DELPHI 多线程（TThread类的实现）

Posted 2020-08-04

DELPHI 多线程（TThread类的实现）

先新建一个普通的工程，再新建一个线程类File>>New>>Othre>>Delphi File>Thread Object，取个名字，DELPHI会自动生成一个单元，我们只需往里简单添加功能代码，和在要使用的单元里实例引用即可。

为了节省篇幅，现把TMyThread类集成主窗体单元里，在主窗体里声明类也是可以的。

 1 unit Unit1;
 2 
 3 interface
 4 
 5 uses
 6   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 7   Dialogs, StdCtrls;
 8 
 9 type
10   TMyThread = class(TThread)
11   private
12     { Private declarations }
13   protected
14     procedure Execute; override;
15     procedure Run;
16   end;
17   TForm1 = class(TForm)
18     btn1: TButton;
19     procedure btn1Click(Sender: TObject);
20   private
21     { Private declarations }
22   public
23     { Public declarations }
24   end;
25 
26 
27 
28 var
29   Form1: TForm1;
30 
31 
32 implementation
33 
34 {$R *.dfm}
35 
36 var
37   MyThread:TMyThread;
38 
39 procedure TMyThread.Execute;
40 begin
41   { Place thread code here }
42   FreeOnTerminate:=True; {加上这句线程用完了会自动注释}
43   Run;
44 end;
45 
46 procedure TMyThread.Run;
47 var
48   i:integer;
49 begin
50   for i := 0 to 500000 do
51   begin
52     Form1.Canvas.Lock;
53     Form1.Canvas.TextOut(10,10,IntToStr(i));
54     Form1.Canvas.Unlock;
55   end;
56 end;
57 
58 procedure TForm1.btn1Click(Sender: TObject);
59 begin
60   MyThread:=TMyThread.Create(False); {实例化这个类，为False时立即运行，为True时可加MyThread.Resume用来启动}
61 end;

CriticalSection(临界区)

 uses SyncObjs;用TCriticalSection类的方法处理。

 1 unit Unit1;
 2 
 3 interface
 4 
 5 uses
 6   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 7   Dialogs, StdCtrls;
 8 
 9 type
10   TMyThread = class(TThread)
11   private
12     { Private declarations }
13   protected
14     procedure Execute; override; {执行}
15     procedure Run;  {运行}
16   end;
17   TForm1 = class(TForm)
18     btn1: TButton;
19     lst1: TListBox;
20     procedure btn1Click(Sender: TObject);
21     procedure FormDestroy(Sender: TObject);
22   private
23     { Private declarations }
24   public
25     { Public declarations }
26   end;
27 
28 
29 
30 var
31   Form1: TForm1;
32 
33 
34 implementation
35 
36 {$R *.dfm}
37 
38 uses SyncObjs;
39 
40 var
41   MyThread:TMyThread;   {声明线程}
42   CS:TCriticalSection; {声明临界体}
43 
44 
45 procedure TMyThread.Execute;
46 begin
47   { Place thread code here }
48   FreeOnTerminate:=True; {加上这句线程用完了会自动注释}
49   Run;     {运行}
50 end;
51 
52 procedure TMyThread.Run;
53 var
54   i:integer;
55 begin
56   CS.Enter;  {我要用了，其它人等下}
57   for i := 0 to 100 - 1 do
58   begin
59     Form1.lst1.Items.Add(IntToStr(i));
60   end;
61   CS.Leave;  {我用完了，下一个}
62 end;
63 
64 procedure TForm1.btn1Click(Sender: TObject);
65 begin
66   CS:=TCriticalSection.Create;     {实例化临界体}
67   MyThread:=TMyThread.Create(False); {实例化这个类，为False时立即运行，为True时可加MyThread.Resume用来启动}
68   MyThread:=TMyThread.Create(False);
69   MyThread:=TMyThread.Create(False);
70 end;
71 
72 
73 procedure TForm1.FormDestroy(Sender: TObject);
74 begin
75   CS.Free;{释放临界体}
76 end;
77 
78 end.

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等待函数 PS：
function WaitForSingleObject(
hHandle: THandle; {要等待的对象句柄}
dwMilliseconds: DWORD {等待的时间, 单位是毫秒}
): DWORD; stdcall; {返回值如下:}

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.

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