使用Apache poi Excel实现Excel导出数据的工具类
1、添加maven依赖

<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi</artifactId>
    <version>3.16</version>
</dependency>
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi-ooxml</artifactId>
    <version>3.16</version>
</dependency>

2、Excel导出工具类，支持07版Excel导出格式为“xlsx”

package com.linksfield.topup.utils;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.xssf.streaming.SXSSFSheet;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;

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

/**
 * @author: songgt
 * @date: 2019-12-19 10:11
 */
public class ExcelUtil {

    /**
     * 根据resultList生成Excel,但是只是生成xlsx为后缀格式的Excel，只能Excel 2007以上的版本可以打开
     * 可生成多个工作表，每个工作表最多60000行数据，可以将缓存中的数据先存放到硬盘里再清理缓存
     * @param response
     * @param fileName
     * @param nameArray
     * @param rtnList
     * @throws Exception
     */
    public static void exportExcel2007(HttpServletResponse response,
                                       String fileName, String[] nameArray, String[] keyArray,
                                       List<Map<String, Object>> rtnList) {
        int maxRow = 60000;
        try{
            OutputStream os = response.getOutputStream();
            response.setHeader("Content-disposition", "attachment; filename="
                    + new String(fileName.getBytes("gb2312"), "ISO8859-1") + ".xlsx");
            response.setContentType("application/msexcel");
            // 内存中缓存记录行数
            int rowAccess = 100;
            SXSSFWorkbook wb = new SXSSFWorkbook(rowAccess);
            int listSize = rtnList.size();
            // 总工作表
            int sheetNum = listSize / 60000 + 1;
            // 总列数
            int cellTotal = nameArray.length;
            // 数据list的取值下标
            int listNum = 0;
            for (int i = 0; i < sheetNum; i++) {
                Sheet sh = wb.createSheet(fileName + "sheet" + String.valueOf(i));
                // 每个SHEET有60000ROW
                for (int rowNum = 0; rowNum <= maxRow; rowNum++) {
                    Row row = sh.createRow(rowNum);
                    // 每行有cellTotal个CELL
                    if (rowNum == 0){
                        for (int cellNum = 0; cellNum < cellTotal; cellNum++) {
                            Cell cell = row.createCell(cellNum);
                            cell.setCellValue(nameArray[cellNum]);
                        }
                    }else {
                        // 判断是否已取完数据
                        if (listNum < listSize) {
                            Map<String, Object> map = rtnList.get(listNum);
                            listNum++;
                            for (int cellNum = 0; cellNum < cellTotal; cellNum++) {
                                Cell cell = row.createCell(cellNum);
                                String key = keyArray[cellNum];
                                String value = map.get(key) != null ? map.get(key).toString() : "";
                                cell.setCellValue(value);
                            }
                        } else {
                            break;
                        }
                    }
                    // 每当行数达到设置的值就刷新数据到硬盘,以清理内存
                    if (rowNum % rowAccess == 0) {
                        ((SXSSFSheet) sh).flushRows();
                    }
                }
            }
            wb.write(os);
            os.close();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

3、编写测试Controller

/**
 * @author: songgt
 * @date: 2019-12-19 10:20
 */
@RestController
public class ExcelExportController {

    @ApiOperation(value = "试用用户-导出excel")
    @GetMapping(path = "/exportTrialUserList")
    public void exportTrialUserList(HttpServletResponse response,@RequestHeader(name = "x-access-token", required = false) String token){
        Map<String,Object> map = new HashMap<String, Object>();
        map.put("a",1);
        map.put("b",2);
        map.put("c",3);
        map.put("d",4);
        List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
        list.add(map);
        String[] names = {"字段1","字段2","字段3","字段4"};
        String[] keys = map.keySet().toArray(new String[map.size()]);
        String fileName = "测试Excel";
        ExcelUtil.exportExcel2007(response,fileName,names,keys,list);
    }
}