Jquery实现页面上所有的checkbox只能选中一个

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>checkBox4radio.html</title>
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <script type="text/javascript" src="jquery.js"></script>
    <script type="text/javascript">
        $(function () {
            var allBox = $(":checkbox");
            //var allBox  = $("#div input:checkbox");
            allBox.click(function () {
                allBox.removeAttr("checked");
                $(this).attr("checked", "checked");
            });
            $(":button").click(function () {
                alert($(":checkbox:checked").val());
            });
        });
    </script>

  </head>

  <body>
      <input type="button" value="remove" />
    <div>
        <input type="checkbox" value="1"/>
        <input type="checkbox" value="2"/>
        <input type="checkbox" value="3"/>
        <input type="checkbox" value="4"/>
    </div>
  </body>
</html>