这个DEMO用来演示服务的替换，用起来总是怪怪的感觉，效果图如下
代码如下
unit Frm_Main; interface uses
Winapi.Windows,
Winapi.Messages,
System.SysUtils,
System.Variants,
System.Classes,
Vcl.Graphics,
Vcl.Controls,
Vcl.Forms,
Vcl.Dialogs,
Vcl.ExtCtrls,
Vcl.StdCtrls,
qplugins_base,
QPlugins; type
// 定义一个接口，方法由子类来实现
IEchoService = interface
['{E9A9E0D8-F278-46CC-9AA4-7FCD9CDAB77F}']
function Echo(S: string): string;
end; // Echo接口的实例
TEchoService = class(TQService, IEchoService)
function Echo(S: string): string;
end; TEchoReplacement = class(TInterfacedObject, IEchoService)
function Echo(S: string): string;
end; TForm_Main = class(TForm)
Button1: TButton;
Memo1: TMemo;
Panel1: TPanel;
Button2: TButton;
procedure Button1Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure Button2Click(Sender: TObject);
private
{ Private declarations }
FReplaced: IEchoService;
public
{ Public declarations }
end; var
Form_Main: TForm_Main; implementation {$R *.dfm} // 按钮_调用服务
procedure TForm_Main.Button1Click(Sender: TObject);
var
AService: IEchoService;
begin
// PluginsManager函数返回全局PluginsManager实例
AService := PluginsManager as IEchoService;
// 服务存在，则调用
if Assigned(AService) then
begin
Memo1.Lines.Add(AService.Echo('服务插件'));
end;
end; // 按钮_替换服务
procedure TForm_Main.Button2Click(Sender: TObject);
var
AService: IQService;
begin
// 在指定的父结点下，查找指定路径的服务
AService := FindService('/Services/Echo');
// 如果服务存在
if Assigned(AService) then
begin
// 撤销替换服务
if Assigned(FReplaced) then
begin
AService.RemoveExtension(FReplaced);
FReplaced := nil;
Button2.Caption := '替换服务';
end
else
begin
// 替换服务
FReplaced := TEchoReplacement.Create;
AService.AddExtension(FReplaced);
Button2.Caption := '撤销替换';
end;
end;
end;
{ TEchoService } // 原Echo函数
function TEchoService.Echo(S: string): string;
begin
Result := Format('类名[%s]: %s', [ClassName, S]);
end; { TEchoReplacement }
// 新Echo函数
function TEchoReplacement.Echo(S: string): string;
begin
Result := Format('新类名[%s]: %s', [ClassName, S]);
end; // 创建
procedure TForm_Main.FormCreate(Sender: TObject);
begin
// 注册TEchoService服务
RegisterServices('/Services', [TEchoService.Create(IEchoService, 'Echo')]);
end; end.