
new InjectionFactory(c => c.Resolve<Cage>(new ParameterOverride("animal", new Dog()))));
看看内部c.Resolve< Cage>,当它调用unity创建的对象Cage时,新的Dog()作为IAnimal.但!以上,您注册的类型:
container.RegisterType<ICage, Cage>(new ContainerControlledLifetimeManager());
所以!内部c.Resolve< Cage>使用Dog创建对象Cage的无命名注册.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
}
}