anchor.diff:          <form class="form-signin" method="post" action="${basePath }login">
               <h2 class="form-signin-heading">请登录：<p style="color: red" id="errorinfo_id">${returninfo }</p></h2>
               <div class="form-group" id="Id_div">
  -                <input type="number" name="username" class="form-control" id="inputID" placeholder="学号" required
  +                <input type="text" name="username" class="form-control" id="inputID" placeholder="学号" required
                          autofocus>
                   <span class="glyphicon glyphicon-remove form-control-feedback" aria-hidden="true"></span>
               </div>
  
positive.code: <script src="${basePath }js/base.js"></script>
  <script>
      $(function () {
          var height=$(window).height(); //浏览器当前窗口可视区域高度
          var section_height=$("section").outerHeight(true);
          $("section").css("margin-top",(height/2)-(section_height/2));
          $(window).resize(function(){
              var height=$(window).height(); //浏览器当前窗口可视区域高度
              var section_height=$("section").outerHeight(true);
              $("section").css("margin-top",(height/2)-(section_height/2));
          });
          var idlength = 0;
          var passwdlength = 0;
          $("#inputID").blur(function () {
              var inputID = $(this).val();
              idlength = inputID.length;
              if (idlength !== 12) {
                  $("#errorinfo_id").text("学号长度为12位数字，请输入正确的学号！");
                  $("#Id_div").addClass("has-error has-feedback");
              }
              else {
                  $("#errorinfo_id").text("");
                  $("#Id_div").removeClass("has-error has-feedback");
              }
          });
          $("#inputPassword").blur(function () {
              var inputPassword = $(this).val();
  
negative.code:         .form-control {
              margin-bottom: 20px;
          }
  
          .col-md-6 {
              margin-top: 1em;
          }
      </style>
  