团结 - loadConfiguration，如何解决只有那些配置 [英] Unity - loadConfiguration, how to resolve only those configured

问题描述

我想实现：具有单位从配置文件加载的映射，然后在源代码中解决这是从上述配置文件

What I am trying to achieve: Have Unity load the mappings from a configuration file, then in source code resolve the types which were loaded from said configuration file

应用程序加载的类型.CONFIG

App.Config

<register type="NameSpace.ITill, ExampleTightCoupled" mapTo="NameSpace.Till, NameSpace" />
<register type="NameSpace.IAnalyticLogs, NameSpace" mapTo="NameSpace.AnalyticLogs, NameSpace" />

代码

Code

IUnityContainer container;
container = new UnityContainer();

// Read interface->type mappings from app.config
container.LoadConfiguration();

// Resolve ILogger - this works
ILogger obj = container.Resolve<ILogger>();

// Resolve IBus - this fails
IBus = container.Resolve<IBus>();

问题：有时下iBus将在App.config中定义的，有时它会不会在那里。当我尝试解决一个接口/类，它不存在，我得到一个异常。

Issue: Sometimes IBus will be defined in the App.config, and sometimes it will not be there. When I try and resolve an interface/class and it does not exist I get an exception.

有人能教我吗？

谢谢，
安德鲁

Thanks, Andrew

推荐答案

您正在使用什么版本的Unity？在V2 +有一个扩展方法：

What version of Unity are you using? In v2+ there is an extension method:

public static bool IsRegistered<T>(this IUnityContainer container);

所以你可以做

so you can do

if (container.IsRegistered<IBus>())
    IBus = container.Resolve<IBus>();

这是扩展方法将使这更好

An extension method would make this nicer

public static class UnityExtensions
{
    public static T TryResolve<T>(this IUnityContainer container)
    {
        if (container.IsRegistered<T>())
            return container.Resolve<T>();

        return default(T);
    }
}

// TryResolve returns the default type (null in this case) if the type is not configured
IBus = container.TryResolve<IBus>();

另外，请查阅此链接：是否有TryResolve在Unity？

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