Delphi 基本插件框架

我必须为我正在开发的非gui应用程序开发插件系统。我设想这是一个核心应用程序，它有一套基本的功能，并且可以通过插件进行扩展

现在，我发现最好的方法可能是将插件制作成DLL，并在主机应用程序中加载它们。插件应该能够修改appcore的某些部分（访问某些方法/变量），这是一个棘手的部分

我的想法是创建

THost

类，它实现

IHost

和

IHostExposed

接口。当主机加载插件时，它会将

IHostExposed

传递给插件，插件可以调用方法/访问该接口中的变量。大概是这样的：

接口声明：

unit uHostInterfaces;

interface

type
  IHost = interface
  ['{BAFA98BC-271A-4847-80CE-969377C03966}']
    procedure Start;
    procedure Stop;
  end;

  // this intf will get exposed to plugin
  IHostExposed = interface 
  ['{1C59B1A9-EC7A-4D33-A574-96DF8F5A7857}']
    function GetVar1: Integer;
    function GetVar2: String;

    procedure SetVar1(const AValue: Integer);
    procedure SetVar2(const AValue: String);

    property Var1: Integer read GetVar1 write SetVar1;
    property Var2: String read GetVar2 write SetVar2;
  end;

implementation

end.

unit uHost;

interface

uses
  Winapi.Windows, Winapi.Messages,
  uHostInterfaces, uInstanceController, uSettings;

type
  THost = class(TInterfacedObject, IHost, IHostExposed)
  private
    FVar1              : Integer;
    FVar2              : String;

    FWindowHandle      : HWND;
    FInstanceController: TInstanceController;
    FSettings          : TSettings;

    procedure WndProc(var AMessage: TMessage);

  public
    constructor Create;
    destructor Destroy; override;

    // methods from IHost
    procedure Start;
    procedure Stop;

    // methods from IHostExposed, which get set Var1/Var2
    function GetVar1: Integer;
    function GetVar2: string;

    procedure SetVar1(const AValue: Integer);
    procedure SetVar2(const AValue: string);
  end;

  implementation

  ...

type
  TRegisterPlugin = procedure(const AHostExposed: IHostExposed);

var
  hdll          : THandle;
  RegisterPlugin: TRegisterPlugin;
  host          : IHost;

begin
  host := THost.Create;

  hdll := LoadLibrary('plugin.dll');
  if hdll <> 0 then
  begin
    @RegisterPlugin := GetProcAddress(hdll, 'RegisterPlugin');
    if Assigned(RegisterPlugin) then
    begin
      // call the plugin function and pass IHostExposed interface to it
      // from there on, plugin can use this interface to interact with core app
      RegisterPlugin(host as IHostExposed); 

      ...

主机类声明：

unit uHostInterfaces;

interface

type
  IHost = interface
  ['{BAFA98BC-271A-4847-80CE-969377C03966}']
    procedure Start;
    procedure Stop;
  end;

  // this intf will get exposed to plugin
  IHostExposed = interface 
  ['{1C59B1A9-EC7A-4D33-A574-96DF8F5A7857}']
    function GetVar1: Integer;
    function GetVar2: String;

    procedure SetVar1(const AValue: Integer);
    procedure SetVar2(const AValue: String);

    property Var1: Integer read GetVar1 write SetVar1;
    property Var2: String read GetVar2 write SetVar2;
  end;

implementation

end.

unit uHost;

interface

uses
  Winapi.Windows, Winapi.Messages,
  uHostInterfaces, uInstanceController, uSettings;

type
  THost = class(TInterfacedObject, IHost, IHostExposed)
  private
    FVar1              : Integer;
    FVar2              : String;

    FWindowHandle      : HWND;
    FInstanceController: TInstanceController;
    FSettings          : TSettings;

    procedure WndProc(var AMessage: TMessage);

  public
    constructor Create;
    destructor Destroy; override;

    // methods from IHost
    procedure Start;
    procedure Stop;

    // methods from IHostExposed, which get set Var1/Var2
    function GetVar1: Integer;
    function GetVar2: string;

    procedure SetVar1(const AValue: Integer);
    procedure SetVar2(const AValue: string);
  end;

  implementation

  ...

