数据导出Excel，动态列

今天碰到一个需求，要求将用户回答的问卷及问题导出Excel表格，问卷对应的问题数量不一致，需要动态添加列表头，简单记录。

要导出Excel需要添加poi.jar包

用户-问卷实体（固定列）：

package com.lwl.bean;

import com.util.annotation.BeanField;
import lombok.Data;

import java.sql.Timestamp;
import java.util.List;

/**
 * 问卷实体（用于导出excel）
 * @author linwenli
 */
@Data
public class HyMktUserQuesBean {


    @BeanField("用户名")
    private String wechatName;
    @BeanField("联系电话")
    private String telephone;
    @BeanField("主题名称")
    private String questionName;
    @BeanField("参与时间")
    private Timestamp createTime;
    @BeanField("问题内容")
    private List<HyMktUserQuesAnswerBean> hyMktUserQuesAnswerBeans;
}

用户-问卷问题实体（动态列）：

package com.lwl.bean;

import com.util.annotation.BeanField;
import lombok.Data;

/**
 * 问题及用户答案
 * @author linwenli
 */
@Data
public class HyMktUserQuesAnswerBean {
    @BeanField("问题名称")
    private String problemName;
    @BeanField("答案")
    private String optionName;
}

导出方法：

package com.lwl.util;

import com.lwl.bean.HyMktUserQuesAnswerBean;
import com.lwl.bean.HyMktUserQuesBean;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.usermodel.*;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;
import java.util.List;

public class ExcelUtil {

    /**
     * 根据List<HyMktUserQuesBean> 导出数据到Excel
     * @author linwenli
     * @date 2019/5/09 15:27
     * @param response
     * @param fileName
     * @param hyMktUserQuesBeans
     * @throws IOException
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     */
    public static void writeExcel(HttpServletResponse response, String fileName, List<HyMktUserQuesBean> hyMktUserQuesBeans) throws IOException, IllegalArgumentException, IllegalAccessException {

        HSSFWorkbook wb = new HSSFWorkbook();
        Sheet sheet = wb.createSheet();

        // 数据表头开始行
        CellStyle style = wb.createCellStyle();
        Font font = wb.createFont();
        font.setFontName("宋体");
        // 设置字体大小
        font.setFontHeightInPoints((short) 12);
        // 加粗
        font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
        // 设置背景色
        style.setFillForegroundColor(HSSFColor.LIME.index);
        style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
        // 让单元格居中
        style.setAlignment(HSSFCellStyle.SOLID_FOREGROUND);
        // 左右居中
        style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
        // 上下居中
        style.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);
        style.setWrapText(true);//设置自动换行
        style.setFont(font);

