本文提供的实例程序使用简单方便。利用一条串行数据线连接在两台计算机Com2之间就可以进行文本文件传输。对于Delphi的具体编程方法这里不再赘述。实例中有详细注释。
unit comunate;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
Dialogs, Buttons, StdCtrls, ComCtrls;
const
WM_COMMNOTIFY = WM_USER + 1; // 通讯消息
type
TForm1 = class(TForm)
Button1: TButton;
Button2: TButton;
Button3: TButton;
Button4: TButton;
OpenDialog1: TOpenDialog;
Label1: TLabel;
BitBtn1: TBitBtn;
RichEdit1: TRichEdit;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
procedure Button4Click(Sender: TObject);
private
{ Private declarations }
procedure WMCOMMNOTIFY(var Message :TMessage);message WM_COMMNOTIFY;
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
var
hNewCommFile,Post_Event: THandle;
Read_os : Toverlapped;
Receive :Boolean;
ReceiveData : Dword;
procedure AddToMemo(Str
Char;Len
word); // 接收的数据送入显示区
begin
str[Len]:=#0;
Form1.RichEdit1.Text:=Form1.RichEdit1.Text+StrPas(str);
end;
procedure CommWatch(Ptr
ointer);stdcall; // 通讯监视线程
var
dwEvtMask,dwTranser : Dword;
Ok : Boolean;
Os : Toverlapped;
begin
Receive :=True;
FillChar(Os,SizeOf(Os),0);
Os.hEvent :=CreateEvent(nil,True,False,nil); // 创建重叠读事件对象
if Os.hEvent=null then
begin
MessageBox(0,'Os.Event Create Error !','Notice',MB_OK);
Exit;
end;
if (not SetCommMask(hNewCommFile,EV_RXCHAR)) then
begin
MessageBox(0,'SetCommMask Error !','Notice',MB_OK);
Exit;
end;
while(Receive) do
begin
dwEvtMask:=0;
// 等待通讯事件发生
if not WaitCommEvent(hNewCommFile,dwEvtMask,@Os) then
begin
if ERROR_IO_PENDING=GetLastError then
GetOverLappedResult(hNewCommFile,Os,dwTranser,True)
end;
if ((dwEvtMask and EV_RXCHAR)=EV_RXCHAR) then
begin
// 等待允许传递WM_COMMNOTIFY通讯消息
WaitForSingleObject(Post_event,INFINITE);
// 处理WM_COMMNOTIFY消息时不再发送WM_COMMNOTIFY消息
ResetEvent(Post_Event);
// 传递WM_COMMNOTIFY通讯消息
Ok:=PostMessage(Form1.Handle,WM_COMMNOTIFY,hNewCommFile,0);
if (not Ok) then
begin
MessageBox(0,'PostMessage Error !','Notice',MB_OK);
Exit;
end;
end;
end;
CloseHandle(Os.hEvent); // 关闭重叠读事件对象
end;
procedure TForm1.WMCOMMNOTIFY(var Message :TMessage); // 消息处理函数
var
CommState : ComStat;
dwNumberOfBytesRead : Dword;
ErrorFlag : Dword;
InputBuffer : Array [0..1024] of Char;
begin
if not ClearCommError(hNewCommFile,ErrorFlag,@CommState) then
begin
MessageBox(0,'ClearCommError !','Notice',MB_OK);
PurgeComm(hNewCommFile,Purge_Rxabort or Purge_Rxclear);
Exit;
end;
if (CommState.cbInQue>0) then
begin
fillchar(InputBuffer,CommState.cbInQue,#0);
// 接收通讯数据
if (not ReadFile( hNewCommFile,InputBuffer,CommState.cbInQue,
dwNumberOfBytesRead,@Read_os )) then
begin
ErrorFlag := GetLastError();
if (ErrorFlag <> 0) and (ErrorFlag <> ERROR_IO_PENDING) then
begin
MessageBox(0,'ReadFile Error!','Notice',MB_OK);
Receive :=False;
CloseHandle(Read_Os.hEvent);
CloseHandle(Post_Event);
CloseHandle(hNewCommFile);
Exit;
end
else
begin
WaitForSingleObject(hNewCommFile,INFINITE); // 等待操作完成
GetOverlappedResult(hNewCommFile,Read_os,
dwNumberOfBytesRead,False);
end;
end;
if dwNumberOfBytesRead>0 then
begin
Read_Os.Offset :=Read_Os.Offset+dwNumberOfBytesRead;
ReceiveData := Read_Os.Offset;
// 处理接收的数据
AddToMemo(InputBuffer,dwNumberOfBytesRead);
end;
end;
// 允许发送下一个WM_COMMNOTIFY消息
SetEvent(Post_Event);
end;
procedure TForm1.Button1Click(Sender: TObject); // 打开文件用于发送
begin
if OpenDialog1.Execute then
begin
Button3.Enabled :=False;
Button4.Enabled :=False;
RichEdit1.Lines.LoadFromFile(OpenDialog1.FileName);
Form1.Caption := IntToStr(RichEdit1.GetTextLen);
end;
Button1.Enabled :=False;
end;
procedure TForm1.Button2Click(Sender: TObject); // 发送数据
var
dcb : TDCB;
Error :Boolean;
dwNumberOfBytesWritten,dwNumberOfBytesToWrite,
ErrorFlag,dwWhereToStartWriting : DWORD;
pDataToWrite : PChar;
write_os: Toverlapped;
begin
Form1.Caption :='';
// 打开通讯端口COM2
hNewCommFile:=CreateFile( 'COM2',GENERIC_WRITE,0,
nil, OPEN_EXISTING,FILE_FLAG_OVERLAPPED,0 );