type
  TRegisterPlugin = procedure(const AHostExposed: IHostExposed);

var
  hdll          : THandle;
  RegisterPlugin: TRegisterPlugin;
  host          : IHost;

begin
  host := THost.Create;

  hdll := LoadLibrary('plugin.dll');
  if hdll <> 0 then
  begin
    @RegisterPlugin := GetProcAddress(hdll, 'RegisterPlugin');
    if Assigned(RegisterPlugin) then
    begin
      // call the plugin function and pass IHostExposed interface to it
      // from there on, plugin can use this interface to interact with core app
      RegisterPlugin(host as IHostExposed); 

      ...

…我将如何使用它：

unit uHostInterfaces;

interface

type
  IHost = interface
  ['{BAFA98BC-271A-4847-80CE-969377C03966}']
    procedure Start;
    procedure Stop;
  end;

  // this intf will get exposed to plugin
  IHostExposed = interface 
  ['{1C59B1A9-EC7A-4D33-A574-96DF8F5A7857}']
    function GetVar1: Integer;
    function GetVar2: String;

    procedure SetVar1(const AValue: Integer);
    procedure SetVar2(const AValue: String);

    property Var1: Integer read GetVar1 write SetVar1;
    property Var2: String read GetVar2 write SetVar2;
  end;

implementation

end.

unit uHost;

interface

uses
  Winapi.Windows, Winapi.Messages,
  uHostInterfaces, uInstanceController, uSettings;

type
  THost = class(TInterfacedObject, IHost, IHostExposed)
  private
    FVar1              : Integer;
    FVar2              : String;

    FWindowHandle      : HWND;
    FInstanceController: TInstanceController;
    FSettings          : TSettings;

    procedure WndProc(var AMessage: TMessage);

  public
    constructor Create;
    destructor Destroy; override;

    // methods from IHost
    procedure Start;
    procedure Stop;

    // methods from IHostExposed, which get set Var1/Var2
    function GetVar1: Integer;
    function GetVar2: string;

    procedure SetVar1(const AValue: Integer);
    procedure SetVar2(const AValue: string);
  end;

  implementation

  ...

type
  TRegisterPlugin = procedure(const AHostExposed: IHostExposed);

var
  hdll          : THandle;
  RegisterPlugin: TRegisterPlugin;
  host          : IHost;

begin
  host := THost.Create;

  hdll := LoadLibrary('plugin.dll');
  if hdll <> 0 then
  begin
    @RegisterPlugin := GetProcAddress(hdll, 'RegisterPlugin');
    if Assigned(RegisterPlugin) then
    begin
      // call the plugin function and pass IHostExposed interface to it
      // from there on, plugin can use this interface to interact with core app
      RegisterPlugin(host as IHostExposed); 

      ...

类型
TRegisterPlugin=过程（const ahosexposed:ihoosexposed）；
变量
hdll:THandle；
RegisterPlugin:TRegisterPlugin；
主持人:IHost,；
开始
主机：=THost.Create；
hdll:=LoadLibrary（'plugin.dll'）；
如果hdll为0，则
开始
@RegisterPlugin:=GetProcAddress（hdll，'RegisterPlugin'）；
如果已分配（RegisterPlugin），则
开始
//调用插件函数并将IHostExposed接口传递给它
//从那个里开始，插件可以使用这个接口与核心应用程序进行交互
RegisterPlugin（如我所透露的主机）；
...

---

我想听到的是关于这种方法的任何建议，以及是否有更好的解决方案来实现我的目标？

显然您以前使用过接口，但您不知道COM的组件注册功能？使用“新建项目向导”启动包含自动化对象的ActiveX库，查看类型库编辑器，并查看库运行和注册时会发生什么（都在System.Win.ComServ.pas中）

显然您以前使用过接口，但不知道COM的组件注册功能？使用“新建项目向导”启动包含自动化对象的ActiveX库，查看类型库编辑器，并查看库运行和注册时会发生什么（都在System.Win.ComServ.pas中）

这实际上是我第一次使用接口。谢谢，我来看看ComServ.past这实际上是我第一次使用接口。谢谢，我将查看ComServ.pas