Delphi使用TStringHash实现建立类（有点像反射）

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, jpeg, ExtCtrls,
  IniFiles;//TStringHash使用

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Image1: TImage;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

type
  // 边信息基类接口
  IClassInfo = interface
  ['{219E2CE1-78AE-4479-A4D8-A23DB421621C}']
    function GetName: string;
  end;
  //
  TInfoClass = class of TMyClass;
  //自定义的类
  TMyClass = class(TObject, IInterface)
  protected
    FRefCount: Integer;
  private
    FMyName: string;
  public
    function QueryInterface(const IID: TGUID; out Obj): HResult; stdcall;
    function _AddRef: Integer; stdcall;
    function _Release: Integer; stdcall;
    constructor Create; virtual;
    function GetName: string; virtual;
    property  RefCount: Integer read FRefCount;
  end;
  //展示类
  TMyClass1 = class(TMyClass, IClassInfo)
  private
    FMyName: string;
  public
    constructor Create; override;
    function GetName: string; override;
  end;
  //工厂类
  TClassInfoFactroy = class
    class function CreateClass(const ATypeID: Integer): TMyClass;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

var
  MyClassList: TStringHash;

{ TMyClass }
//注册类方法
procedure RegisterMyClass(const ATypeID: Integer; AClass: TInfoClass);
var
  num: Integer;
begin
   num := MyClassList.ValueOf(IntToStr(ATypeID));
   if num = -1  then
     MyClassList.Add(IntToStr(ATypeID), Integer(AClass))
   else
    Assert(False, Format('ElementTypeID %d ''s EdgeInfo already registered', [ATypeID]));
end;

constructor TMyClass.Create;
begin
// 子类实现
end;

function TMyClass.GetName: string;
begin
// 子类实现
end;

function TMyClass.QueryInterface(const IID: TGUID; out Obj): HResult;
begin
  if GetInterface(IID, Obj) then
    Result := 0
  else Result := E_NOINTERFACE;
end;

function TMyClass._AddRef: Integer;
begin
  Result := InterlockedIncrement(FRefCount);
end;

function TMyClass._Release: Integer;
begin
  Result := InterlockedDecrement(FRefCount);
  if Result = 0 then Destroy;
end;

{ TMyClass1 }

constructor TMyClass1.Create;
begin
  FMyName := '类1';
end;

function TMyClass1.GetName: string;
begin
  Result := FMyName;
end;

{ TClassInfoFactroy }
//建立类方法
class function TClassInfoFactroy.CreateClass(const ATypeID: Integer): TMyClass;
var
  nClass: Integer;
begin
  nClass := MyClassList.ValueOf(IntToStr(ATypeID)); 
  if nClass <> -1 then
    Result := TInfoClass(nClass).Create
  else begin
    Result := nil;
  end;
end;
//调用类方法
procedure TForm1.Button1Click(Sender: TObject);
begin
  Edit1.Text := (TClassInfoFactroy.CreateClass(123) as IClassInfo).GetName;
end;
//初始化
initialization
  if MyClassList = nil then
    MyClassList:= TStringHash.Create(26);
  // 注册类
  RegisterMyClass(123, TMyClass1);

end.