点击导入excel,文件没上传，后台没反应

package org.imooc.util;

import org.apache.commons.fileupload.FileItem;

import java.io.File;

public class FileUtil {

   public static final String SAVE_PATH = "D:/java/Excel/upload/";
   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;
   }
}

package org.imooc.util;

import com.sun.deploy.net.HttpRequest;
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.UnsupportedEncodingException;
import java.util.List;

public class RequestUtil {
   public static ParamDto parseParam(HttpServletRequest request) throws UnsupportedEncodingException {
       ParamDto result = new ParamDto();
       ServletFileUpload upload = new ServletFileUpload(new DiskFileItemFactory());
       upload.setHeaderEncoding("UTF-8");
       try {
           List<FileItem> fileItems = upload.parseRequest(request);
           for (FileItem fileItem : fileItems) {
               if (fileItem.isFormField()) {
                        result.getParamMap().put(fileItem.getFieldName(),fileItem.getString("UTF-8"));
               } else {
                        result.getFileMap().put(fileItem.getFieldName(),fileItem);
               }
           }
       } catch (FileUploadException e) {
           e.printStackTrace();
       }
       return result;
   }
}

package org.imooc.servlet;


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.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.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

@WebServlet(name = "ImportExcelServlet")
public class ImportExcelServlet extends HttpServlet {
   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       if (ServletFileUpload.isMultipartContent(request)) {
           ParamDto dto = RequestUtil.parseParam(request);
           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);
           request.setAttribute("result", resultDto);
       }
       request.getRequestDispatcher("/WEB-INF/jsp/importExcelResult.jsp").forward(request,response);

   }


   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         this.doPost(request,response);
   }
}

package org.imooc.servlet;

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


public class ImportExcelInitServlet extends HttpServlet {
   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      request.getRequestDispatcher("/WEB-INF/jsp/importExcel.jsp").forward(request,response);
   }

   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       this.doPost(request,response);
   }
}