Delphi多线程编程(9)--认识等待函数WaitForSingleObject

转载自：万一的博客

　　一下子跳到等待函数 WaitForSingleObject，是因为下面的Mutex、Semaphore、Event、WaitableTimer等同步手段都要使用这个函数。不过等待函数可不止WaitForSingleObject这一个，但是它是最简单的

function WaitForSingleObject(
    hHandle: THandle;    //要等待的对象句柄
    dwMillseconds: DWORD;    //等待的时间，单位是毫秒
): DWORD; srdcall;

　　返回值说明如下

WAIT_OBJECT_0      {等着了，本例中是：等的那个进程终于结束了}
WAIT_TIMEOUT       {等过了点（你指定的时间），也没等着}
WAIT_ABANDONED  {好不容易等着了，但是人家还是不让咱执行；这一般是互斥对象}

　　//WaitForSingleObject 的第二个参数一般给常数值 INFINITE, 表示一直等下去, 死等.

　　代码如下

unit Unit1;

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

type
    TForm1=class(TForm)
        Button1: TButton;
        procedure Button1Click(Sender: TObject);
    end;

var
    Form1: TForm1;

implementation
{$R *.dfm}

var
    hProcess: Thandle;    {进程句柄}

{等待一个指定句柄的进程什么时候结束}
function MyThreadFun(p: Pointer);DWORD;stdcall;
begin
    if WaitForSingleObject(hProcess, INFINITE)=WAIT_OBJECT_0 then
        Form1.Text:= Format(‘进程 %d 已关闭‘，[hProcess]);
    Result:= 0;
end;

procedure TForm1.Button1Click(Sender: Tobject);
var
    pInfo: TProcessInformation;
    sInfo: TStartupInfo;
    Path: Array[0..MAX_PATH-1] of Char;
    ThreadID: DWORD;
begin
    {先获得记事本的路径}
    GetSystemDirectory(Path, MAX_PATH);
    StrCat(Path, ‘\notepad.exe‘);

    {用 CreateProcess 打开记事本并获取进程句柄，然后建立线程监视}
    FillChar(sInfo, SizeOf(sInfo),0);
    if CreateProcess(Path, nil, nil, nil, False, 0, nil, nil, sInfo, pInfo) then
    begin
        hProcess:= pInfo.hProcess;    //获取进程句柄
        Text:= Format(‘进程 %d 已启动‘, [hProcess]);
        CreateThread(nil, 0, @MyThreadFun, nil, 0, ThreadID);    //建立线程监视
    end;
end;

end.

　　窗体文件

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = ‘Form1‘
  ClientHeight = 124
  ClientWidth = 241
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = ‘Tahoma‘
  Font.Style = []
  OldCreateOrder = False
  PixelsPerInch = 96
  TextHeight = 13
  object Button1: TButton
    Left = 88
    Top = 56
    Width = 75
    Height = 25
    Caption = ‘Button1‘
    TabOrder = 0
    OnClick = Button1Click
  end
end