Apache POI import export excel file

Introduce dependencies

<dependency>
	<groupId>org.apache.poi</groupId>
	<artifactId>poi</artifactId>
	<version>3.17</version>
</dependency>
<dependency>
	<groupId>org.apache.poi</groupId>
	<artifactId>poi-ooxml</artifactId>
	<version>3.17</version>
</dependency>

Upload Excel

Upload files Dom

  <div class="layui-body" style="margin: 1%">
      <div class="layui-upload-drag" id="fileUpload">
          <i class="layui-icon">&#xe67c;</i>
          <p> Click upload , Or drag the file here </p>
      </div>
  </div>

js

 layui.use(['upload', 'element','table'], function() {
    
        var $ = layui.jquery,upload = layui.upload,table = layui.table;
            upload.render({
    
            elem: '#fileUpload',
            url: '/file/import',
            accept:'file',
            done: function(res){
    
                console.log(res.msg);
            }
        });
}

Java Code

    
    @RequestMapping("/import")
    @ResponseBody
    public ResponseResult importExcel(@RequestParam("file")MultipartFile file) throws Exception{
    
        ResponseResult res=new ResponseResult();
        // 1. The file cannot be empty 
        if (file.isEmpty()){
    
            res.setMessage(" The file is empty , Can't upload ");
        }
        // 2.POI obtain Excel Parsing data 
        HSSFWorkbook wb=new HSSFWorkbook(file.getInputStream());
        HSSFSheet sheet=wb.getSheetAt(0);

        // 3. Define a set , Receive data from files 
        List<City> dataList=new ArrayList();

        HSSFRow row=null;


        // 4. Parsing data , Put it in the collection 
        for (int i = 0; i < sheet.getPhysicalNumberOfRows(); i++) {
    
            // Define the entity 
            City data=new City();

            // Data for each line 
            row=sheet.getRow(i);

            // Parsing data 
            data.setCity(row.getCell(0).getStringCellValue());
            data.setValue((int)row.getCell(1).getNumericCellValue());
            dataList.add(data);
             //3. Insert database 
            cityService.addCity(dataList);
        }
        res.setCode("200");
        res.setMessage(" Upload successful ");
        res.setObj(dataList);
        return res;
    }

export Excel

export Dom

  <button type="button" class="layui-btn layui-btn-sm latui-btn-radius" lay-submit="" lay-filter="doExport">
      <i class="layui-icon layui-icon-file"> export Excel</i>
  </button>

js

        form.on('submit(doExport)',function () {
    
            window.location.href="/export"
        })

Java Code

    @RequestMapping("/export")
    @ResponseBody
    public void exportExcel(HttpServletResponse response) throws Exception {
    
        //1. Query the database ,
        List<City> datalist = cityService.findAll();
        //2. establish Excel object , Encapsulated data 
        response.setCharacterEncoding("UTF-8");
        //2.1  establish Excel object 
        HSSFWorkbook wb=new HSSFWorkbook();
        //2.2  establish sheet object 
        HSSFSheet sheet = wb.createSheet(" Epidemic data in China Sheet1");
        //2.3  Create header 
        HSSFRow hssfRow=sheet.createRow(0);
        hssfRow.createCell(0).setCellValue(" The city name ");
        hssfRow.createCell(1).setCellValue(" Number of confirmed cases ");
        //3. Traversal data 
        for(City data:datalist){
    
            HSSFRow dataRow=sheet.createRow(sheet.getLastRowNum()+1);
            dataRow.createCell(0).setCellValue(data.getName());
            dataRow.createCell(1).setCellValue(data.getValue());
        }
        //4. Create output stream , Output file to browser 
        OutputStream os=null;
        //4.1  Set up Excel File name 
        response.setContentType("application/octet-stream;charset=utf-8");
        response.setHeader( "Content-Disposition", "attachment;filename=" + new String( " Epidemic data sheet ".getBytes("gb2312"), "ISO8859-1" ));
        //4.2  The output file 
        os= response.getOutputStream();
        wb.write(os);
        os.flush();
        //5. Close output stream 
        os.close();
    }