java中VO的使用解析_Java教程

java中VO的使用

场景

现在我们需要从数据库中查询用户列表t_user，对应的实体类如下：

				?

									import io.swagger.annotations.ApiModelProperty;

									public class User {

									    @ApiModelProperty(value = "用户id")

									    private String userId;

									    @ApiModelProperty(value = "用户名称")

									    private String name;

									    /**

									     * 状态参考 UserStatus

									     */

									    @ApiModelProperty(value = "用户状态  1已认证，2 认证中，3未通过认证，7未提交认证")

									    private Integer status;

									    @ApiModelProperty(value = "头像地址")

									    private String headPicFileName;

									    @ApiModelProperty(value = "手机号")

									    private String telephone;

									    /**

									     * 用户级别 0到期 1游客 2临时用户 3认证用户 参考health com.dachen.health.commons.vo.User

									     */

									    private Integer userLevel;

									    @ApiModelProperty(value = "医生信息")

									    private Doctor doctor;

									    get/setXxx().... 

									    @Override

									    public boolean equals(Object o) {

									        if (this == o) {

									            return true;

									        }

									        if (o == null || getClass() != o.getClass()) {

									            return false;

									        }

									        User user = (User) o;

									        return userId != null ? userId.equals(user.userId) : user.userId == null;

									    }

									}

但是前端页面需要展示更多个关于用户的消息，如用户的角色Role,而User实体类中的信息不全，为了返回更多的信息，

有两种做法：

1.直接在user类中添加需要的信息属性
2.创建一个新类UserVO extends User，只在UserVO中添加更多属性，而且以VO结尾表示用于返回前端的数据

如果采用第一种做法，User类可能会越来越大，也不方便后期维护，而且User类作为对数据库表的映射，添加冗余的属性反而会破坏这种映射关系，采取第二种方法，更加清晰明确.

现在采用第二种方法，假设从数据中查出user列表：

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									List<User> users = userServiceImpl.findUsersByIds(userIds);

									//将User列表转换为UserVO列表:

									List<CircleUserVO> circleUserVOs=BeanUtil.copyList(users,CircleUserVO.class);

									//给UserVO添加角色属性

									wrapRole(circleUserVOs,circleId);

									wrapRole(List<CircleUserVO> circleUserVOs,Long circleId){

									    //所有角色权限

									    List<CircleUserVO> circleUserVOList = circleMemberRoleMapper.selectAllMemberRoleByCircleId(circleId);

									    for (CircleUserVO circleUserVO:circleUserVOList){

									        for (CircleUserVO circleUserVO1:circleUserVOs){

									            if(circleUserVO.getUserId().equals(circleUserVO1.getUserId())){

									                circleUserVO1.setRole(circleUserVO.getRole());

									            }

									        }

									    }

									}

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									package com.dachen.circle.model.vo;

									import com.dachen.circle.model.inner.User;

									import io.swagger.annotations.ApiModelProperty;

									public class CircleUserVO extends User{

									    @ApiModelProperty(value = "在该圈子的角色1：管理员 2：圈主（负责人）3：顾问 逗号拼接 多个角色 可同时为管理员，圈主，顾问")

									    private String role;

									    @ApiModelProperty(value = "0否 1是 永久免费")

									    private Integer permanentFree;

									    @ApiModelProperty(value = "1正常 2欠费")

									    private Integer arrearageStatus;

									    @ApiModelProperty(value = "过期时间 月数")

									    private Integer expirationMonth;

									    @ApiModelProperty(value = "医院名称")

									    private String hospital;

									    @ApiModelProperty(value = "科室")

									    private String departments;

									    @ApiModelProperty(value = "职称")

									    private String title;

									    @ApiModelProperty(value = "简介")

									    private String introduction;

									    @ApiModelProperty(value = "排序字母 A-Z Z1为#")

									    private String letter;

									   get/setXxx(); 

									}

				?

									package com.dachen.util;

									import org.springframework.beans.BeanUtils;

									import java.util.ArrayList;

									import java.util.List;

									public class BeanUtil {

									     public static <T> T copy(Object poObj,final Class <T>voClass)

									     {

									         T voObj =null;

									         try {

									             voObj = voClass.newInstance();

									             BeanUtils.copyProperties(poObj, voObj);

									             return voObj;

									         } catch (InstantiationException | IllegalAccessException e) {

									             e.printStackTrace();

									         }

									         return null;

									     }

									     public static <T> List <T> copyList(List <? extends Object> poList ,final Class <T>voClass){

									        List<T> voList=new ArrayList<T>();

									        T voObj =null;

									        for(Object poObj:poList){

									            try {

									                voObj = voClass.newInstance();

									                BeanUtils.copyProperties(poObj, voObj);

									                voList.add(voObj);

									            } catch (InstantiationException | IllegalAccessException e) {

									                e.printStackTrace();

									            }

									            System.out.println(voObj);

									        }

									        return voList;

									    }

									}