DTO模式：在两个对象之间复制属性的最佳方式 [英] DTO pattern: Best way to copy properties between two objects

问题描述

在我的应用程序架构中，我通常通过服务层将对象或对象列表从数据访问层发送到Web层，其中这些对象从 DAO 对象 DTO 对象，反之亦然。 Web层没有对DAO对象的任何访问权限，并且DAO层不使用DTO。

In my application's architecture I usually send the object or list of objects from the data access layer to the web layer via the service layer, in which these objects get transformed from a DAO object to a DTO object and vice versa. The web layer don't have any access to DAO objects and the DAO layer do not use DTOs.

为了演示，我通常将代码编写为：

To demonstrate, I usually write the code as:

@Transactional(readOnly = true)
public List<UserDTO> getAllUserAsUserDTO() {
    List<UserDTO> userDTOs = new ArrayList<UserDTO>();

    for(User user : getAllUser()) {
        userDTOs.add(constructUserDTO(user));
    }

    return userDTOs;
}

private UserDTO constructUserDTO(User user) {
    UserDTO userDTO = new UserDTO();
    userDTO.setFullName(user.getFullName());
    userDTO.setId(user.getId());
    userDTO.setUsername(user.getUsername());
    userDTO.setRole(user.getRole());
    userDTO.setActive(user.isActive());
    userDTO.setActiveText(user.isActive() ? "Active" : "Inactive");
    return userDTO;
}

这里的用户是数据库实体：

Here the user is the database entity:

@javax.persistence.Entity
@Table(name = "USER")
public class User extends Entity {

    @Transient
    private static final long serialVersionUID = -112950002831333869L;

    private String username;
    private String fullName;
    private boolean active;
    private String role;
    // other fields

    public User() {
        super();
    }

    @NaturalId
    @Column(name = "USERNAME", nullable = false)
    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    @Column(name = "FULL_NAME")
    public String getFullName() {
        return fullName;
    }

    public void setFullName(String fullName) {
        this.fullName = fullName;
    }

    @Column(name = "ACTIVE", nullable = false)
    public boolean isActive() {
        return active;
    }

    public void setActive(boolean active) {
        this.active = active;
    }

    @Column(name = "ROLE")
    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }
}

这是UserDTO：

public class UserDTO extends BaseDTO {

    private static final long serialVersionUID = -3719463614753533782L;

    private String username;
    private String fullName;
    private String role;
    private String activeText;
    private Boolean active;
    //other properties

    public UserDTO() {
        super();
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getFullName() {
        return fullName;
    }

    public void setFullName(String fullName) {
        this.fullName = fullName;
    }

    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }

    public String getActiveText() {
        return activeText;
    }

    public void setActiveText(String activeText) {
        this.activeText = activeText;
    }

    public Boolean getActive() {
        return active;
    }

    public void setActive(Boolean active) {
        this.active = active;
    }
}

所以我想知道这是否是唯一的方法复制两个对象之间的属性。我想我不确定。我也在使用 lambdaj ，所以我在这个API中有一个方法可以复制所有这些属性可以创建其他对象的列表吗？

So I was wondering if this is the only way to copy properties between two objects. I guess I am not sure. Also I am using lambdaj, so is there a method in this API by which I can copy all these properties to create list of other objects?

这个主题可能听起来很主观，但我真的想从你的专家那里知道对象从一个转换的方式可以在最大字段具有相同字符串的情况下完成另一个表单。

This topic may be sounds subjective, but I really want to know from you experts the ways by which the transformation of object from one form to another can be done where the maximum fields are having same string.

推荐答案

您可以查看推土机这是一个

Java Bean到Java Bean映射器，递归地将数据从一个对象复制到另一个对象。通常，这些Java Bean将具有不同的复杂类型。

Java Bean to Java Bean mapper that recursively copies data from one object to another. Typically, these Java Beans will be of different complex types.

另一个更好的链接......

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