《GOF设计模式》—中介者 (MEDIATOR)—Delphi源码示例：Smalltalk/V的应用结构

示例：Smalltalk/V的应用结构
说明：
Windows下的Smalltalk/V的应用结构基于中介者结构。在这个环境中,一个应用由一个包含一组窗格(pane)的窗口组成。ViewManager类负责窗格间的协调工作。ViewManager是一个中介者，而每一个窗格只知道它的viewmanager,它被看作该窗格的"主人"。窗格不直接互相引用。Smalltalk/V的Pane-ViewManager通信使用一种事件机制。
下面的对象图显示了一个应用运行时刻的情景。
 


代码：
 


unit uPane;

interface

uses
    Classes,Dialogs, Contnrs;

type
    TViewManager = class;

    TPane = class
    private
        FOwner: TViewManager;
        FPaneName: string;
    public
        constructor Create(const APaneName: string;AOwner: TViewManager);
        //---
        property PaneName: string read FPaneName write FPaneName;
    end;
    TTextPane = class(TPane)
    private
        FOnChanged: TNotifyEvent;
        FText: string;
        procedure SetText(const Value: string);
    public
        property Text: string read FText write SetText;
        property OnChanged: TNotifyEvent read FOnChanged write FOnChanged;
    end;
    TListBox1 = class(TPane)
    private
        FOnChanged: TNotifyEvent;
    public
        procedure Add(s: string);
        //---
        property OnChanged: TNotifyEvent read FOnChanged write FOnChanged;
    end;
    TButton1 = class(TPane)
    private
        FOnClick: TNotifyEvent;
    public
        procedure Click;
        //---
        property OnClick: TNotifyEvent read FOnClick write FOnClick;
    end;
    TListPane = class(TPane)
    private
        FOnSelect: TNotifyEvent;
    public
        procedure Select;
        property OnSelect: TNotifyEvent read FOnSelect write FOnSelect;
    end;

    TViewManager = class
    private
        FPanes:TObjectList;
    public
        constructor Create;
        destructor Destroy; override;
        //---
        procedure AddSubPane(APane:TPane);
    end;
    TConcreteViewManager = class(TViewManager)
    private
        FTextPane: TTextPane;
        FListBox: TListBox1;
        FButton: TButton1;
        FListPane: TListPane;
        procedure ListSelect(Sender: TObject);
        procedure TextChanged(Sender: TObject);
        procedure ListBoxChanged(Sender: TObject);
        procedure ButtonClick(Sender: TObject);
    public
        constructor Create;
        //---
        procedure Test;
    end;

procedure Test;

implementation

procedure Test;
var
    AViewManager: TConcreteViewManager;
begin
    AViewManager := TConcreteViewManager.Create;
    AViewManager.Test;
    AViewManager.Free;
end;

procedure TTextPane.SetText(const Value: string);
begin
    FText := Value;
    if Assigned(FOnChanged) then
        FOnChanged(self);
end;

procedure TListBox1.Add(s: string);
begin
    if Assigned(FOnChanged) then
        FOnChanged(self);
end;

procedure TButton1.Click;
begin
    if Assigned(FOnClick) then
        FOnClick(self);
end;

{ TListPane }

procedure TListPane.Select;
begin
    if Assigned(FOnSelect) then
        FOnSelect(self);
end;

constructor TPane.Create(const APaneName: string;AOwner: TViewManager);
begin
    FOwner := AOwner;
    FPaneName := APaneName;
end;

procedure TConcreteViewManager.ButtonClick(Sender: TObject);
begin
    ShowMessage(FButton.PaneName);
end;

constructor TConcreteViewManager.Create;
begin
    inherited;
    //---
    FTextPane := TTextPane.Create('myTextPane',self);
    FTextPane.OnChanged := self.TextChanged;
    self.AddSubPane(FTextPane);
    //---
    FListBox := TListBox1.Create('myListBox',self);
    FListBox.OnChanged := self.ListBoxChanged;
    self.AddSubPane(FListBox);
    //---
    FButton := TButton1.Create('myButton',self);
    FButton.OnClick := self.ButtonClick;
    self.AddSubPane(FButton);
    //---
    FListPane := TListPane.Create('myListPane',self);
    FListPane.OnSelect := self.ListSelect;
    self.AddSubPane(FListPane);
end;

procedure TConcreteViewManager.ListBoxChanged(Sender: TObject);
begin
    ShowMessage(FListBox.PaneName);
end;

procedure TConcreteViewManager.ListSelect(Sender: TObject);
begin
    ShowMessage(FListPane.PaneName);
end;

procedure TViewManager.AddSubPane(APane: TPane);
begin
    FPanes.Add(APane);
end;

constructor TViewManager.Create;
begin
    FPanes := TObjectList.Create;
end;

destructor TViewManager.Destroy;
begin
    FPanes.Free;
    //---
    inherited;
end;

procedure TConcreteViewManager.Test;
begin
    FTextPane.Text := '123';
end;

procedure TConcreteViewManager.TextChanged(Sender: TObject);
begin
    ShowMessage(FTextPane.Text);
end;

end.