mutexfrm.pas

《Delphi 7经典问题解析》源代码 第一到七章 基础篇源程序 应用篇源程序

unit MutexFrm;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  //定义一个线程类
  TsyncThread = class(TThread)
  protected
    procedure execute; override;
  end;

  TfrmMutex = class(TForm)
    ListBox1: TListBox;
    btnExecute: TButton;
    ListBox2: TListBox;
    Label1: TLabel;
    Label2: TLabel;
    procedure btnExecuteClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    //定义线程实例变量
    Thread1, Thread2: TSyncThread;
    //自定义过程，在线程结束时调用
    procedure Thread1Done(sender: TObject);
    procedure Thread2Done(sender: TObject);
    { Private declarations }
  public
    { Public declarations }
  end;
const
  MaxSize = 100;
var
  frmMutex: TfrmMutex;
  //数据全局区
  GlobalData: array[1..MaxSize] of integer;
  IncNum: Integer = 0;
  //定义互斥对象句柄
  HMutex: THandle = 0;
implementation

{$R *.dfm}

//线程执行主体

procedure TSyncThread.execute;
var
  i: integer;
  WaitReturn: DWORD;
begin
  FreeOnTerminate := True;
  //进入同步，防止其他线程访问
  WaitReturn := WaitForSingleObject(HMutex, INFINITE);
  if WaitReturn = Wait_Object_0 then
    for i := 1 to Maxsize do
    begin
      Inc(IncNum);
      GlobalData[i] := IncNum;
      Sleep(10);
    end;
end;

//在窗体创建时，创建互斥量
procedure TfrmMutex.FormCreate(Sender: TObject);
begin
  HMutex := CreateMutex(nil, false, nil);
end;

//在窗体释放时，释放互斥量
procedure TfrmMutex.FormDestroy(Sender: TObject);
begin
  CloseHandle(HMutex);
end;

//创建线程实例

procedure TfrmMutex.btnExecuteClick(Sender: TObject);
begin
  Thread1 := TSyncThread.Create(false);
  Thread1.OnTerminate := Thread1Done;
  Thread2 := TSyncThread.Create(false);
  Thread2.OnTerminate := Thread2Done;
end;

//当线程1执行完后，将GlobalData数据显示出来

procedure TfrmMutex.Thread1Done(sender: TObject);
var
  i: integer;
begin
  ListBox1.Items.Clear;
  for i := 1 to MaxSize do
    Listbox1.Items.Add(intToStr(GlobalData[i]));
  //解除互斥，让其他线程可以访问
  ReleaseMutex(HMutex);
end;

//当线程2执行完后，将GlobalData数据显示出来

procedure TfrmMutex.Thread2Done(sender: TObject);
var
  i: integer;
begin
  ListBox2.Items.Clear;
  for i := 1 to MaxSize do
    Listbox2.Items.Add(intToStr(GlobalData[i]));
  //解除互斥，让其他线程可以访问
  ReleaseMutex(HMutex);
end;


end.