我想使用Castle Windsor在WebApi应用程序中实现依赖注入。我有以下示例代码-
界面 -
public interface IWatch
{
{
DateTime GetTime();
}
}
以下Watch类实现IWatch接口-
public class Watch:IWatch
{
public DateTime GetTime()
{
return DateTime.Now;
}
}
WebApi控制器-WatchController如下-
public class WatchController : ApiController
{
private readonly IWatch _watch;
public WatchController()
{
_watch = new Watch();
}
//http://localhost:48036/api/Watch
public string Get()
{
var message = string.Format("The current time on the server is: {0}", _watch.GetTime());
return message;
}
}
目前,我正在用WatchController构造函数中的Watch初始化IWatch对象。我想删除使用Windsor Castle依赖注入原理在构造函数内部初始化IWatch的依赖。
在WebApi的情况下,有人可以为我提供实现依赖注入的步骤吗?提前致谢!
CodeCaster,Noctis和Cristiano感谢您的所有帮助和指导。.我刚刚得到了上述查询的解决方案-
第一步是使用nuget在WebApi解决方案中安装Windsor.Castle软件包。
考虑以下代码片段-
接口IWatch.cs
public interface IWatch
{
DateTime GetTime();
}
Watch.cs类
public class Watch:IWatch
{
public DateTime GetTime()
{
return DateTime.Now;
}
}
ApiController WatchController.cs的定义如下:-
public class WatchController : ApiController
{
private readonly IWatch _watch;
public WatchController(IWatch watch)
{
_watch = watch;
}
public string Get()
{
var message = string.Format("The current time on the server is: {0}", _watch.GetTime());
return message;
}
}
在控制器中,我们通过WatchController构造函数中的IWatch对象注入了依赖项。我已经使用IDependencyResolver和IDependencyScope在Web api中实现依赖注入。IDependencyResolver接口用于解析请求范围之外的所有内容。
WindsorDependencyResolver.cs
internal sealed class WindsorDependencyResolver : IDependencyResolver
{
private readonly IWindsorContainer _container;
public WindsorDependencyResolver(IWindsorContainer container)
{
if (container == null)
{
throw new ArgumentNullException("container");
}
_container = container;
}
public object GetService(Type t)
{
return _container.Kernel.HasComponent(t) ? _container.Resolve(t) : null;
}
public IEnumerable<object> GetServices(Type t)
{
return _container.ResolveAll(t).Cast<object>().ToArray();
}
public IDependencyScope BeginScope()
{
return new WindsorDependencyScope(_container);
}
public void Dispose()
{
}
}
WindsorDependencyScope.cs
internal sealed class WindsorDependencyScope : IDependencyScope
{
private readonly IWindsorContainer _container;
private readonly IDisposable _scope;
public WindsorDependencyScope(IWindsorContainer container)
{
if (container == null)
{
throw new ArgumentNullException("container");
}
_container = container;
_scope = container.BeginScope();
}
public object GetService(Type t)
{
return _container.Kernel.HasComponent(t) ? _container.Resolve(t) : null;
}
public IEnumerable<object> GetServices(Type t)
{
return _container.ResolveAll(t).Cast<object>().ToArray();
}
public void Dispose()
{
_scope.Dispose();
}
}
WatchInstaller.cs
安装程序只是实现IWindsorInstaller接口的简单类型。该接口具有一个称为Install的单一方法。该方法获取容器的实例,然后可以使用流利的注册API来注册组件:
public class WatchInstaller : IWindsorInstaller
{
public void Install(IWindsorContainer container, IConfigurationStore store)
{
//Need to Register controllers explicitly in your container
//Failing to do so Will receive Exception:
//> An error occurred when trying to create //a controller of type
//> 'xxxxController'. Make sure that the controller has a parameterless
//> public constructor.
//Reason::Basically, what happened is that you didn't register your controllers explicitly in your container.
//Windsor tries to resolve unregistered concrete types for you, but because it can't resolve it (caused by an error in your configuration), it return null.
//It is forced to return null, because Web API forces it to do so due to the IDependencyResolver contract.
//Since Windsor returns null, Web API will try to create the controller itself, but since it doesn't have a default constructor it will throw the "Make sure that the controller has a parameterless public constructor" exception.
//This exception message is misleading and doesn't explain the real cause.
container.Register(Classes.FromThisAssembly()
.BasedOn<IHttpController>()
.LifestylePerWebRequest());***
container.Register(
Component.For<IWatch>().ImplementedBy<Watch>()
);
}
}
最后,我们需要用Global.asax.cs中的Windsor实现替换默认的依赖项解析器(Application_Start方法),并安装我们的依赖项:
private static IWindsorContainer _container;
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
WebApiConfig.Register(GlobalConfiguration.Configuration);
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
ConfigureWindsor(GlobalConfiguration.Configuration);
}
public static void ConfigureWindsor(HttpConfiguration configuration)
{
_container = new WindsorContainer();
_container.Install(FromAssembly.This());
_container.Kernel.Resolver.AddSubResolver(new CollectionResolver(_container.Kernel, true));
var dependencyResolver = new WindsorDependencyResolver(_container);
configuration.DependencyResolver = dependencyResolver;
}
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