ams-backend/src/main/java/com/ichaoj/ams/common/util/PoiUtils.java

package com.ichaoj.ams.common.util;

import cn.hutool.core.date.DateUtil;
import cn.hutool.core.io.IoUtil;
import cn.hutool.poi.excel.ExcelUtil;
import cn.hutool.poi.excel.ExcelWriter;
import com.ichaoj.ams.response.statistics.SheetDTO;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.util.IOUtils;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
import java.util.List;

/**
 * POI相关操作
 * @author cjwen
 */
public class PoiUtils {
    /**
     * 导出多个 Sheet 页
     * @param response 响应
     * @param sheetList 页数据
     * @param fileName 文件名
     */
    public static void exportExcel(HttpServletResponse response, List<SheetDTO> sheetList, String fileName) {
        ExcelWriter bigWriter = ExcelUtil.getBigWriter();
        // 重命名第一个Sheet的名称，不然会默认多出一个Sheet1的页
        bigWriter.renameSheet(0, sheetList.get(0).getSheetName());
        for (SheetDTO sheet : sheetList) {
            // 指定要写出的 Sheet 页
            bigWriter.setSheet(sheet.getSheetName());
            List<Integer> columnWidth = sheet.getColumnWidth();
            if (columnWidth == null || columnWidth.size() != sheet.getFieldAndAlias().size()) {
                // 设置默认宽度
                for (int i = 0; i < sheet.getFieldAndAlias().size(); i++) {
                    bigWriter.setColumnWidth(i, 25);
                }
            } else {
                // 设置自定义宽度
                for (int i = 0; i < columnWidth.size(); i++) {
                    bigWriter.setColumnWidth(i, columnWidth.get(i));
                }
            }
            // 设置字段和别名
            bigWriter.setHeaderAlias(sheet.getFieldAndAlias());
            // 设置只导出有别名的字段
            bigWriter.setOnlyAlias(true);
            // 设置默认行高
            bigWriter.setDefaultRowHeight(18);
            // 设置冻结行
            bigWriter.setFreezePane(1);
            // 一次性写出内容，使用默认样式，强制输出标题
            bigWriter.write(sheet.getCollection(), true);
            // 设置所有列为自动宽度，不考虑合并单元格
        }

        ServletOutputStream out = null;
        try {
            //response为HttpServletResponse对象
            response.setContentType("application/vnd.ms-excel;charset=utf-8");
            response.setHeader("Content-Disposition",
                    "attachment;filename=" +
                            URLEncoder.encode(fileName + DateUtil.today() + ".xlsx", "UTF-8"));
            out = response.getOutputStream();
            bigWriter.flush(out, true);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭writer，释放内存
            bigWriter.close();
        }
        //此处记得关闭输出Servlet流
        IoUtil.close(out);
    }
}