获取随机字符串的方法 GetRandomString

方法1：推荐方便。

System.Hash 单元

Memo1.Lines.Add(THash.GetRandomString(50));

方法二（自己写的）：

function TStrApi.SuiJiString(const AWeiShu: Integer): string;
const
  SourceStr: string = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
var
  MyRep: string;
  I: Integer;
begin
  Randomize;
  for I := 1 to AWeiShu do
  begin
    //这里只所以必须加1,是因为SourceStr是从1开始的,而Random是从0开始的,SourceStr[0]就会报错,SourceStr[63]也会报错
    MyRep := MyRep + SourceStr[Random(61)+1];
  end;
  Exit(MyRep);
end;

PK结果，效率差不多。:

procedure TForm6.Button1Click(Sender: TObject);
var
  I: Integer;
  startTime: Cardinal;
  strResult: string;
begin
  startTime := GetTickCount;
  for I := 1 to 10000 do
  begin
    strResult := THash.GetRandomString(50);
  end;
  Label1.Caption := '耗时: ' + (GetTickCount - startTime).ToString;
end;

procedure TForm6.Button2Click(Sender: TObject);
const
  SourceStr: string = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
var
  strResult: string;
  I,K: Integer;
  startTime: Cardinal;
begin
  startTime := GetTickCount;
  for I := 1 to 10000 do
  begin
    Randomize;
    strResult := '';
    for K := 1 to 50 do
    begin
      //这里只所以必须加1,是因为SourceStr是从1开始的,而Random是从0开始的,SourceStr[0]就会报错,SourceStr[63]也会报错
      strResult := strResult + SourceStr[Random(61)+1];
    end;
  end;
  Label1.Caption := '耗时: ' + (GetTickCount - startTime).ToString;
end;

 http://www.cnblogs.com/del88/p/6911709.html