poi operation cell

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.FileOutputStream;
import java.io.IOException;

/**
 * @author longrong.lang
 * @version 1.0
 * @description
 * @date 2020/9/15 9:32
 */
public class MergeCellDemo {
    public static void main(String[] args) throws IOException {
        //新建工作簿
        XSSFWorkbook xssfWorkbook = new XSSFWorkbook();

        //新建工作表
        XSSFSheet sheet = xssfWorkbook.createSheet("工作表1");
        //指定合并开始行、合并结束行 合并开始列、合并结束列
        CellRangeAddress rangeAddress = new CellRangeAddress(0, 0, 0, 1);
        //添加要合并地址到表格
        sheet.addMergedRegion(rangeAddress);
        //创建行，指定起始行号，从0开始
        XSSFRow row = sheet.createRow(0);
        //创建单元格，指定起始列号，从0开始
        XSSFCell cell = row.createCell(0);
        //设置单元格内容
        cell.setCellValue("我是合并后的单元格");
        //创建样式对象
        CellStyle style = xssfWorkbook.createCellStyle();
        //设置样式对齐方式：水平\垂直居中
        style.setAlignment(HorizontalAlignment.CENTER);
        style.setVerticalAlignment(VerticalAlignment.CENTER);
        //设定填充单色
        style.setFillPattern(FillPatternType.SOLID_FOREGROUND);
        //设定背景颜色
        style.setFillForegroundColor(IndexedColors.PINK.getIndex());
        //为指定单元格设定样式
        cell.setCellStyle(style);
        FileOutputStream fileOutputStream = new FileOutputStream("d:\\MergeCellDemo.xlsx");
        xssfWorkbook.write(fileOutputStream);
        fileOutputStream.close();
//FileOutputStream fos = new FileOutputStream(new File("C:\\信息.xlsx"));
           // wb.write(fos);
            //fos.close();
           // wb.close();
    }
}

Recently, there is a requirement in the project that the exported excel has multiple data validity verification functions. At first, it refers to the use of POI on the Internet to add data validity verification to Excel . The core code is roughly as follows

However, in the process of using it, I found that once the validity list exceeds 255 characters, the entire Excel will be invalid. I searched for a long time, and referred to another solution on the Internet when the value of the drop-down list exceeds 255 when exporting excel from poi. The core code is as
follows

         XSSFSheet sheet = wb.createSheet(sheetName);
         //获取所有sheet页个数
         int sheetTotal = wb.getNumberOfSheets();
         String hiddenSheetName = "hiddenSheet" + sheetTotal;
         XSSFSheet hiddenSheet = wb.createSheet(hiddenSheetName);
         Row row;
         //写入下拉数据到新的sheet页中
         for (int i = 0; i < selectList.length; i++) {
             row = hiddenSheet.createRow(i);
             Cell cell = row.createCell(0);
             cell.setCellValue(selectList[i]);
         }
         //获取新sheet页内容
         String strFormula = hiddenSheetName + "!$A$1:$A$65535";   //hiddenSheetName + ! 定位到用来加载列的新的sheet页，后面则是A列的1-65535为有效性List条件
         XSSFDataValidationConstraint constraint = new XSSFDataValidationConstraint(DataValidationConstraint.ValidationType.LIST,strFormula);
         // 设置数据有效性加载在哪个单元格上,四个参数分别是：起始行、终止行、起始列、终止列
         CellRangeAddressList regions = new CellRangeAddressList(0,65535, columnIndex, columnIndex);
         // 数据有效性对象
         DataValidationHelper help = new XSSFDataValidationHelper((XSSFSheet) sheet);
         DataValidation validation = help.createValidation(constraint, regions);
         sheet.addValidationData(validation);
         //将新建的sheet页隐藏掉
         wb.setSheetHidden(sheetTotal, true);

Problem solved successfully! ! !

	XSSFDataValidationConstraint dvConstraint = (XSSFDataValidationConstraint) dvHelper
			.createExplicitListConstraint(explicitListValues);
	CellRangeAddressList addressList = new CellRangeAddressList(firstRow, lastRow, firstCol, lastCol);
	XSSFDataValidation validation = (XSSFDataValidation) dvHelper.createValidation(dvConstraint, addressList);
	validation.setSuppressDropDownArrow(true);
	validation.setShowErrorBox(true);
	sheet.addValidationData(validation);