Can find the below code snippet might helpful for you.
Controller GET/POST mapping:
@RequestMapping(value = "/registration", method = RequestMethod.GET)
public String registartionPage(Model model) {
Registration registration = new Registration();
model.addAttribute("registration", registration);
return "registarion/registarion";
}
@RequestMapping(value = "/user/new-user-registrn", method = RequestMethod.POST)
public String newUserRegistrn(Model model, @ModelAttribute("registration") 
Registration registration, RedirectAttributes redirectAttributes) {
try {
    StarUser user = starSecurityService.findSysUserName(registration.getUserName());
    if (user != null) {
        throw new Exception("User Already Exist. Please try with different User Name");
    }
    user = (StarUser) starUtilService.save(setStarUser(registration));
    model.addAttribute("registration", registration);
    if (user != null) {
        redirectAttributes.addAttribute("starMessage",
            "Your Account is successfully created !! Login to Access the Application");
        return "redirect:/";
    }
} catch (Exception e) {
    model.addAttribute(STAR_MESSAGE, e.getMessage());
}
return "registarion/registarion";
}
Thymeleaf Content:
<form class="form-horizontal col-sm-12" method="POST" th:action="@{/user/new-user-registrn}" th:object="${registration}">
<div class="row">
    <div class="form-group col-md-12">
        <div class="star-reg-header">New User Registration</div>
    </div>
    <div class="star-reg-body">
        <div class="form-group col-sm-4">
            <label class="required">First Name: </label>
            <input type="text" class="form-control required" th:field="*{firstName}" required="required" />
        </div>
        <div class="form-group col-sm-4">
            <label class="required">Last Name: </label>
            <input type="text" class="form-control" th:field="*{lastName}" required="required" />
        </div>
        <div class="form-group col-sm-4">
            <label class="required">User Name: </label>
            <input type="text" class="form-control" th:field="*{userName}" required="required" />
        </div>
        <div class="form-group col-sm-4">
            <label class="required">Password: </label>
            <input type="password" class="form-control" th:field="*{password}" required="required" />
        </div>
        <div class="form-group col-sm-4">
            <label class="required">Email: </label>
            <input type="text" class="form-control" th:field="*{email}" required="required" />
        </div>
    </div>
</div>
<div class="form-group col-md-12">
    <label class="col-sm-2"></label>
    <div class="col-sm-10">
        <button type="submit" class="btn btn-info">Submit</button>
    </div>
</div>
Java Bean class
public class Registration {
 protected String firstName;
 protected String lastName;
 protected String userName;
 protected String password;
 protected String email;
 //Setter and Getter
}