c# - 在配置文件中动态注入(inject)基于关闭值的 WCF ServiceContract 的具体实现

Question

假设我有以下服务契约和两个具体实现:

[OperationContract]
public interface ISearchService {
    public ICollection<string> Search(string text);
}

[SearchServiceBehaviour]
public class SolrSearchService : ISearchService {
    public ICollection<string> Search(string text) {
        // Implementation...
    }
}

[SearchServiceBehaviour]
public class SqlSearchService : ISearchService {
    public ICollection<string> Search(string text) {
        // Implementation...
    }
}

这些都带有 ServiceBehavior 属性，因此我可以在服务运行时根据配置文件创建实例:

public class SearchServiceBehaviour : Attribute, IServiceBehavior {
    public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase) {
        foreach (var item in serviceHostBase.ChannelDispatchers) {
            var dispatcher = item as ChannelDispatcher;

            if (dispatcher != null) {
                dispatcher.Endpoints.ToList().ForEach(e => {
                    e.DispatchRuntime.InstanceProvider = new SearchServiceInstanceProvider();
                });
            }
        }
    }
}

public class SearchServiceInstanceProvider : IInstanceProvider {
    public object GetInstance(InstanceContext instanceContext, Message message) {
        // Should cache and only do this at an interval.
        ConfigurationManager.RefreshSection("appSettings");
        var index = ConfigurationManager.AppSettings["UseSolr"] as string;

        bool UseSolr;
        bool.TryParse(index, out UseSolr);

        if (UseSolr)
            return new IndexedSearchService();
        else
            return new SearchService();
    }
}

我的问题是如何根据配置文件中不断变化的值使用 Ninject 注入(inject)具体实现？看来我应该做以下事情:

public class SearchServiceModule : NinjectModule {
    private bool UseSolr;

    public SearchServiceModule() {
        // Should cache and only do this at an interval.
        ConfigurationManager.RefreshSection("appSettings");
        var index = ConfigurationManager.AppSettings["UseSolr"] as string;

        bool.TryParse(index, out UseSolr);
    }

    public override Load() {
        if (UseSolr)
            Bind<ISearchService>().To<SolrSearchService>();
        else 
            Bind<ISearchService>().To<SqlSearchService>();
    }
}

然后在 InstanceProvider 中:

public object GetInstance(InstanceContext instanceContext, Message message) {
    return _kernel.Get<ISearchService>();
}

但是，在我更改配置文件中的值后，Ninject 中的绑定(bind)不会更改。有没有办法根据配置文件中的值更改绑定(bind)？我在这里做错了什么吗？

Answer 1

您的模块没有像您预期的那样运行，因为有一个字段和一个同名的局部变量。

另请参阅条件绑定(bind)。 .When()