        // 添加表数据
        // 取出列表中问卷问题最多的对象做动态表头
        HyMktUserQuesBean problemMax = null;
        int maxSize = 0;
        for (int n = 0; n < hyMktUserQuesBeans.size(); n++) {
            HyMktUserQuesBean hyMktUserQuesBean = hyMktUserQuesBeans.get(n);
            // 记录最大问题个数
            if (hyMktUserQuesBean.getHyMktUserQuesAnswerBeans().size() > maxSize) {
                maxSize = hyMktUserQuesBean.getHyMktUserQuesAnswerBeans().size();
                problemMax = hyMktUserQuesBean;
            }
            int index = 0;
            // 写excel数据
            for (int i = 1; i < hyMktUserQuesBean.getHyMktUserQuesAnswerBeans().size(); i++) {
                // 第零行为表头行，不填充数据
                Row row = sheet.createRow(n + 1);
                // 用户名
                Cell firstCell = row.createCell(index);
                firstCell.setCellType(Cell.CELL_TYPE_STRING);
                firstCell.setCellValue(hyMktUserQuesBean.getWechatName());
                sheet.autoSizeColumn((short) index++);// 设置单元格自适应
                // 联系电话
                Cell secondCell = row.createCell(index);
                secondCell.setCellType(Cell.CELL_TYPE_STRING);
                secondCell.setCellValue(hyMktUserQuesBean.getTelephone());
                sheet.autoSizeColumn((short) index++);// 设置单元格自适应
                // 主题名称
                Cell thirdCell = row.createCell(index);
                thirdCell.setCellType(Cell.CELL_TYPE_STRING);
                thirdCell.setCellValue(hyMktUserQuesBean.getQuestionName());
                sheet.autoSizeColumn((short) index++);// 设置单元格自适应
                // 参与时间
                Cell forthCell = row.createCell(index);
                forthCell.setCellType(Cell.CELL_TYPE_STRING);
                forthCell.setCellValue(DateUtil.translateDate(hyMktUserQuesBean.getCreateTime().getTime()));
                sheet.autoSizeColumn((short) index++);// 设置单元格自适应
                // 动态表头
                List<HyMktUserQuesAnswerBean> hyMktUserQuesAnswerBeans = hyMktUserQuesBean.getHyMktUserQuesAnswerBeans();
                for(int k = 0; k < hyMktUserQuesAnswerBeans.size(); k++ ){
                    // 问题
                    Cell otherOneCell = row.createCell(index);
                    otherOneCell.setCellType(Cell.CELL_TYPE_STRING);
                    otherOneCell.setCellValue(hyMktUserQuesAnswerBeans.get(k).getProblemName());
                    sheet.autoSizeColumn((short) index++);// 设置单元格自适应
                    // 答案
                    Cell otherTwoCell = row.createCell(index);
                    otherTwoCell.setCellType(Cell.CELL_TYPE_STRING);
                    otherTwoCell.setCellValue(hyMktUserQuesAnswerBeans.get(k).getOptionName());
                    sheet.autoSizeColumn((short) index++);// 设置单元格自适应
                }
            }
        }
        //添加表头
        Row row = sheet.createRow(0);
        int index = 0;
        // 用户名
        Cell indexCell = row.createCell(index);
        indexCell.setCellType(Cell.CELL_TYPE_STRING);
        indexCell.setCellStyle(style);//设置表头样式
        indexCell.setCellValue("用户名");
        sheet.autoSizeColumn((short) index++);// 设置单元格自适应
        // 联系电话
        Cell indexCell2 = row.createCell(index);
        indexCell2.setCellType(Cell.CELL_TYPE_STRING);
        indexCell2.setCellStyle(style);//设置表头样式
        indexCell2.setCellValue("联系电话");
        sheet.autoSizeColumn((short) index++);// 设置单元格自适应
        // 主题名称
        Cell indexCell3 = row.createCell(index);
        indexCell3.setCellType(Cell.CELL_TYPE_STRING);
        indexCell3.setCellStyle(style);//设置表头样式
        indexCell3.setCellValue("主题名称");
        sheet.autoSizeColumn((short) index++);// 设置单元格自适应
        // 参与时间
        Cell indexCell4 = row.createCell(index);
        indexCell4.setCellType(Cell.CELL_TYPE_STRING);
        indexCell4.setCellStyle(style);//设置表头样式
        indexCell4.setCellValue("参与时间");
        sheet.autoSizeColumn((short) index++);// 设置单元格自适应
        for(int j = 0; j < problemMax.getHyMktUserQuesAnswerBeans().size(); j++ ){
            // 问题
            Cell otherOneCell = row.createCell(index);
            otherOneCell.setCellType(Cell.CELL_TYPE_STRING);
            otherOneCell.setCellStyle(style);//设置表头样式
            otherOneCell.setCellValue("问题" + (j + 1));
            sheet.autoSizeColumn((short) index++);// 设置单元格自适应
            // 答案
            Cell otherTwoCell = row.createCell(index);
            otherTwoCell.setCellType(Cell.CELL_TYPE_STRING);
            otherTwoCell.setCellStyle(style);//设置表头样式
            otherTwoCell.setCellValue("问题" + (j + 1) + "答案");
            sheet.autoSizeColumn((short) index++);// 设置单元格自适应
        }
        response.setContentType("application/vnd.ms-excel");
        response.setHeader("Content-disposition", "attachment;filename="" + new String(fileName.getBytes("gb2312"), "ISO8859-1") + ".xls" + """);
        OutputStream ouputStream = null;
        try {
            ouputStream = response.getOutputStream();
            wb.write(ouputStream);
        } finally {
            ouputStream.close();
        }
    }
}

导出结果：