【后端架构完善与接口开发】006-制作CopyUtil封装BeanUtils

朱雀 2023-10-03 13:03 15阅读 0赞

### 文章目录 ###

*   *  8、制作CopyUtil封装BeanUtils
     *   *  第一步：新建 util 包，创建 CopyUtil 类
         *  第二步：修改 EBookService
         *  第三步：运行测试

## 8、制作CopyUtil封装BeanUtils ##

### 第一步：新建 util 包，创建 CopyUtil 类 ###

package com.zibo.wiki.util;
    
    import org.springframework.beans.BeanUtils;
    import org.springframework.util.CollectionUtils;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class CopyUtil {
        
    
        /**
         * 单体复制
         */
        public static <T> T copy(Object source, Class<T> clazz) {
        
            if (source == null) {
        
                return null;
            }
            T obj;
            try {
        
                obj = clazz.newInstance();
            } catch (Exception e) {
        
                e.printStackTrace();
                return null;
            }
            BeanUtils.copyProperties(source, obj);
            return obj;
        }
    
        /**
         * 列表复制
         * 老师是这么写的：List source
         * 我觉得提示难看，改成了：List<?> source
         */
        public static <T> List<T> copyList(List<?> source, Class<T> clazz) {
        
            List<T> target = new ArrayList<>();
            if (!CollectionUtils.isEmpty(source)){
        
                for (Object c: source) {
        
                    T obj = copy(c, clazz);
                    target.add(obj);
                }
            }
            return target;
        }
    
    }

### 第二步：修改 EBookService ###

package com.zibo.wiki.serivce;
    
    import com.zibo.wiki.domain.Ebook;
    import com.zibo.wiki.domain.EbookExample;
    import com.zibo.wiki.mapper.EbookMapper;
    import com.zibo.wiki.req.EbookReq;
    import com.zibo.wiki.resp.EbookResp;
    import com.zibo.wiki.util.CopyUtil;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    
    import java.util.List;
    
    @Service
    public class EBookService {
        
    
        @Autowired
        private EbookMapper ebookMapper;
    
        public List<EbookResp> list(EbookReq req){
        
            EbookExample ebookExample = new EbookExample();
            // 查询条件
            EbookExample.Criteria criteria = ebookExample.createCriteria();
            criteria.andNameLike("%" + req.getName() + "%");
            List<Ebook> ebookList = ebookMapper.selectByExample(ebookExample);
            // List<EbookResp> respList = new ArrayList<>();
            // for (Ebook ebook : ebookList) {
        
            //     EbookResp ebookResp = new EbookResp();
            //     BeanUtils.copyProperties(ebook,ebookResp); // 拷贝
            //     respList.add(ebookResp);
            // }
            return  CopyUtil.copyList(ebookList, EbookResp.class);
        }
    
    }

### 第三步：运行测试 ###

![image-20210718225829280][]

[image-20210718225829280]: https://img-blog.csdnimg.cn/img_convert/f8f4d2cef4e786b4f34b4e3bea8b55b8.png