如何使用java检查mysql数据库中的现有电子邮件ID

Question

我想检查用户输入的电子邮件ID是否已在数据库中可用。

我使用了以下脚本：

<script src="jquery.js" type="text/javascript"></script>
    <script type="text/javascript">
          $(document).ready(function(){
              $(".email").change(function(){
                  var email = $(this).val();
                  if(email.length >= 3){
                      $(".status").html("<img src='images/loading.gif'><font color=gray> Checking availability...</font>");
                       $.ajax({
                          type: "POST",
                          url: "checkemail.do",
                          data: "email="+ email,
                          success: function(msg){

                              $(".status").ajaxComplete(function(event, request, settings){

                                  $(".status").html(msg);
    <input id="emailsignup" name="emailid" type="text"
                                placeholder="mysupermail@mail.com" />
                                <input type="text" class="email" />
                            &nbsp;
                            <span class="status"></span>
                        </p>
                              });
                          }
                      }); 
                  }
                  else{

                      $(".status").html("<font color=red>Username should be <b>3</b> character long.</font>");
                  }

              });
          });
        </script>







<label for="emailsignup" class="youmail">
                                Your email
                            </label>
                            <input id="emailsignup" name="emailid" type="text"
                                placeholder="mysupermail@mail.com" />
                                <input type="text" class="email" />
                            &nbsp;
                            <span class="status"></span>

控制器类中的

方法。我正在尝试从请求中获取emailid并调用服务方法并进一步调用模型类。

@RequestMapping(value="/checkemail.do")
public String checkEmail(HttpServletRequest req){
  String emailid= req.getParameter("emailid");
    service.checkemail(emailid);
    return "email";

}