Delphi中多线程用消息实现VCL数据同步显示

Delphi中多线程用消息实现VCL数据同步显示

Lanno Ckeeke 

2006-5-12

概述：

delphi中严格区分主线程和子主线程，主线程负责GUI的更新，子线程负责数据运算，当数据运行完毕后，子线程可以向主线程式发送消息，以便通知其将VCL中的数据更新。

实现：

关键在于消息的发送及接收。在消息结构Tmessage中wParam和lParam类型为Longint，而指针类型也定义为Longint，可以通过此指针来传递自己所感兴趣的数据。如传递字符数组：

数组定义：


              const 

MAX_LEN = 260;

              szName : array[0..MAX_LEN] of Char;
 

消息发送方式：

              PostMessage(Form1.Handle,WM_UPDATEDATA,Integer(PChar(@szName)),0);

消息接收方式：


              procedure TForm1.WMUpdateData(var msg : TMessage);

begin

       self.ShowData.Items.Add(PChar(msg.WParam));

end;
 

 

子线程中定义两个数据类型：


 public

     szName : array[0..MAX_LEN] of Char;

    nIndex : Integer;
 

 

完整代码：

子线程类：


unit TChildThread;

 

interface

 

uses

 Classes,Messages,Windows,SysUtils;//添加的使用文件

 

const MAX_LEN = 260;

type

 TChildThreads = class(TThread)

 private

    { Private declarations }

 protected

    procedure Execute; override;

 public

      szName : array[0..MAX_LEN] of Char;

    nIndex : Integer;

 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 TChildThread.UpdateCaption;

    begin

      Form1.Caption := ‘Updated in a thread‘;

    end; }

 

{ TChildThread }

 

procedure TChildThreads.Execute;

begin

 { Place thread code here }

   PostMessage(Form1.Handle,WM_UPDATEDATA,Integer(PChar(@szName)),0);

   //注意类型转化部分的写法

end;

 

end.
 

主线程代码：


unit Unit1;

 

interface

 

uses

 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

 Dialogs, StdCtrls, ComCtrls;

 

const

       WM_UPDATEDATA = WM_USER + 100;//自定义的消息，利用此消息来实现对GUI的更新

type

 TForm1 = class(TForm)

    ControlPannel: TGroupBox;

    StartThreads: TButton;

    TabControl1: TTabControl;

    SingleThread: TRadioButton;

    MultipleThreads: TRadioButton;

    StopThreads: TButton;

    ShowData: TListBox;

    ShowError: TListBox;

    Initialize: TButton;

Cleanup: TButton;

//GUI更新的消息处理函数声明

     procedure WMUpdateData(var msg : TMessage);message WM_UPDATEDATA;

    procedure StartThreadsClick(Sender: TObject);

 private

    { Private declarations }

 public

    { Public declarations }

 end;

 

var

 Form1: TForm1;

 

implementation

uses

       TChildThread;

 

{$R *.dfm}

//消息函数定义

procedure TForm1.WMUpdateData(var msg : TMessage);

begin

       self.ShowData.Items.Add(PChar(msg.WParam));

end;

 

procedure TForm1.StartThreadsClick(Sender: TObject);

var

       oChildThread : array[0..1000] of TChildThreads;

 i : Integer;

begin

       For i := 0 to 1000 do

 begin

     oChildThread[i] := TChildThreads.Create(true);

    //向VCL中发送的数据

    strcopy(@oChildThread[i].szName,PChar(‘Child‘ + IntToStr(i)));

    oChildThread[i].nIndex := i;

    oChildThread[i].Resume;

 end;

 

end;

 

end.