一个JavaBean和DTO转换的优秀案例

public abstract class Converter<A, B>  {
    protected abstract B doForward(A a);
    protected abstract A doBackward(B b);
}

import lombok.Data;
import org.bson.types.ObjectId;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

@Data
@Document(collection = "user")
public class User {
    @Id
    private ObjectId id;

    private String username;
    private String password;
}

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.beans.BeanUtils;
import study.Converter;

import javax.validation.constraints.NotNull;

@NoArgsConstructor
@AllArgsConstructor(staticName = "of")
@Data
public class UserDTO {
    /**
     * AllArgsConstructor注解和NotNull注解配合使用，参数不为null
     */
    @NotNull(message = "username is null")
    private String username;
    @NotNull(message = "password is null")
    private String password;

    public User convertToUser(){
        UserDTOConvert userDTOConvert = new UserDTOConvert();
        User convert = userDTOConvert.doForward(this);
        return convert;
    }

    public UserDTO convertFor(User user){
        UserDTOConvert userDTOConvert = new UserDTOConvert();
        UserDTO convert = userDTOConvert.doBackward(user);
        return convert;
    }

    private static class UserDTOConvert extends Converter<UserDTO, User> {
        @Override
        protected User doForward(UserDTO userDTO) {
            User user = new User();
            BeanUtils.copyProperties(userDTO,user);
            return user;
        }

        @Override
        protected UserDTO doBackward(User user) {
            UserDTO userDTO = new UserDTO();
            BeanUtils.copyProperties(user,userDTO);
            return userDTO;
        }
    }
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


import javax.validation.Valid;

@RestController
@RequestMapping(value = "/api/user")
public class UserController {

    @Autowired
    private UserService userService;

    @PostMapping
    public UserDTO addUser(@Valid UserDTO userDTO){
        User user = userDTO.convertToUser();


        User addUser = userService.addUser(user);

        UserDTO result = userDTO.convertFor(addUser);
        return result;
    }
}