spring boot 将数据导出Excel 并实现下载功能

Controller层：

 @RequestMapping(value="/admin/download",produces = {"application/vnd.ms-excel;charset=UTF-8"})
    public ResponseEntity<byte[]> download(HttpSession session, HttpServletResponse response){

            List<CompetitionSignUp> upList=competitionSignUpDao.findAll();
            for (int i=0;i<upList.size();i++){
                //给报名表中的student 属性赋值
                upList.get(i).setStudent(studentDao.findOne(upList.get(i).getStudentId()));
            }
            String fileName="学生成绩统计表";
            List<Map<String,Object>> list=exportExcel.createExcelRecord(upList);
            String columnNames[]={"学号","姓名","性别","专业","班级","报名时间"};//列名
            String keys[]    =     {"studentNumber","studentName","studentSex","studentSpecialy","studentClass","time"};//map中的key
            ByteArrayOutputStream os = new ByteArrayOutputStream();
            try {
                ExcelUtils.createWorkBook(list,keys,columnNames).write(os);
            } catch (IOException e) {
                e.printStackTrace();
            }
            byte[] content = os.toByteArray();
            HttpHeaders httpHeaders = new HttpHeaders();
            httpHeaders.add("Content-Disposition", "attachment;filename="+ new String((fileName + ".xlsx").getBytes()));
            ResponseEntity<byte[]> responseEntity = new ResponseEntity<byte[]>(content,httpHeaders,HttpStatus.OK);
        return responseEntity;
    }
}

servicec 层

package com.haue.jobonline.service.impl;

import com.haue.jobonline.dao.CompetitionSignUpDao;
import com.haue.jobonline.entity.CompetitionSignUp;
import com.haue.jobonline.service.SignUpService;
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.xssf.usermodel.*;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author 赵鑫
 * @Time: 2018/7/22
 * @Email:[email protected]
 */
@Service
public class ExportExcel {
    @Resource
    private CompetitionSignUpDao competitionSignUpDao;
    public List<Map<String, Object>> createExcelRecord(List<CompetitionSignUp> competitionSignUps) {
        List<Map<String, Object>> listmap = new ArrayList<Map<String, Object>>();
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("sheetName", "sheet1");
        listmap.add(map);
        for (int j = 0; j < competitionSignUps.size(); j++) {
            CompetitionSignUp competitionSignUp=competitionSignUps.get(j);
            Map<String, Object> mapValue = new HashMap<String, Object>();
//            String keys[]    =     {"studentNumber","studentName","studentSex","studentSpecialy","studentClass","time"};//map中的key
            mapValue.put("studentNumber", competitionSignUp.getStudent().getStudentSchoolNum());
            mapValue.put("studentName",competitionSignUp.getStudent().getStudentName());
            mapValue.put("studentSex",competitionSignUp.getStudent().getStudentSex());
            mapValue.put("studentSpecialy",competitionSignUp.getStudent().getStudentSpecialty());
            mapValue.put("studentClass",competitionSignUp.getStudent().getStudentClass());
            mapValue.put("time",competitionSignUp.getSignTime());
            listmap.add(mapValue);
        }
        return listmap;
    }


}

工具类

package com.haue.jobonline.utils;

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.util.List;
import java.util.Map;

/**
 * @author 赵鑫
 * @Time: 2018/7/22
 * @Email:[email protected]
 */
public class ExcelUtils {
    /**
     * 创建excel文档，
     *  list 数据
     * @param keys list中map的key数组集合
     * @param columnNames excel的列名
     * */
    public static Workbook createWorkBook(List<Map<String, Object>> list, String []keys, String columnNames[]) {
        // 创建excel工作簿
        Workbook wb = new XSSFWorkbook();
        // 创建第一个sheet（页），并命名
        Sheet sheet = wb.createSheet(list.get(0).get("sheetName").toString());
        // 手动设置列宽。第一个参数表示要为第几列设；，第二个参数表示列的宽度，n为列高的像素数。
        for(int i=0;i<keys.length;i++){
            sheet.setColumnWidth((short) i, (short) (35.7 * 200));
        }

        // 创建第一行
        Row row = sheet.createRow((short) 0);

        // 创建两种单元格格式
        CellStyle cs = wb.createCellStyle();
        CellStyle cs2 = wb.createCellStyle();

        // 创建两种字体
        Font f = wb.createFont();
        Font f2 = wb.createFont();

        // 创建第一种字体样式（用于列名）
        f.setFontHeightInPoints((short) 10);
        f.setColor(IndexedColors.BLACK.getIndex());
        f.setBoldweight(Font.BOLDWEIGHT_BOLD);

        // 创建第二种字体样式（用于值）
        f2.setFontHeightInPoints((short) 10);
        f2.setColor(IndexedColors.BLACK.getIndex());

//        Font f3=wb.createFont();
//        f3.setFontHeightInPoints((short) 10);
//        f3.setColor(IndexedColors.RED.getIndex());

        // 设置第一种单元格的样式（用于列名）
        cs.setFont(f);
        cs.setBorderLeft(CellStyle.BORDER_THIN);
        cs.setBorderRight(CellStyle.BORDER_THIN);
        cs.setBorderTop(CellStyle.BORDER_THIN);
        cs.setBorderBottom(CellStyle.BORDER_THIN);
        cs.setAlignment(CellStyle.ALIGN_CENTER);
        // 设置第二种单元格的样式（用于值）
        cs2.setFont(f2);
        cs2.setBorderLeft(CellStyle.BORDER_THIN);
        cs2.setBorderRight(CellStyle.BORDER_THIN);
        cs2.setBorderTop(CellStyle.BORDER_THIN);
        cs2.setBorderBottom(CellStyle.BORDER_THIN);
        cs2.setAlignment(CellStyle.ALIGN_CENTER);
        //设置列名
        for(int i=0;i<columnNames.length;i++){
            Cell cell = row.createCell(i);
            cell.setCellValue(columnNames[i]);
            cell.setCellStyle(cs);
        }
        //设置每行每列的值
        for (short i = 1; i < list.size(); i++) {
            // Row 行,Cell 方格 , Row 和 Cell 都是从0开始计数的
            // 创建一行，在页sheet上
            Row row1 = sheet.createRow((short) i);
            // 在row行上创建一个方格
            for(short j=0;j<keys.length;j++){
                Cell cell = row1.createCell(j);
                cell.setCellValue(list.get(i).get(keys[j]) == null?" ": list.get(i).get(keys[j]).toString());
                cell.setCellStyle(cs2);
            }
        }
        return wb;
    }
}