1 unit Unit1;
 2 
 3 interface
 4 
 5 uses
 6   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 7   Dialogs, StdCtrls, Buttons;
 8 
 9 type
10 TForm1 = class(TForm)
11     Button2: TButton;
12     Button3: TButton;
13     BitBtn1: TBitBtn;
14     procedure Button2Click(Sender: TObject);
15     procedure FormShow(Sender: TObject);
16     procedure BitBtn1Click(Sender: TObject);
17 private
18     { Private declarations }
19 
20     I: Integer;
21 
22 public
23     { Public declarations }
24 
25 end;
26 
27 var
28   Form1: TForm1;
29 
30 implementation
31 
32 
33 {$R *.dfm}
34 
35 { TForm1 }
36 procedure TForm1.FormShow(Sender: TObject);
37 begin
38   I:= RegisterWindowMessage('MyMessage');
39 end;
40 procedure TForm1.BitBtn1Click(Sender: TObject);
41 var
42   h1: HWND;
43 begin
44   h1:= FindWindow(nil,'Form2');
45   PostMessage(h1,I,0,1);
46 end;

 1 unit Unit1;
 2 
 3 interface
 4 
 5 uses
 6   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 7   Dialogs, StdCtrls, AppEvnts, Buttons,QExtCtrls, ExtCtrls;
 8 const
 9   My_MousL = WM_USER+100;
10 type
11 TForm2 = class(TForm)
12     Button1: TButton;
13     ApplicationEvents1: TApplicationEvents;
14     BitBtn1: TBitBtn;
15     BtnCreatePanel: TBitBtn;
16     BitBtn2: TBitBtn;
17     BitBtn3: TBitBtn;
18     Panel1: TPanel;
19     Button2: TButton;
20     procedure FormShow(Sender: TObject);
21 private
22     { Private declarations }
23     J: Integer;
24 public
25     { Public declarations }
26     procedure   WndProc(var   Message:   TMessage);   override;
27 end;
28 
29 var
30 Form2: TForm2;
31 
32 implementation
33 
34 {$R *.dfm}
35 
36 procedure TForm1.FormShow(Sender: TObject);
37 begin
38   J:= RegisterWindowMessage('MyMessage');
39 end;
40 
41 procedure TForm1.WndProc(var Message: TMessage);
42 begin
43   if Message.Msg = J then
44     ShowMessage('得到消息')
45   else
46     inherited;
47 end;

 1 private
 2   strWM:Cardinal;  //定义一个局部变量
 3   //...
 4 proccedure Form1.Create(sender:TObject);
 5 begin
 6   strWM:= RegisterWindowMessage('newspopMessage'); //注册一个windows全局消息,通过这个消息与其它进程通信
 7 end;
 8 
 9 10 procedure Form1.Button1Click1(Sender:TObject);
11 var
12   h:Cardinal;
13 begin
14   //通信的步骤得先找到要通信的信息窗口Handle
15   h:=findWindow('目标进程窗口类名','窗口Caption');
16   //发送消息消息类型为自定义的strWM
17   SendMessage(h,strWM,0,0);  //这里同样可以带参数：wParam,lParam。但我传一个PChar,读取的时候总报错，不知道为啥
18 end;

 1         private
 2             strWM:Cardinal;  //定义一个局部变量
 3             procedure wndProc(var msg:Tmessage);override; //覆盖这个方法,可以监听所有的Windows消息回调函数  
 4          ...   
 5         proccedure Form1.Create(sender:TObject);
 6         begin
 7             strWM:= RegisterWindowMessage('newspopMessage'); //注册一个windows全局消息,这个相当于暗号
 8         end;
 9         procecure form1.wndProc(var msg:TMessage);
10         begin
11             //在这里处理这个消息就行了
12             showmessage(strpas(PChar(msg.lparam))); //这样写会报错的.但可以处理其它无参数的事情
13         end;

 1 procedure TMainForm.CallAgent(msg: string);
 2   var
 3     HlAgent:HWND;
 4     ds:TCopyDatastruct;    //定义一个TCopyDatastruct结构体变量
 5   begin
 6     //AgentMsg := msg;
 7     ds.cbData := (Length(msg)+1)*SizeOf(char); //结构体的第一个元素: 长度cbData
 8     GetMem(ds.lpData,ds.cbData); //分配内存,结构体的第二个参数:  数据的指针lpDATA
 9     StrCopy(ds.lpData,PChar(msg)); //复制值到结构指针
10 
11     HlAgent :=FindWindow('TmsgpopMainCaller','调用者');  //查找目标窗体的Handle
12     if  HlAgent <> 0 then
13     begin
14       //ShowMessage('主' + IntToStr(Cardinal(@ds)));
15       SendMessage(HlAgent,WM_COPYDATA,0,Cardinal(@ds));   //发送WM_COPYDATA消息,并带上参数 @ds
16     end;
17     FreeMem(ds.lpData); //释放数据内存
18   end;

 1     public
 2             procedure MyMessage(var m:TWmCopyData);message WM_CopyData;   //定义一个消息响应过程,并传入一个TWmCopyData的参数
 3     ...
 4     procedure TmsgpopMainCaller.MyMessage(var m: TWmCopyData); //实现响应
 5     var
 6       msg:string;
 7     begin
 8       msg :=StrPas(m.CopyDataStruct^.lpData);    //获取参数数据
 9       ShowMessageForm := TShowMessageForm.Create(self,msg);  //处理
10     end;