AutoFac使用方法总结二
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2022-03-26 22:54:18
事件 AutoFac支持三种事件:OnActivating,OnActivated,OnRelease。OnActivating在注册组件使用之前会被调用,此时可以替换实现类或者进行一些其他的初始化工作,OnActivated在实例化之后会被调用,OnRelease在组件释放之后会被调用。 此时的输 ......
事件
AutoFac支持三种事件:OnActivating,OnActivated,OnRelease。OnActivating在注册组件使用之前会被调用,此时可以替换实现类或者进行一些其他的初始化工作,OnActivated在实例化之后会被调用,OnRelease在组件释放之后会被调用。
1 public class MyEvent : IDisposable 2 { 3 public MyEvent(string input) 4 { 5 Console.WriteLine(input); 6 } 7 8 public MyEvent() 9 { 10 Console.WriteLine("Init"); 11 } 12 13 public void Dispose() 14 { 15 Console.WriteLine("Dispose"); 16 } 17 }
1 public void test_event() 2 { 3 var builder = new ContainerBuilder(); 4 builder.RegisterType<MyEvent>(). 5 OnActivating(e => e.ReplaceInstance(new MyEvent("input"))). 6 OnActivated(e => Console.WriteLine("OnActivated")). 7 OnRelease(e => Console.WriteLine("OnRelease")); 8 9 10 using (IContainer container = builder.Build()) 11 { 12 using (var myEvent = container.Resolve<MyEvent>()) 13 { 14 } 15 } 16 }
此时的输出为:
1 Init 2 input 3 OnActivated 4 Dispose 5 OnRelease
利用事件可以在构造对象之后调用对象的方法:
1 [Fact] 2 public void call_method_when_init() 3 { 4 var builder = new ContainerBuilder(); 5 builder.RegisterType<MyClassWithMethod>().OnActivating(e => e.Instance.Add(5)); 6 IContainer container = builder.Build(); 7 Assert.Equal(5, container.Resolve<MyClassWithMethod>().Index); 8 } 9 10 public class MyClassWithMethod 11 { 12 public int Index { get; set; } 13 public void Add(int value) 14 { 15 Index = Index + value; 16 } 17 }
循环依赖
循环依赖是个比较头疼的问题,在AutoFac中很多循环依赖的场景不被支持:
1 public class ClassA 2 { 3 private readonly ClassB b; 4 5 public ClassA(ClassB b) 6 { 7 this.b = b; 8 } 9 } 10 11 public class ClassB 12 { 13 public ClassA A { get; set; } 14 15 } 16 17 [Fact] 18 public void circular_dependencies_exception() 19 { 20 var builder = new ContainerBuilder(); 21 builder.Register(c => new ClassB(){A = c.Resolve<ClassA>()}); 22 builder.Register(c => new ClassA(c.Resolve<ClassB>())); 23 IContainer container = builder.Build(); 24 Assert.Throws(typeof(DependencyResolutionException), ()=>container.Resolve<ClassA>()); 25 }
可以部分的解决这种循环依赖的问题,前提是ClassA和ClassB的生命周期不能都是InstancePerDependency
1 [Fact] 2 public void circular_dependencies_ok() 3 { 4 var builder = new ContainerBuilder(); 5 builder.RegisterType<ClassB>(). 6 PropertiesAutowired(PropertyWiringFlags.AllowCircularDependencies).SingleInstance(); 7 builder.Register(c => new ClassA(c.Resolve<ClassB>())); 8 IContainer container = builder.Build(); 9 Assert.NotNull(container.Resolve<ClassA>()); 10 Assert.NotNull(container.Resolve<ClassB>()); 11 Assert.NotNull(container.Resolve<ClassB>().A); 12 }
转载链接:http://niuyi.github.io/blog/2012/04/06/autofac-by-unit-test-2/
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