** 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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