能否直接调用另一个线程中的函数(100分)

张远

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在多线程应用程序中,在一个线程内,能否直接调用另一个线程中的函数?
 
为什麽没有人回答?
 
只要你有访问权限
 
可以,不过要注意数据的同步,最好问题能详细点
 
你应该指的是使用TThread创建的线程吧,如果是的话,就称为实例A,实例B。
在实例A所实现的线程可以直接调用实例B中的函数,
但实例B中的函数实际是在实例A所在线程执行的。
type
TB=class(TThread)
public
procedure qwe;
end;
...
var
b:TB;
...
procedure TA.Execute;
begin
TB.qwe;//实际TB.qwe是在本线程执行的。
end;
 
使用同步函数就可以拉
 
可以,假如B调用A的话,那么A必须先实例化,如果访问同一个外部变量的话,
要注意同步。
 
delphi做的多线程程序很慢,用vcl还要同步。
 
type
TThreadA = class(TThread)
public
class procedure ProcA;
end;

TThreadB = class(TThread)
public
procedure Execute;
override;
end;

用Class说明的公有函数可以在类没有实例化的情况下让其它类调用。
 
直接就可以调用啊。
 
线程类里的可访问函数(public)函数访问当然没有问题了,不过线程执行体不能访问哈
 
一直搞不清这个问题到底想问什么
好象kyq的答案比较接近一点?
不过为什么“实例B中的函数实际是在实例A所在线程执行的”?
 
访问其他线程中的函数是没有问题的(只要是公有函数)
varphone@263.net
 
你的概念有问题吧,线程是一个动态的概念。函数是静态的,实现一定功能的代码而已。
 
其实没有用线程A调B函数的必要
 

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, Unit2,ExtCtrls, Menus;
type
TForm1 = class(TForm)
GroupBox1: TGroupBox;
Button1: TButton;
Button2: TButton;
Button3: TButton;
Button4: TButton;
Panel1: TPanel;
Label1: TLabel;
Panel2: TPanel;
Label2: TLabel;
MainMenu1: TMainMenu;
File1: TMenuItem;
New1: TMenuItem;
Open1: TMenuItem;
Save1: TMenuItem;
Saveas1: TMenuItem;
N1: TMenuItem;
Exit1: TMenuItem;
Edit1: TMenuItem;
Cut1: TMenuItem;
GroupBox2: TGroupBox;
Button6: TButton;
Button7: TButton;
Button5: TButton;
Panel3: TPanel;
Label3: TLabel;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
procedure Button4Click(Sender: TObject);
procedure Button5Click(Sender: TObject);
procedure Exit1Click(Sender: TObject);
procedure Button6Click(Sender: TObject);
procedure Button7Click(Sender: TObject);
private
{ Private declarations }
procedure Thread1Done(sende:Tobject);
procedure Thread2Done(sende:Tobject);
public
{ Public declarations }
Flabel2,Fabel2:Tlabel;
Thread1,Thread2:TMyThread;
function MyThreadFunc(P:pointer):Longint;stdcall;
end;

var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
begin
Button1.Enabled :=false;
Button2.Enabled :=true;
Thread1:=TMyThread.Create (form1.Label1,10000);
Thread1.OnTerminate:=thread1Done;
end;

procedure TForm1.Thread1Done(sende:Tobject);
begin
Button1.Enabled :=true;
Button2.Enabled :=false;
end;

procedure TForm1.Thread2Done(sende:Tobject);
begin
Button3.Enabled :=true;
Button4.Enabled :=false;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
Thread1.Terminate;
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
Button3.Enabled :=false;
Button4.Enabled :=true;
Thread2:=TMyThread.Create (form1.Label2,10000);
Thread2.OnTerminate:=thread2Done;
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
Thread2.Terminate ;
end;

procedure TForm1.Button5Click(Sender: TObject);
begin
close;
end;

procedure TForm1.Exit1Click(Sender: TObject);
begin
close;
end;

// ××××××××××××××实例二 ××××××××××××
//这是线程函数,它可以放在下面程序的任何地方
function TForm1.MyThreadFunc(P:pointer):Longint;stdcall;
var
i:integer;
DC:HDC;
S:string;
begin
DC:=GetDC(Panel3.Handle);
for i:=0 to 100000do
begin
S:=Inttostr(i);
Textout(DC,10,10,Pchar(S),length(S));
end;
ReleaseDC(Panel3.Handle,DC);
end;

procedure TForm1.Button6Click(Sender: TObject);
var
i:integer;
DC:HDC;
S:string;
begin
DC:=GetDC(Panel3.Handle);
for i:=0 to 100000do
begin
S:=Inttostr(i);
Textout(DC,10,10,Pchar(S),length(S));
end;
ReleaseDC(Panel3.Handle,DC);
end;

procedure TForm1.Button7Click(Sender: TObject);
begin
MyThreadfunc(nil);
//没有创建线程时,直接调用线程函数
end;

end.

unit Unit2;
interface
uses
Classes,stdctrls,SysUtils;
type
TMyThread = class(TThread)
private
{ Private declarations }
Flabel:Tlabel;
{传递当前操作的labeld名字}
Max:integer;
{传递要显示的最大数}
Fidx:integer;
{当前要显示的数}
Procedure updatelabel;
protected
procedure Execute;
override;
public
constructor create(Mylabel:Tlabel;number:integer);
{线程构造函数}
end;

implementation
uses unit1;
{ Important: Methods and properties of objects in VCL or CLX can only be used
in a method called using Synchronize, for example,
Synchronize(UpdateCaption);
and UpdateCaption could look like,
procedure TMyThread.UpdateCaption;
begin
Form1.Caption := 'Updated in a thread';
end;
}
{ TMyThread }

constructor TMyThread.create(Mylabel:Tlabel;number:integer);
{线程构造函数}
begin
inherited Create(false);
if number>1000000
then
number:=1000000;
if number<1
then
number:=1;
Max:=number;
Flabel:=mylabel;
FreeOnTerminate:=true;
end;

procedure TMyThread.Execute;
var idx:Integer;
begin
{ Place thread code here }
for idx:=0 to maxdo
begin
synchronize (updatelabel);
{注意此处}
fidx:=idx;
if terminated
then
exit;
end;
end;

Procedure TMyThread.updatelabel;
begin
flabel.caption:=inttostr(Fidx);
end;
end.
 
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