实现WCF和Unity 的集成
Artech 已经写过一篇[原创]WCF后续之旅（7）：通过WCF Extension实现和Enterprise Library Unity Container的集成，在这个解决方案中Unity的侵入性有点强，本文介绍一种具有更少的侵入性的解决方案。
第一步：创建一个自定义的InstanceProvider 来处理WCF服务。
InstanceProvider就是用于创建或者提供service instance的。除了提供service instance的创建者或者提供者的身份外，InstanceProvider还用于service instance的释放和回收。所有的IntanceProvider实现了System.ServiceModel.Dispatcher.IInstanceProvider 接口：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Practices.Unity;
using System.ServiceModel.Dispatcher;
using System.ServiceModel;
using System.ServiceModel.Channels;
namespace Tencent.OA.Framework.ServiceModel
{
public class UnityInstanceProvider : IInstanceProvider
{
public UnityContainer Container { set; get; }
public Type ServiceType { set; get; }
public UnityInstanceProvider()
: this(null)
{
}
public UnityInstanceProvider(Type type)
{
ServiceType = type;
Container = new UnityContainer();
}
#region IInstanceProvider Members
public object GetInstance(InstanceContext instanceContext, Message message)
{
return Container.Resolve(ServiceType);
}
public object GetInstance(InstanceContext instanceContext)
{
return GetInstance(instanceContext, null);
}
public void ReleaseInstance(InstanceContext instanceContext, object instance)
{
}
#endregion
}
} 可以看到GetInstance方法用来获取服务实例，通过Unity的Resolve方法解析。
第二步：创建UnityInstanceProvider对应的Behavior
第一步已经创建了自定义的UnityInstanceProvider，现在需要在运行时插入我们这个新的Provider，这项工作可以通过IServiceProvider（定义一种检索服务对象的机制，服务对象是为其他对象提供自定义支持的对象）来完成。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel.Dispatcher;
using System.ServiceModel.Description;
using System.ServiceModel;
using System.Collections.ObjectModel;
using System.ServiceModel.Channels;
using Microsoft.Practices.Unity;
namespace Tencent.OA.Framework.ServiceModel
{
public class UnityServiceBehavior : IServiceBehavior
{
public UnityInstanceProvider InstanceProvider
{ get; set; }
private ServiceHost serviceHost = null;
public UnityServiceBehavior()
{
InstanceProvider = new UnityInstanceProvider();
}
public UnityServiceBehavior(UnityContainer unity)
{
InstanceProvider = new UnityInstanceProvider();
InstanceProvider.Container = unity;
}
public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
{
foreach (ChannelDispatcherBase cdb in serviceHostBase.ChannelDispatchers)
{
ChannelDispatcher cd = cdb as ChannelDispatcher;
if (cd != null)
{
foreach (EndpointDispatcher ed in cd.Endpoints)
{
InstanceProvider.ServiceType = serviceDescription.ServiceType;
ed.DispatchRuntime.InstanceProvider = InstanceProvider;
}
}
}
}
public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
{ }
public void AddBindingParameters(ServiceDescription serviceDescription,ServiceHostBase serviceHostBase,Collection<ServiceEndpoint> endpoints,
BindingParameterCollection bindingParameters)
{
}
}
} 当调用ApplyDispatchBehaviour，代码通过循环收集在我们的项目Endpoints，并传递给相应的服务类型的InstanceProvider。
第三步：创建自定义的增加新的Behavior的 Service Host
ServiceHost 提供了基本的“加载服务，配置endpoints，应用安全设置以及启动监听请求”机制。通过自定义一个ServiceHost将我们自己的Behavior添加进去。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;
using Microsoft.Practices.Unity;
namespace Tencent.OA.Framework.ServiceModel
{
public class UnityServiceHost : ServiceHost
{
public UnityContainer Container { set; get; }
public UnityServiceHost()
: base()
{
Container = new UnityContainer();
}
public UnityServiceHost(Type serviceType, params Uri[] baseAddresses)
: base(serviceType, baseAddresses)
{
Container = new UnityContainer();
}
protected override void OnOpening()
{
if (this.Description.Behaviors.Find<UnityServiceBehavior>() == null)
this.Description.Behaviors.Add(new UnityServiceBehavior(Container));
base.OnOpening();
}
}
} 当Service Host启动的时候，它就会检查我们的UnityServiceBehavior是否已经添加到Behaviors里面，如果没有就把它加入到Behaviors集合。
第四步：创建自定义的ServiceHostFactory
如果只是承载在Console Application、Windows Service或者其他非Web应用程序，我们的工作已经完成了。但在Web的.svc中，ServiceHost是动态创建的，没有显示的指定ServiceHost的Factory,那它在默认情况下是使用ServiceHostFactory的，而ServiceHostFactory产生的是ServiceHost对象，想要使用我们上一步中自定义的UnityServiceHost ，需要实现一个自定义的ServcieHostFactory,实现代码非常简单：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Practices.Unity.Configuration;
using Microsoft.Practices.Unity;
using System.ServiceModel.Activation;
using System.ServiceModel;
using System.Configuration;
namespace Tencent.OA.Framework.ServiceModel
{
public class UnityServiceHostFactory : ServiceHostFactory
{
protected override ServiceHost CreateServiceHost(
Type serviceType, Uri[] baseAddresses)
{
UnityServiceHost serviceHost = new UnityServiceHost(serviceType, baseAddresses);
UnityContainer container = new UnityContainer();
serviceHost.Container = container;
//configure container
UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity");
section.Containers.Default.Configure(serviceHost.Container);
return serviceHost;
}
}
}