使用反射(Reflection)實現應用程式擴充元件機制

    public IHost Host
    {
        get
        {
            return _host;
        }
        set
        {
            _host = value;
        }
    }

    public PlugInController(IHost host)
    {
        this.Host = host;
    }

    IModule GetModule(Assembly asm, string fullTypeName)
    {
        Type t = asm.GetType(fullTypeName);
        IModule module = null;
        if (!(t.IsNotPublic || t.IsAbstract))
        {
            object objInterface = t.GetInterface("IModule", true);

            if (objInterface != null)
            {
                module = asm.CreateInstance(t.FullName) as IModule;
                module.Host = Host;
                return module;
            }
        }
        return null;
    }

    IModule GetModule(Assembly asm, Type moduleType)
    {
        return GetModule(asm, moduleType.FullName);
    }

    public IModule[] GetModules(Assembly asm)
    {
        List<IModule> modules = new List<IModule>();
        IModule module = null;
        foreach (Type t in asm.GetTypes())
        {
            module = GetModule(asm, t);

            if (module != null)
                modules.Add(module);
        }
        return modules.ToArray ();
    }

    public IModule[] GetModules(string assemblyFile)
    {
        if (!File.Exists(assemblyFile))
            throw new FileNotFoundException();
        return GetModules(Assembly.LoadFile(assemblyFile));
    }

    public IModule[] GetModulesFromDirectory(string directoryPath)
    {
        List<IModule> modules = new List<IModule>();
        foreach (string file in Directory.GetFiles(directoryPath,"*.dll"))
            modules.AddRange (GetModules(file));
        return modules.ToArray ();
    }
}</pre>

    protected Form m_View 
    {
        get
        {
            if (_view == null)
                _view = new MainForm() { MdiParent = Host as Form };
            return _view;
        }
    }


    #region IModule 成員

    public string Name
    {
        get
        {
            return "SubModule";
        }
    }

    public IHost Host
    {
        get
        {
            return _host;
        }
        set
        {
            _host = value;
        }
    }

    public  void Execute()
    {            
        m_View.Show();
    }

    #endregion
}</pre>

    void Module_Click(object sender, EventArgs e)
    {
        ((sender as ToolStripMenuItem).Tag as IModule).Execute();
    }

   ...

    #region IHost 成員

    private PlugInController _plugInAgent;

    public PlugInController PlugInAgent
    {
        get 
        {
            if (_plugInAgent == null)
                _plugInAgent = new PlugInController(this);
            return _plugInAgent; 
        }
    }

    #endregion
}</pre>

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