老是，文件解析失败，但保存成功，代码也没写错呀

package com.cl.service;

import com.cl.data.Course;
import com.cl.dto.ImportExcelParamDto;
import com.cl.dto.ImportExcelResultDto;
import com.cl.util.FileUtil;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;

public class ExcelService {

    public CourseService imp(ImportExcelParamDto paramDto) throws IOException {
        //有来有回，对导入的一个结果进行预处理，封装一个复杂对象，对出错信息进行一个处理
      //  ImportExcelResultDto result=new ImportExcelResultDto();
        CourseService result=new CourseService();
       // result.setTitle(paramDto.getTitle());
        List<Course> courseList=new ArrayList<>();
        result.setCs(courseList);
        String fileName = null;
        try {
            fileName = FileUtil.save(paramDto.getExcel(), FileUtil.SAVE_PATH);
        } catch (Exception e) {
            e.printStackTrace();
            result.setMsg("上传文件保存失败！");
        }
        if (fileName != null) {
            Workbook workbook = null;
            try {
                //另外一种需求就是，只需要获取到文件的输入流，而不要保存文件
                //方法，new File(paramDto.getExcel().getInputStream())即可
                workbook = WorkbookFactory.create(new File(FileUtil.SAVE_PATH+fileName));
                Sheet sheet = workbook.getSheetAt(0);
                //sheet-row-cell
                int rowNum = sheet.getLastRowNum();
                for (int i = 0; i <= rowNum; i++) {
                    Course course=new Course();
                    Row row = sheet.getRow(i);
                    course.setCourseId(row.getCell(0).getStringCellValue());
                    course.setCourseName(row.getCell(1).getStringCellValue());
                    course.setCourseType(row.getCell(2).getStringCellValue());
                    course.setDescription(row.getCell(3).getStringCellValue());
                    course.setCourseTime((float)row.getCell(4).getNumericCellValue());
                    course.setUsername(row.getCell(5).getStringCellValue());
                    courseList.add(course);
                    System.out.println(row.getCell(0).getStringCellValue());
                    System.out.println(row.getCell(1).getStringCellValue());
                    System.out.println(row.getCell(2).getStringCellValue());
                    System.out.println(row.getCell(3).getStringCellValue());
                    System.out.println((float)row.getCell(4).getNumericCellValue());
                    System.out.println(row.getCell(5).getStringCellValue());
                }
            }catch (Exception e){
                e.printStackTrace();
                result.setMsg("文件解析失败");
            }finally {
                if(workbook != null) {
                    try {
                        //释放wookBook所占用的资源
                        workbook.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
        return result;

    }
  //导出课程相关信息
    public  Workbook export(boolean flag){
        Workbook workbook;
        //这个地方有分为03和07版excel
        if(flag){
            //03
            workbook=new XSSFWorkbook();
        }else{
            //07
            workbook=new HSSFWorkbook();
        }
        //思路：sheet->row->cell
        Sheet sheet = workbook.createSheet("my sheet");
        //创建一个二维数据来模拟数据
        List<List<String>> content = this.getContent();
        for(int i=0;i<content.size();i++) {
            Row row = sheet.createRow(i);
            List<String> rowData=content.get(i);
            for (int j = 0; j < rowData.size(); j++) {
                row.createCell(j).setCellValue(rowData.get(j));
                System.out.println(content.get(i).get(j));
            }
        }
        return workbook;
    }
    //获取用户提交的数据
    private   List<List<String>> getContent(){

        return null;
    }
}