<p>
<table width="100%" border="0" class="normal">
  <tr>
    <td>请输入要运行文件的编号，完成之后按[运行]按钮。</td>
  </tr>
  <tr>
    <td>
      <input type="text" name="textfield" size="30" OnKeyDown="if (event.keyCode == 13) if (textfield.value != '') window.open('?filenum=' + textfield.value); else alert('请输入有效的文件编号.');">
      <input type="Button" name="Run" value="运行" OnClick="if (textfield.value != '') window.open('?filenum=' + textfield.value); else {alert('请输入有效的文件编号.');textfield.focus();textfield.select();}">
    </td>
  </tr>
</table>
<script language="JavaScript">
  textfield.focus();
  textfield.select();
</script>