问使用MySQL检查用户名和密码

EN

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                            
    String user = jTextField1.getText();
    char[] pass = jPasswordField1.getPassword();

    try
    {
        Class.forName("com.mysql.jdbc.Driver");
        con = DriverManager.getConnection("jdbc:mysql://localhost:3306/JEREN","root","");
        Statement stat = con.createStatement();
        String sql = "Select * from tbl_User Where username='" + user + "' and password='"+pass+"'";
        rs = stat.executeQuery(sql);
        while (rs.next())
        {
            if (user.equals(rs.getString("username")))
            {
                if (pass.equals(rs.getString("password")))
                {
                          JOptionPane.showMessageDialog(null,"Login Successfully");
                          main.getWindows();
                }
                          else
                                  {
                                      JOptionPane.showMessageDialog(null,"Incorrect Password");
            }
            else
            {
                JOptionPane.showMessageDialog(null,"Incorrect Login");
            }
        }
        stat.close();
        con.close();
    }
    catch (SQLException | HeadlessException e)
    {
        //e.printStackTrace();
        JOptionPane.showMessageDialog(null,"PROBLEM OCCURED !!!! ");
    } 
    catch (ClassNotFoundException ex) {
        Logger.getLogger(Users.class.getName()).log(Level.SEVERE, null, ex);
    }
 // TODO add your handling code here:
}