if hNewCommFile = INVALID_HANDLE_VALUE then
MessageBox(0,'Error opening com port!','Notice',MB_OK);
SetupComm(hNewCommFile,1024,1024); // 设置缓冲区大小及主要通讯参数
GetCommState( hNewCommFile,dcb);
dcb.BaudRate :=9600;
dcb.ByteSize :=8;
dcb.Parity :=NOPARITY;
dcb.StopBits := ONESTOPBIT;
Error := SetCommState( hNewCommFile, dcb );
if ( not Error) then MessageBox(0,'SetCommState Error!','Notice',MB_OK);
dwWhereToStartWriting := 0;
dwNumberOfBytesWritten := 0;
dwNumberOfBytesToWrite :=RichEdit1.GetTextLen;
if (dwNumberOfBytesToWrite=0) then
begin
ShowMessage('Text Buffer is Empty!');
Exit;
end
else
begin
pDataToWrite:=StrAlloc(dwNumberOfBytesToWrite+1);
try
RichEdit1.GetTextBuf(pDataToWrite,dwNumberOfBytesToWrite);
Label1.Font.Color :=clRed;
FillChar(Write_Os,SizeOf(write_os),0);
// 为重叠写创建事件对象
Write_Os.hEvent := CreateEvent(nil,True,False,nil);
SetCommMask(hNewCommFile,EV_TXEMPTY);
Label1.Caption:='正在发送数据...!';
repeat
Label1.Repaint;
// 发送通讯数据
if not WriteFile( hNewCommFile,pDataToWrite[dwWhereToStartWriting],
dwNumberOfBytesToWrite,dwNumberOfBytesWritten,
@write_os ) then
begin
ErrorFlag :=GetLastError;
if ErrorFlag<>0 then
begin
if ErrorFlag=ERROR_IO_PENDING then
begin
WaitForSingleObject(Write_Os.hEvent,INFINITE);
GetOverlappedResult(hNewCommFile,Write_os,
dwNumberOfBytesWritten,False);
end
else
begin
MessageBox(0,'WriteFile Error!','Notice',MB_OK);
Receive :=False;
CloseHandle(Read_Os.hEvent);
CloseHandle(Post_Event);
CloseHandle(hNewCommFile);
Exit;
end;
end;
end;
Dec( dwNumberOfBytesToWrite, dwNumberOfBytesWritten );
Inc( dwWhereToStartWriting, dwNumberOfBytesWritten );
until (dwNumberOfBytesToWrite <= 0); // Write the whole thing!
Form1.Caption:=IntToStr(dwWhereToStartWriting);
finally
StrDispose(pDataToWrite);
end;
CloseHandle(hNewCommFile);
end;
Label1.Font.Color :=clBlack;
Label1.Caption:='发送成功!';
Button1.Enabled :=True;
Button3.Enabled :=True;
Button4.Enabled :=True;
end;
procedure TForm1.Button3Click(Sender: TObject); // 接收处理
var
Ok : Boolean;
dcb : TDCB;
com_thread: Thandle;
ThreadID
WORD;
begin
ReceiveData :=0;
Button1.Enabled :=False;
Button2.Enabled :=False;
RichEdit1.Clear;
// 打开COM2
hNewCommFile:=CreateFile( 'COM2'，GENERIC_READ,0,
nil, OPEN_EXISTING,FILE_FLAG_OVERLAPPED,0 );
if hNewCommFile = INVALID_HANDLE_VALUE then
begin
MessageBox(0,'Error opening com port!','Notice',MB_OK);
Exit;
end;
Ok:=SetCommMask(hNewCommFile,EV_RXCHAR);
if ( not Ok) then
begin
MessageBox(0,'SetCommMask Error!','Notice',MB_OK);
Exit;
end;
SetupComm(hNewCommFile,1024,1024);
GetCommState( hNewCommFile, dcb );
dcb.BaudRate :=9600;
dcb.ByteSize :=8;
dcb.Parity :=NOPARITY;
dcb.StopBits := ONESTOPBIT;
Ok := SetCommState( hNewCommFile, dcb );
if ( not Ok) then MessageBox(0,'SetCommState Error!','Notice',MB_OK);
FillChar(Read_Os,SizeOf(Read_Os),0);
Read_Os.Offset := 0;
Read_Os.OffsetHigh := 0;
// Create Event for Overlapped Read
Read_Os.hEvent :=CreateEvent(nil,true,False,nil);
if Read_Os.hEvent=null then
begin
CloseHandle(hNewCommFile);
MessageBox(0,'CreateEvent Error!','Notice',MB_OK);
Exit;
end;
// Create Event for PostMessage
Post_Event:=CreateEvent(nil,True,True,nil);
if Post_Event=null then
begin
CloseHandle(hNewCommFile);
CloseHandle(Read_Os.hEvent);
MessageBox(0,'CreateEvent Error!','Notice',MB_OK);
Exit;
end;
// 建立通信监视线程
Com_Thread:=CreateThread(nil,0,@CommWatch,nil,0,ThreadID);
if (Com_Thread=0) then
MessageBox(Handle,'No CraeteThread!',nil,mb_OK);
EscapeCommFunction(hNewCommFile,SETDTR);
Label1.Font.Color :=clRed;
Label1.Caption:='正在接收数据...!';
end;
procedure TForm1.Button4Click(Sender: TObject); // 停止通讯处理
begin
Label1.Font.Color :=clBlack;
Label1.Caption:='infomation';
Form1.Caption := IntToStr(ReceiveData);
Receive :=False;
CloseHandle(Read_Os.hEvent);
CloseHandle(Post_Event);
CloseHandle(hNewCommFile);
Button1.Enabled :=True;
Button2.Enabled :=True;
end;
end.
