利用自定义事件实现不同窗体间的通讯 -- Delphi篇

要实现子窗体与父窗体之间的通讯，有多种方法（比如：重载子窗体的构造函数，将父窗体的引用作为参数传递给子窗体）。下面我要介绍的是利用自定义事件的方法，它能够最大程度的避免模块之间的耦合，充分体现面向对象的优点。

下面是实现代码：

Unit2 //子窗体

type

//声明自定义事件的类型（类似于C#中的委托）

TMyEventHandle = procedure (Sender: TObject; Content: string) of object;

TForm2 = class(TForm)

ComboBox1: TComboBox;

Label1: TLabel;

procedure ComboBox1Click(Sender: TObject);

private

FOnSelectionChanged: TMyEventHandle;

public

//声明自定义事件

property OnSelectionChanged: TMyEventHandle

read FOnSelectionChanged write FOnSelectionChanged;

end;

procedure TForm2.ComboBox1Click(Sender: TObject);

begin

//当选择改变时，触发自定义的事件

if Assigned(FOnSelectionChanged) then

FOnSelectionChanged(Self, ComboBox1.Text);

end;

Unit1 //父窗体

type

TForm1 = class(TForm)

btnOpenForm2: TButton;

Edit1: TEdit;

Label1: TLabel;

procedure btnOpenForm2Click(Sender: TObject);

private

m_frm2: TForm2;

procedure frm2_SelectionChanged(Sender: TObject; Content: string);

public

constructor Create(AOwner: TComponent); override;

destructor Destroy; override;

end;

constructor TForm1.Create(AOwner: TComponent);

begin

inherited Create(AOwner);

m_frm2 := TForm2.Create(Self);

//指定当m_frm2的自定义事件发生时的处理程序

m_frm2.OnSelectionChanged := frm2_SelectionChanged;

end;

destructor TForm1.Destroy;

begin

m_frm2.Free;

inherited Destroy;

end;

procedure TForm1.frm2_SelectionChanged(Sender: TObject; Content: string);

begin

Edit1.Text := Content;

end;

procedure TForm1.btnOpenForm2Click(Sender: TObject);

begin

m_frm2.ShowModal;

end;