使用 mybatis-plus 操作后获得的数据类型为 Entity,但是前端界面往往需要展示一些其他的字段数据，此时就需要 将 Entity 转化为 Vo。
那么他们三者的关系是什么呢？面向的使用对象不同
entity: 对应数据库表模型
vo: 对应需要返回到前端的数据模型
dto: 对应后台内部调用的数据模型
package com.springblog.entity.vo;
import lombok.Data;
import java.io.Serializable;
@Data
public class BlogVo implements Serializable {
private String title;
/**
* 前端需要展示的其他字段
*/
private String otherProperty;
}package com.springblog.entity;
import com.baomidou.mybatisplus.annotation.TableName;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import java.time.LocalDateTime;
import java.io.Serializable;
import lombok.Data;
import javax.validation.constraints.NotBlank;
@Data
@TableName("m_blog")
public class BlogEntity implements Serializable {
private static final long serialVersionUID = 1L;
@TableId(value = "id", type = IdType.AUTO)
private Long id;
private String title;
private String description;
private String content;
private LocalDateTime created;
} @GetMapping("/one/{id}")
public R oneDefine(@PathVariable(name = "id") Long id) {
BlogEntity blogEntity = blogService.queryBlogById(id);
BlogVo blogVo = new BlogVo();
BeanUtil.copyProperties(blogEntity,blogVo);
blogVo.setOtherProperty("前端展示额外字段");
return R.ok().put("data", blogVo);
}如果采用最简单粗暴的方式，那么这个过程应该是这样的：
BeanUtil.copyProperties(source,target)将每一个Entity转化为vo过于繁琐，这很不好
@GetMapping("/list1")
public R list1(@RequestBody Map<String, Object> params) {
QueryWrapper<BlogEntity> queryWrapper = new QueryWrapper<>();
List<BlogEntity> list = blogMapper.selectList(queryWrapper);
ArrayList<BlogVo> voList = new ArrayList<>();
list.forEach(item->{
BlogVo voItem = new BlogVo();
BeanUtil.copyProperties(item,voItem);
voList.add(voItem);
});
return R.ok().put("data", voList);
}封装后，将 Entity 转化为 Vo
@GetMapping("/one/{id}")
public R oneDefine(@PathVariable(name = "id") Long id) {
BlogEntity blogEntity = blogService.queryBlogById(id);
BlogVo blogVo = ConvertUtil.entityToVo(blogEntity, BlogVo.class);
blogVo.setOtherProperty("前端展示额外字段");
return R.ok().put("data", blogVo);
}封装后，将 List<Entity> 转换为List<Vo>
@GetMapping("/list1")
public R list1(@RequestBody Map<String, Object> params) {
QueryWrapper<BlogEntity> queryWrapper = new QueryWrapper<>();
List<BlogEntity> list = blogMapper.selectList(queryWrapper);
List<BlogVo> blogVos = ConvertUtil.entityToVoList(list, BlogVo.class);
return R.ok().put("data", blogVos);
}
package com.springblog.common.utils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanUtils;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
/**
* @Author ifredom
* @Description 类型转换: Entity - Vo转换
* @Date 2022/5/10 15:59
* @Param [params]
**/
public class ConvertUtil {
public static final Logger logger = LoggerFactory.getLogger(ConvertUtil.class);
public static <T> T entityToVo(Object source, Class<T> target) {
if (source == null) {
return null;
}
T targetObject = null;
try {
targetObject = target.newInstance();
BeanUtils.copyProperties(source, targetObject);
} catch (Exception e) {
e.printStackTrace();
}
return targetObject;
}
public static <T> List<T> entityToVoList(Collection<?> sourceList, Class<T> target) {
if (sourceList == null) {
return null;
}
List<T> targetList = new ArrayList<>(sourceList.size());
try {
for (Object source : sourceList) {
T targetObject = target.newInstance();
BeanUtils.copyProperties(source, targetObject);
targetList.add(targetObject);
}
} catch (Exception e) {
logger.error("convert error ", e);
}
return targetList;
}
}
