本例演示了一个消息的定义、发送和接受的过程.
本例效果图:
![](https://www.cnblogs.com/images/cnblogs_com/del/138617/o_86195.gif)
代码文件:
本例效果图:
![](https://www.cnblogs.com/images/cnblogs_com/del/138617/o_86195.gif)
代码文件:
unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TForm1 = class(TForm) Button1: TButton; procedure FormCreate(Sender: TObject); procedure Button1Click(Sender: TObject); private procedure AppMessage(var Msg: TMsg; var Handled: Boolean); end; var Form1: TForm1; implementation {$R *.dfm} const WM_MyMessage = WM_USER + 2000; procedure TForm1.FormCreate(Sender: TObject); begin Application.OnMessage := AppMessage; Button1.Caption := '发送自定义消息'; end; procedure TForm1.AppMessage(var Msg: TMsg; var Handled: Boolean); var msgStr: String; begin if Msg.hwnd = Application.Handle then begin if Msg.message = WM_MyMessage then begin msgStr:= PChar(Msg.lParam); ShowMessage(msgStr); Handled := True; end; end; end; procedure TForm1.Button1Click(Sender: TObject); const lParam: PChar = '来自定义消息'; begin PostMessage(Application.Handle, WM_MyMessage, 0, Integer(lParam)); end; end.窗体文件:
object Form1: TForm1 Left = 0 Top = 0 Caption = 'Form1' ClientHeight = 117 ClientWidth = 225 Color = clBtnFace Font.Charset = DEFAULT_CHARSET Font.Color = clWindowText Font.Height = -11 Font.Name = 'Tahoma' Font.Style = [] OldCreateOrder = False Position = poDesktopCenter OnCreate = FormCreate PixelsPerInch = 96 TextHeight = 13 object Button1: TButton Left = 48 Top = 48 Width = 129 Height = 25 Caption = 'Button1' TabOrder = 0 OnClick = Button1Click end end