推荐篇：原来阿里也对excel情有独钟( 二 ) _实体类

注：导入和导出时使用到的User实体类而不是普通的实体类，需要添加该包下的注解，才可在导入或导出的时候和excel中的列映射；
如果实体类中存在许多字段而导出时有些字段不需要就需要在该字段上添加@注解；就不会使用该字段；如果该字段不使用并且也没有添加的任何注解，那么导出时也会将该字段导出到excel表格中；
import com.alibaba.excel.annotation.ExcelProperty;import java.math.BigDecimal;/*** @author Mr.Gu* @date 2020/10/21 9:20* @function :**/public class User {@ExcelProperty(value = "http://www.kingceram.com/post/编号",index = 0)private Integer number;@ExcelProperty(value = "http://www.kingceram.com/post/姓名",index = 1)private String name;@ExcelProperty(value = "http://www.kingceram.com/post/性别",index = 2)private String sex;@ExcelProperty(value = "http://www.kingceram.com/post/年龄",index = 3)private Integer age;@ExcelProperty(value = "http://www.kingceram.com/post/分数",index = 4)private BigDecimal score;//getter/setter方法
最后，使用该工具类导出的excel如下：
非常简单，好用的一个excel工具类。记录完成。
设置单元格自适应宽度：
import com.alibaba.excel.enums.CellDataTypeEnum;import com.alibaba.excel.metadata.CellData;import com.alibaba.excel.metadata.Head;import com.alibaba.excel.util.CollectionUtils;import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;import com.alibaba.excel.write.style.column.AbstractColumnWidthStyleStrategy;import org.apache.poi.ss.usermodel.Cell;import java.util.HashMap;import java.util.List;import java.util.Map;public class ExcelCellWriteHandler extends AbstractColumnWidthStyleStrategy {private Map> CACHE = new HashMap<>();@Overrideprotected void setColumnWidth(WriteSheetHolder writeSheetHolder, List cellDataList, Cell cell, Head head, Integer relativeRowIndex, Boolean isHead) {boolean needSetWidth = isHead || !CollectionUtils.isEmpty(cellDataList);if (needSetWidth) {Map 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 cellDataList, Cell cell, Boolean isHead) {if (isHead) {return cell.getStringCellValue().getBytes().length;} else {CellData cellData = http://www.kingceram.com/post/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;}}}}}
将该类作为配置类放到项目中；
【推荐篇：原来阿里也对excel情有独钟】使用方式：