两个程序间访问

Question

有两个程序，a,b。   
  单击a程序的一个button后，b程序根据a程序的操作立刻反应，然后进行某个操作。应该怎么办？
  这里的主要难点是如何让数据在两个程序间交换。
谢谢   

Answer 1

进程通讯(自定义消息)SenderMain.pas 
unit SenderMain;
interface
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
  Const WM_COMM = WM_APP+100;
  Const str='Receiver';
type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
  function ShowProcess(Whandle: HWND):boolean ;
var
  Form1: TForm1;
implementation
{$R *.dfm}
function ShowProcess(Whandle: HWND):boolean ;
begin
ShowWindow(Whandle,SW_restore);
SetForegroundWindow(Whandle);
SetActiveWindow(Whandle);
result :=true;
end;procedure TForm1.Button1Click(Sender: TObject);
var
whd : HWND;
begin
whd:=FindWindow(nil,pchar(str));
ShowProcess(whd);
SendMessage(whd,WM_COMM,0,0);
end;
procedure TForm1.Button2Click(Sender: TObject);
var
whd : HWND;
begin
whd:=FindWindow(nil,pchar(str));
ShowProcess(whd);
SendMessage(whd,WM_COMM,0,1);
end;
procedure TForm1.Button3Click(Sender: TObject);
var
whd : HWND;
begin
whd:=FindWindow(nil,pchar(str));
ShowProcess(whd);
SendMessage(whd,WM_COMM,1,0);
end;
end.
receivemain.pasunit receivemain;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
  Const WM_COMM = WM_APP+100;
type
  TForm1 = class(TForm)
    Edit1: TEdit;
  private
    { Private declarations }
    procedure userpro(var msg:TMessage); message WM_COMM;
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation//uses receivemain;{$R *.dfm}
procedure TForm1.userpro(var msg:TMessage); 
begin
if(msg.WParam=0)and(msg.LParam=0)then
Edit1.Text:='命令一 ';
if(msg.WParam=0)and(msg.LParam=1)then
Edit1.Text:='命令二 ';
if(msg.WParam=1)and(msg.LParam=0)then
Edit1.Text:='命令三 ';
end;end.

Answer 2

进程通信(自定义数据)
进程通信(自定义数据)
unit Unit1;
interface
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
Const WM_COMM = WM_APP+100;
type
  TForm1 = class(TForm)
    Button1: TButton;
    ListBox1: TListBox;
    Button2: TButton;
    Button3: TButton;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    procedure GetUsername(var msg:TWmCopyData); message WM_COPYDATA;
    procedure ReturnResult(var msg:TMessage); message WM_COMM;
  public
    { Public declarations }
  end;
  function EnumWndProc(AWnd:HWND;AlParam:LPARAM):Boolean;stdcall;
var
  Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
begin
  ListBox1.Clear;
  EnumWindows(@EnumWndProc,0);//枚举窗体,发送消息
end;
function EnumWndProc(AWnd:HWND;AlParam:LPARAM):Boolean;stdcall;
var
  WndCaption: array[0..254] of Char;
  ds: TCopyDataStruct;
begin
  GetWindowText(AWnd, @WndCaption, 254);
  if WndCaption[0]<>chr(0) then
    Form1.ListBox1.Items.Add(Format('%d=%s',[AWnd,StrPas(WndCaption)]));
  if WndCaption='彭轩' then
  begin
     ds.cbData := Length (Form1.Edit1.Text) + 1;
     GetMem (ds.lpData, ds.cbData ); //为传递的数据区分配内存
     StrCopy (ds.lpData, PChar (Form1.Edit1.Text));
     SendMessage(AWnd,WM_COPYDATA,Form1.Handle,Cardinal(@ds));
  end;
  Result := True;
end;
procedure TForm1.ReturnResult(var msg: TMessage);
begin
  if msg.WParam=1 then
     ShowMessage('返回');
end;
procedure TForm1.GetUsername(var msg: TWmCopyData);
begin
  //接收其它进程发来的消息,并判断消息来源不是自己本身
  //取出消息携带的数据与Edit1.Text比较
  if msg.From<>Form1.Handle then
  begin
    if Edit1.Text=StrPas(msg.CopyDataStruct^.lpData) then
       SendMessage(msg.From,WM_COMM,1,0);
  end;
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
  ListBox1.Clear;
  EnumWindows(@EnumWndProc,0);
end;
procedure TForm1.Button3Click(Sender: TObject);
begin
  Edit1.Text:='aaa';
end;
end.
 注意 EnumWindows(@EnumWndProc,0);//枚举窗体,发送消息
在枚举窗体时,会认为同一个程序的窗口和工程是两个窗体,比如一个工程中
Form1.Caption:='进程通信2';
Application.Title:='进程通信';
这里会找到两个窗体 "进程通信2"和"进程通信"