delphi处理消息的几种方式

2024-08-21 00:44:59

第一种：自定义处理单条消息

unit Unit2;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs;
type
TForm2 = class(TForm)
procedure FormCreate(Sender: TObject);
procedure FormCloseQuery(Sender: TObject; var CanClose: Boolean);
private
{ Private declarations }
//直接用 TWMQueryEndSession
procedure EndMsg(var nMsg: TWMQueryEndSession); Message WM_QUERYENDSESSION;
//也可以用这种
//procedure EndMsg(var nMsg: TMessage); Message WM_QUERYENDSESSION;
public
{ Public declarations }
end;
var
Form2: TForm2;
implementation
{$R *.dfm}
//收到WM_QUERYENDSESSION消息后就会触发这个过程
procedure TForm2.EndMsg(var nMsg: TWMQueryEndSession);
begin
//0 可以取消关机操作
nMsg.Result := 1;
ShowMessage('注销、重启、关机');
end;
end.

第二种：利用Application.OnMessage处理消息

unit Unit2;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs;
type
TForm2 = class(TForm)
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
procedure OnMsg(var nMsg: tagMSG; var nHandled: Boolean);
end;
var
Form2: TForm2;
implementation
{$R *.dfm}
//消息处理过程
procedure TForm2.OnMsg(var nMsg: tagMSG; var nHandled: Boolean);
begin
//处理……
//这里会收到各种消息……经测试无法收到WM_QUERYENDSESSION消息
end;
procedure TForm2.FormCreate(Sender: TObject);
begin
Application.OnMessage := OnMsg;
end;
end.

第三种：自己处理窗口函数，个人感觉这是最强大的，可以拦截一切发往窗口的消息！

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