我开始与Unity进行越来越多的工作。我注意到Resolver方法采用了params参数ResolverOverride。
有人可以给我一个例子,说明我如何使用ResolverOverride或为我提供一些其他信息,以获取更多线索。
Answers:
如您所知,这是Unity 2的一项新功能(非常酷)。
有 ParameterOverride : ResolverOverride
ResolverOverride类,使您可以重写传递给构造函数的命名参数。
DependencyOverride : ResolverOverride
一个类,只要有给定类型的依赖项,它就会覆盖注入的值,无论它在对象图中的位置如何。
PropertyOverride : ResolverOverride
ResolverOverride,使您可以覆盖指定属性的值。
例
using System;
using Microsoft.Practices.Unity;
namespace ConsoleApplication1 {
class Program {
static void Main(string[] args) {
var container = new UnityContainer();
//ParameterOverride example
container.RegisterType<IConcreteService, ConcreteService>(
new InjectionConstructor(7) //Old way to pass value to constructor - not flexible.
//All resolved (without override which appears only in unity 2.0) classes will have val=7
);
var service0 = container.Resolve<IConcreteService>();
Console.WriteLine(service0.Val); //prints 7
var service = container.Resolve<IConcreteService>(new ParameterOverride("val", 3));
Console.WriteLine(service.Val); // prints 3
var service2 = container.Resolve<IConcreteService>(new ParameterOverride("val", 5));
Console.WriteLine(service2.Val); // prints 5
Console.ReadLine();
//DependencyOverride example
var b0 = container.Resolve<B>(new DependencyOverride<IConcreteService>(new ConcreteService(42)));
Console.WriteLine(b0.Service.Val); //print 42
Console.WriteLine(b0.Service1.Val); //print 42
var b = container.Resolve<B>(new DependencyOverride<IConcreteService>(new ConcreteService(-42)));
Console.WriteLine(b.Service.Val); // print -42
Console.WriteLine(b.Service1.Val); // print -42
Console.ReadLine();
//PropertyOverride example
var b1 = container.Resolve<B>(new PropertyOverride("Service", new ConcreteService(42)),
new PropertyOverride("Service1", new ConcreteService(-42)));
Console.WriteLine(b1.Service.Val); //print 42
Console.WriteLine(b1.Service1.Val); //print -42
Console.ReadLine();
}
}
public interface IConcreteService {
int Val { get; set; }
}
public class ConcreteService : IConcreteService {
public int Val { get; set; }
public ConcreteService(int val) {
Val = val;
}
}
public class B {
[Dependency]
public IConcreteService Service{ get; set; }
[Dependency]
public IConcreteService Service1 { get; set; }
}
}
不知道Google为什么对此保持沉默。
引号来自Unity源代码xml文档。
以防万一有人感兴趣,我做了一个扩展方法,使解析语法使用起来ParameterOverride
更容易阅读。方法如下:
public static class UnityExtensions
{
public static T Resolve<T>(this IUnityContainer container, object parameterOverrides)
{
var properties = parameterOverrides
.GetType()
.GetProperties(BindingFlags.Public | BindingFlags.Instance);
var overridesArray = properties
.Select(p => new ParameterOverride(p.Name, p.GetValue(parameterOverrides, null)))
.Cast<ResolverOverride>()
.ToArray();
return container.Resolve<T>(null, overridesArray); //null needed to avoid a StackOverflow :)
}
}
这样,您可以重写ParameterOverride示例,如下所示:
var service = container.Resolve<IConcreteService>(new {val=3});
我希望这对某人有用...