导入功能实现失败....

Excelservice.java:
package org.imooc.service;

import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.usermodel.WorkbookFactory;
import org.imooc.dto.ImportExcelParamDto;
import org.imooc.dto.ImportExcelResultDto;
import org.imooc.entity.Student;
import org.imooc.util.FileUtil;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class ExcelService {

    public ImportExcelResultDto imp(ImportExcelParamDto dto){
        ImportExcelResultDto result=new ImportExcelResultDto();
        result.setTitle(dto.getTitle());
        List<Student> studentlist=new ArrayList<>();
        result.setStudentList(studentlist);
        String filename=FileUtil.save(dto.getExcel(),FileUtil.savepath());
        if(filename!=null){
            Workbook workbook = null;
            try {
                 workbook=WorkbookFactory.create(new File(FileUtil.savepath()+ filename));
                Sheet sheet=workbook.getSheetAt(0);
                int rowNum=sheet.getLastRowNum();
                    for (int i = 1; i <=rowNum ; i++) {
                    Row row=sheet.getRow(i);
                    Student student=new Student();
                    studentlist.add(student);
                    student.setName(row.getCell(0).getStringCellValue());
                    student.setAge((int)row.getCell(1).getNumericCellValue());
                    student.setTime(row.getCell(2).getDateCellValue());
                }
            } catch (Exception e) {
                result.setMsg("解析Excel失败！");
                e.printStackTrace();
            }
            finally {
                if(workbook != null){
                    try {
                        workbook.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }

            }
        }
        return result;
    }
}


importexcelservlet.java:
package org.imooc.servlet;

import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.imooc.dto.ImportExcelParamDto;
import org.imooc.dto.ImportExcelResultDto;
import org.imooc.dto.ParamDto;
import org.imooc.service.ExcelService;
import org.imooc.util.RequestUtil;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ImportExcelServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        if(ServletFileUpload.isMultipartContent(req)){
           ParamDto dto=RequestUtil.parseParam(req);
           ImportExcelParamDto paramdto=new ImportExcelParamDto();
           paramdto.setTitle(dto.getParamMap().get("title"));
           paramdto.setExcel(dto.getFileMap().get("excel"));
           ExcelService service=new ExcelService();
           ImportExcelResultDto resultDto=service.imp(paramdto);
           req.setAttribute("result",resultDto);
        }
        else{

        }
        req.getRequestDispatcher("/WEB-INF/jsp/importExcelResult.jsp").forward(req,resp);
    }
}


requestutil:
package org.imooc.util;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.imooc.dto.ParamDto;

import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.util.List;
public class RequestUtil {

    /**
     * 从request流中解析参数与上传的文件
     * @param request
     */
    public static ParamDto parseParam(HttpServletRequest request) {
        ParamDto result = new ParamDto();
        ServletFileUpload upload = new ServletFileUpload(new DiskFileItemFactory());
        upload.setHeaderEncoding("UTF-8");
        try {
            List<FileItem> fileItemList = upload.parseRequest(request);
            for(FileItem fileItem : fileItemList) {
                if(fileItem.isFormField()) {
                    result.getParamMap().put(fileItem.getFieldName(),fileItem.getString("UTF-8"));
                } else {
                    result.getFileMap().put(fileItem.getFieldName(),fileItem);

                }

            }
        } catch (FileUploadException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }
}



fileutil；
package org.imooc.util;

import org.apache.commons.fileupload.FileItem;

import java.io.File;

public class FileUtil {
    //上传文件的保存路径
    public static final String savepath(){
        return "d:/upload/";
    }
    //保存上传的文件
    public static String save(FileItem fileItem, String path){
        String fileName=System.currentTimeMillis()+"_"+fileItem.getName();

        try {
            fileItem.write(new File(path+fileName));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return fileName;

    }
}
这四个文件行嘛，功能实现主要是靠这四个吧

建议同学将导入的代码贴上来，方便我们帮你查看问题。贴代码时选择我要回答，选择代码语言。祝：学习愉快~