springboot集成easyexcel实现导入导出

本文只实现比较简单的Excel导入导出，提供思路，以抛砖引玉
第一步：新建一个实体类User

@Data
public class User {

    @TableId
    @ExcelProperty(value = "序号") // 导出Excel 的列名
    private Integer id;
    
    @ExcelProperty(value = "姓名")
    private String name;
}

第二步：项目pom文件添加easyexcel的依赖

	<dependency>
		<groupId>com.alibabagroupId>
		<artifactId>easyexcelartifactId>
		<version>2.1.4version>
	dependency>
	<dependency>
		<groupId>javax.servletgroupId>
		<artifactId>servlet-apiartifactId>
		<version>2.5version>
	dependency>

第三步：引入导入导出工具类

/**
 * @author coder
 * @date 2021/12/7
 * 导出Excel工具类
*/
public class ExcelUtils {
    /**
    * 导出excel
    */
    public static void exportData(HttpServletResponse response, String excelName, String sheetName, Class clazz, List data) throws Exception {
        response.setContentType("application/vnd.ms-excel");
        response.setCharacterEncoding("utf-8");
        excelName = URLEncoder.encode(excelName, "UTF-8");
        response.setHeader("Content-disposition", "attachment;filename=" + excelName + ExcelTypeEnum.XLSX.getValue());
        EasyExcel.write(response.getOutputStream(), clazz).registerWriteHandler(new CustomCellWriteHandler()).sheet(sheetName).doWrite(data);
    }
}

导出excel设置列自动宽度

/**
 * @author 
 * @date 2021/12/7
 * 导出excel设置列自动宽度
 */
public class CustomCellWriteHandler extends AbstractColumnWidthStyleStrategy {

   private static final Logger LOGGER = LoggerFactory.getLogger(CustomCellWriteHandler.class);

   private Map<Integer, Map<Integer, Integer>> CACHE = new HashMap<>();

   @Override
   protected void setColumnWidth(WriteSheetHolder writeSheetHolder, List<CellData> cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {
      boolean needSetWidth = isHead || !CollectionUtils.isEmpty(cellDataList);
      if (needSetWidth) {
         Map<Integer, Integer> maxColumnWidthMap = CACHE.get(writeSheetHolder.getSheetNo());
         if (maxColumnWidthMap == null) {
            maxColumnWidthMap = new HashMap<>();
            CACHE.put(writeSheetHolder.getSheetNo(), maxColumnWidthMap);
         }

         Integer columnWidth = this.dataLength(cellDataList, cell, isHead);
         if (columnWidth >= 0) {
            if (columnWidth > 255) {
               columnWidth = 255;
            }

            Integer maxColumnWidth = maxColumnWidthMap.get(cell.getColumnIndex());
            if (maxColumnWidth == null || columnWidth > maxColumnWidth) {
               maxColumnWidthMap.put(cell.getColumnIndex(), columnWidth);
               writeSheetHolder.getSheet().setColumnWidth(cell.getColumnIndex(), columnWidth * 256);
            }

         }
      }
   }

   private Integer dataLength(List<CellData> cellDataList, Cell cell, Boolean isHead) {
      if (isHead) {
         return cell.getStringCellValue().getBytes().length;
      } else {
         CellData cellData = cellDataList.get(0);
         CellDataTypeEnum type = cellData.getType();
         if (type == null) {
            return -1;
         } else {
            switch (type) {
               case STRING:
                  return cellData.getStringValue().getBytes().length;
               case BOOLEAN:
                  return cellData.getBooleanValue().toString().getBytes().length;
               case NUMBER:
                  return cellData.getNumberValue().toString().getBytes().length;
               default:
                  return -1;
            }
         }
      }
   }
}

导入工具类

/**
  * 导入工具类
  * @author coder
  * @date 2021/12/7
  */
 public class ExcelListener<T> extends AnalysisEventListener<T> {

     //可以通过实例获取该值
     private List<Object> datas = new ArrayList<Object>();

     @Override
     public void invoke(Object o, AnalysisContext analysisContext) {
         datas.add(o);//数据存储到list，供批量处理，或后续自己业务逻辑处理。
         doSomething(o);//根据自己业务做处理
     }

     private void doSomething(Object object) {
     }

     public List<Object> getDatas() {
         return datas;
     }

     public void setDatas(List<Object> datas) {
         this.datas = datas;
     }

     @Override
     public void doAfterAllAnalysed(AnalysisContext analysisContext) {
         // datas.clear();//解析结束销毁不用的资源
     }

}

第四步：实现导入导出

@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {
    
    /**
     * 导出
     */
    @Override
	public void exportExcel(HttpServletResponse response) {
        List<User> list = baseMapper.selectUserList();
        try {
            ExcelUtils.exportData(response,"用户信息", "sheet1", User.class, list);
        } catch (Exception e) {
            e.printStackTrace();
        }
	}

    /**
     * EasyExcel实现导入
     * @param file
     * @return
     */
    @Override
    @SneakyThrows
    public boolean importExcel(MultipartFile file) {
        //获取文件流
        InputStream inputStream = file.getInputStream();
        //实例化实现了AnalysisEventListener接口的类
        ExcelListener listener = new ExcelListener();
        EasyExcelFactory.read(inputStream, User.class, listener).headRowNumber(1).build().readAll();
        //获取数据
        List<User> list = listener.getDatas();
        return userService.saveBatch(list);
    }
}