SharpDevelop中Addin插件系统的详解(一)

** SharpDevelop 中 Addin 插件系统的 详解(一) **

相信会有很多的 Programmer 们对换“插件”这一术语都会抱有很大的兴趣,而 #SharpDevelopr 中的插件系统正以它较大的灵活性、可扩展性吸引了从多 Programmer 的目光。

(关于 #SharpDevelop 源码,可以去 http://sourceforge.com 下载。)

1. 服务概念与 Addin 插件系统的结合

在剖析 Addin 插件系统之前,我们还是要首先来了解一下 #SharpDevelop 中的 Service (服务)概念,这也正是基于 #SharpDevelop 的 Addin 插件系统与 Service 服务紧密结合所作出一种考虑。

在剖析 Addin 插件系统之前,我们还是要首先来了解一下 #SharpDevelop 中的 Service (服务)概念,这也正是基于 #SharpDevelop 的 Addin 插件系统与 Service 服务紧密结合所作出一种考虑。

#SharpDevelop 中的服务,是指用于提供一些诸如“ OpenFile ”功能的类。在 #SharpDevelop 中,为了保证这些服务类的可替换性、可扩展性以及服务类的简单定位功能,引入了用于管理这些服务类的 ServiceManager 类。由于该 ServiceManager 类采用了 Singleton 设计模式,从而保证了在 #SharpDevelop 的任一部分均可方便地获取、使用这些服务类。

以下为与服务概念相关的一些源码,读者可从 SharpDevelop\src\Main\Core\Services 、 SharpDevelop\src\Main\Base\Services 中获取。

////////////////////////////////////////////////////////////////////////////////////////////////////////////////

public class ServiceManager

{

ArrayList serviceList = new ArrayList();

Hashtable servicesHashtable = new Hashtable();

// Singleton design pattern.

static ServiceManager defaultServiceManager = new ServiceManager();

///

1<summary>
2
3///  Gets the default ServiceManager 
4
5///  </summary>

public static ServiceManager Services

{

Get { return defaultServiceManager; }

}

///

1<summary>
2
3///  Don't create ServiceManager objects, only have ONE per application. 
4
5///  </summary>

private ServiceManager()

{

// add 'core' services

AddService( new PropertyService());

AddService( new StringParserService());

AddService( new FileUtilityService());

}

///

1<remarks>
2
3///  This method initializes the service system to a path inside the add-in tree. 
4
5///  This method must be called ONCE. 
6
7///  </remarks>

public void InitializeServicesSubsystem( string servicesPath)

{

// add add-in tree services

AddServices((IService[])AddInTreeSingleton.AddInTree.GetTreeNodeservicesPath).BuildChildItems( this ).ToArray( typeof (IService)));

// initialize all services

foreach (IService service in serviceList)

{

DateTime now = DateTime.Now;

service.InitializeService();

}

}

///

1<remarks>
2
3///  Calls UnloadService on all services. This method must be called ONCE. 
4
5///  </remarks>

public void UnloadAllServices()

{

foreach (IService service in serviceList)

{

service.UnloadService();

}

}

public void AddService(IService service)

{

serviceList.Add(service);

}

public void AddServices(IService[] services)

{

foreach (IService service in services)

{

AddService(service);

}

}

// HACK: MONO BUGFIX

// this doesn't work on mono:serviceType.IsInstanceOfType(service)

bool IsInstanceOfType(Type type, IService service)

{

Type serviceType = service.GetType();

foreach (Type iface in serviceType.GetInterfaces())

{

if (iface == type)

{

return true ;

}

}

while (serviceType != typeof (System.Object))

{

if (type == serviceType)

{

return true ;

}

serviceType = serviceType.BaseType;

}

return false ;

}

///

1<remarks>
2
3///  Requestes a specific service, may return null if this service is not found. 
4
5///  </remarks>

public IService GetService(Type serviceType)

{

IService s = (IService)servicesHashtable[serviceType];

if (s != null )

{

return s;

}

foreach (IService service in serviceList)

{

if (IsInstanceOfType(serviceType, service))

{

servicesHashtable[serviceType] = service;

return service;

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