即时用户名检查与java bean和jquery远程验证器

Question

嗨，我在bootstrap中设计了注册表单，我使用远程验证器验证所有表单字段，我有registerdao.java方法，其中有checkusername布尔方法，检查所有行，如果用户名存在，它返回用户名字符串否则为false，我有checkusernameexists方法在注册servlet中，当您输入用户名字段时检查用户名。我不明白为什么我的代码没有显示任何东西。下面是代码不检查用户名对数据库和通知。如何编写javascript，使其检查用户名对数据或给我一些想法，如何使这段代码的工作?任何帮助都将非常感激。由于

ReegisterDao.javacheckUserName(String userName)抛出SQLException{String checkUserNameQuery = "select * from EmployeeDetails where USER_NAME='"+userName+"'";

  try{

 // preparing some objects for connection
currentCon = ConnectionManager.getConnection();
Statement stmt = currentCon.createStatement();
rs  = stmt.executeQuery(checkUserNameQuery);
boolean more = rs.next();
    // if user does not exist set the isValid variable to false
    return more;
     }

catch (InstantiationException | IllegalAccessException e){}

返回false;}

RegistrationServlet.java

public int checkUserNameExists(RegistrationBean user) throws SQLException{
        int a=RegistrationDao.Register(user);

    return a;
}

这是远程验证器的一部分，用于验证用户名

   username: {
                    validators: {
                        notEmpty: {
                            message: 'The username is required'
                        },
                        stringLength: {
                            min: 6,
                            max: 30,
                            message: 'The username must be more than 6 and less than 30 characters long'
                        },
                        regexp: {
                            regexp: /^[a-zA-Z0-9_.]+$/,
                            message: 'The username can only consist of alphabetical, number, dot and underscore'
                        },
                        remote:{
                            message:'This Username is already taken',
                            url:'https://localhost:8080/RegistrationServlet.java',
                            data:'username'
                        },
                        type:'POST'

                }   
                },

这是bootstrap用户名字段

的一部分

<div class="form-group">
    <label class="col-xs-2 control-label">Username</label>
    <div class="col-xs-4">
        <input type="text" class="form-control" name="username" placeholder="Username" />
    </div></div>

Answer 1

返回类型必须是合法的json格式。我认为，无论你从servlet返回到验证代码，都不是正确的json格式。使用inspect元素并在network TAB中查看它返回的结果。

首先你必须改变你的遥控器像这样

             remote: {
                        type: "POST",
                        url: 'RegistrationEmailCheck',//servlet
                        delay: 1000,
                        message: 'Your Message'
                    }

和servlet返回的数据如下所示

  public class RegistrationEmailCheck extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("application/json");
  PrintWriter out = response.getWriter();
JSONObject json = new JSONObject();
String availEmail = request.getParameter("email");
System.out.println(availEmail);
String SQL = "SELECT email FROM login WHERE email='" + availEmail + "'";
Connection con = DBInfo.getConn();
Statement st;
ResultSet rs;
try {
    st = con.createStatement();
    rs = st.executeQuery(SQL);

    if (rs.next()) {
        out.print("{"valid" : false }");
        json.put("valid", false);
        System.out.println("false");

    } else {
        out.print("{"valid" : true }");
        json.put("valid", true);
        System.out.println("true");

    }

} catch (Exception ex) {
    ex.printStackTrace();
} finally {
    out.close();
    }

}

}

此代码用于检查电子邮件