我发现Delphi下没有很好用的只能输入数字的控件。所以自己写了一个（D7）。

菜鸟一个，希望大家多多指点。呵呵。。。

unit ComerMaskEdit;

interface

uses
Windows, Messages, Graphics, Forms,
SysUtils, Classes, Controls, StdCtrls;

type
TComerMaskEdit = class(TEdit)
private
FMdNumber: string;
FIpo : Integer;
FLen : Integer;
procedure SetMdNumber(const Value: string);
procedure WMPaste(var Message: TMessage); message WM_PASTE;
{ Private declarations }
protected
procedure CreateWnd;override;
{ Protected declarations }
public
constructor Create(AOwner:TComponent);override;
procedure DoEnter(); override;
procedure DoExit(); override;
procedure KeyPress(var Key: Char); override;
procedure KeyDown (var Key: Word; Shift: TShiftState);override;
{ Public declarations }
published
property MdNumber:string read FMdNumber write SetMdNumber;
{ Published declarations }
end;

procedure Register;

implementation

procedure Register;
begin
RegisterComponents('Standard', [TComerMaskEdit]);
end;

{TComerMaskEdit}

constructor TComerMaskEdit.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
Font.Size :=12;
Font.Name:='宋体';
Font.Charset:=GB2312_CHARSET;
FMdNumber := '';
end;

procedure TComerMaskEdit.CreateWnd;
var
I, k : Integer;
S, Str : string;
begin
inherited;
if not Enabled then
Font.Color := clNavy;
Font.Size :=12;
Font.Name :='宋体';
Font.Charset :=GB2312_CHARSET;
if FMdNumber <> '' then
begin
I := Pos(',',FMdNumber);
if I > 0 then
begin
    S := Copy(FMdNumber,1,I-1);
    FIpo := StrToInt(Copy(FMdNumber,I+1,Length(FMdNumber)-I));
    for k:=1 to FIpo do
    Str := Str + '0';
    Text := '.' + Str;
end
else
  begin
     S := FMdNumber;
      FIpo := 0;
      Text := '';
  end;
     MaxLength := StrToInt(S);
     FLen := MaxLength;
     imeMode := imClose;
  end;
end;

procedure TComerMaskEdit.SetMdNumber(const Value: string);
var
S : string;
begin
if Value <> '' then
begin
  S := StringReplace(Value,',','',[rfIgnoreCase]);
  try
     StrToInt(S);
       except
         Application.MessageBox('属性值设置不对！','错误',MB_OK+MB_ICONError);
       FMdNumber := '';
     Exit;
   end;
end;
FMdNumber := Value;
end;

procedure TComerMaskEdit.DoEnter();
begin
   inherited;
   SelStart := 0;
end;

procedure TComerMaskEdit.DoExit();
begin
  if (FIpo>0) and (Pos('.',Text)=0) then
      Text := Text + '.' + StringOfChar('0',FIpo)
    else
  inherited;
end;

procedure TComerMaskEdit.KeyPress(var Key: Char);
var
I, k : Integer;
AfterDot, BeforSelStart : string;
//, AfterSelStart,
   Str : string;
   TmpText : string;
   iSelStart: Integer;
//BeforComma, AfterComma : String;
begin
   //如果有多个字符被选中
   if SelLength > 0 then
     SelStart := 0
   else
   begin
     if FMdNumber <> '' then
      begin
        if (Length(Text)=0) and (FIpo>0) then
         begin
           for k:=1 to FIpo do
             Str := Str + '0';
             Text := '.' + Str;
         end;
         case Key of
      #13:
   inherited;
 '-':
begin
if (SelStart<>0) or (Pos('-',Text)>0) then
Key := #0
else
//MaxLength := MaxLength + 1;
inherited;
end;
#8:
begin
I := Pos('.',Text);
if (I > 0) and (SelStart>I) then
begin
   key := #0;
   iSelStart := SelStart;
   TmpText := Text;
   BeforSelStart := Copy(TmpText,1,iSelStart-1);
   Text := BeforSelStart + Copy(TmpText,iSelStart+1,Length(TmpText)-iSelStart) + '0';
   SelStart := iSelStart - 1;
end
else if (I > 0) and (SelStart=I) then
  begin
     key := #0;
     iSelStart := SelStart;
     SelStart := iSelStart - 1;
  end
else
  inherited;
end;
'0'..'9':
begin
I := Pos('.',Text);
//限制位数
if I > 0 then
begin
if SelStart = Length(Text) then
key := #0
else
begin
   AfterDot := Copy(Text,I+1,Length(Text)-FIpo);
     if Length(AfterDot) > FIpo then
         key := #0
           else if SelStart >= I then
   begin
     iSelStart := SelStart;
     TmpText := Text;
     BeforSelStart := Copy(TmpText,1,iSelStart);
Text := BeforSelStart + Copy(TmpText,iSelStart+2,Length(TmpText)-iSelStart-1);
SelStart := iSelStart;
    end
    else
    inherited;
end;
end
else if (I<=0) and (FIpo>0) then //这种情况基本不存在
begin
if Length(Text) >= FLen-FIpo-1 then
 key := #0
  else
   inherited;
   end
      else //FIpo=0
      inherited;
end;

'.':
begin
Key := #0;
if FIpo>0 then
    SelStart := Pos('.',Text);
    end;
    else
    Key := #0;
    end;
    end
    else
    //Key := #0;
    inherited;
end;
end;

procedure TComerMaskEdit.KeyDown(var Key: Word; Shift: TShiftState);
var
I : Integer;
BeforSelStart : string;
TmpText : string;
iSelStart: Integer;
begin
//如果有多个字符被选中
if SelLength > 0 then
begin
Key := 0;
SelStart := 0;
end
else
  begin
    if FMdNumber <> '' then
    begin
        if Key=VK_DELETE then
         begin
           I := Pos('.',Text);
         if (I > 0) and (SelStart>=I) then
begin
   key := 0;
   iSelStart := SelStart;
   TmpText := Text;
   BeforSelStart := Copy(TmpText,1,iSelStart);
    if (SelStart=Length(Text)) then
        Text := BeforSelStart + Copy(TmpText,iSelStart+2,Length(TmpText)-iSelStart-1)
    else
       Text := BeforSelStart + Copy(TmpText,iSelStart+2,Length(TmpText)-iSelStart-1) + '0';
       SelStart := iSelStart;
end
else if (I > 0) and (SelStart=I-1) then
    begin
       key := 0;
         iSelStart := SelStart;
       SelStart := iSelStart + 1;
    end;
end
else if (Key=VK_TAB) or (Key=VK_LEFT) or (Key=VK_UP) or (Key=VK_RIGHT) or (Key=VK_DOWN) or (Key=VK_END) or (Key=VK_HOME) then
 inherited
   else
    Key := 0;

   end
   else
       inherited;
   end;
end;

procedure TComerMaskEdit.WMPaste(var Message: TMessage);
begin
    if FMdNumber='' then
        inherited;
    end;

end.