Internship: Upload method for writing excel sheet (import)

After the framework of the entire project is built,For programmers, you only need to start writing the business.比如一般的excel表的导入导出.such as personnelexcel表的导入导出.

以下是导入（把excelData upload realizes data interaction with the database）：

It needs to be based on database tables and excelThe table corresponds to the construction of the class,Similar to the following writing form

public class governmentsModel extends Model<governmentsModel> {
    



    private static long serialVersionUID=1L;


    @TableField(value = "id",type= IdType.AUTO)
    private Integer id;

    /** *...... */
    @Excel(name = "",width =25 )
    @TableField("name")
    @ApiModelProperty(value = "")
    private String name;

    /** *...... */
    @Excel(name = "",width =25 )
    @TableField("code")
    @ApiModelProperty(value = "")
    private String code;


    /** * */
    @TableField("type")
    private Integer type;

    /** *.... */
    @Excel(name = "",width =50 )
    @TableField("gb")
    @ApiModelProperty(value = "")
    private String gb;

    /** *..... */
    @Excel(name = "",width =50 )
    @TableField("category_code")
    @ApiModelProperty(value = "")
    private String category_code;

 
 ....................


}

@excelThe annotations are correspondingexcelThe fields in the table are easy to formexcel表.

After the class is built,Make the write upload method,如下：

/** * 上传人员excel * * @param file * @return */
    @RequestMapping(value = "/uploadExcel", method = RequestMethod.POST)
    public ResponseData uploadExcel(HttpServletRequest request, MultipartFile file) {
    
        ImportParams importParams = new ImportParams();
        importParams.setTitleRows(1);
        List<governmentsModel> result;
        try {
    
            result = ExcelImportUtil.importExcel(file.getInputStream(), governmentsModel.class, importParams);
        } catch (Exception e) {
    
            e.printStackTrace();
            throw new BusinessException(500, "表格导入错误!");
        }
        //保存员工信息
        if (ToolUtil.isEmpty(result)) {
    
            throw new BusinessException(BizExceptionEnum.EXCEL_EMPTY);
        }
        List<governmentsModel> errorList = employerService.importExcel(result);
        request.getSession().setAttribute("employerList", errorList);
        return new ResponseData<>(errorList.size() == 0);
    }

Read the code snippet line by line：
1、methodtaken naturallypost Because it is imported, it needs to be uploadedexcel表,ResponseDataThe class is for the convenience of unifying the data format of the front and back ends.
2、HttpServletRequest request, MultipartFile file 是上传excel表时 The necessary parameters for the method request意为请求——服务器请求对象 .MultipartFile——MultipartFile是SpringMVC提供简化上传操作的工具类.
在不使用框架之前,都是使用原生的HttpServletRequest来接收上传的数据,文件是以二进制流传递到后端的,然后需要我们自己转换为File类.使用了MultipartFile工具类之后,我们对文件上传的操作就简便许多了.
3、ImportParams Chinese translation into import parameters 配合 importParams.setTitleRows(1) The number of rows occupied by the header is by default1,Represents that the title occupies one line
4、用集合存储excel表数据,try catch异常捕获 通过ExcelImportUtil工具类 Call the import method——importExcel Pass in file input stream parameters、Use the reflection mechanism to obtain the corresponding base database table sumexcelThe number of rows occupied by the class parameters and headers corresponding to the table are built
5、After judging that it is not empty, the data is saved 至于errorListThe existence of is used to judge whether its field is in the businessnullbe exceptional among themerrorList.size() == 0返回的是布尔类型数据 为trueindicates that it was uploadedexcelThe table is complete and correct.

导出：

    @RequestMapping(value = "/download", method = RequestMethod.GET)
    public void download(HttpServletResponse response) {
    
        try {
    
            ExportParams exportParams = new ExportParams("标题：Indicate the intent");
            Workbook workbook = ExcelExportUtil.exportExcel(exportParams, governmentsModel.class, new ArrayList<>());
           
            String filename = "信息模板.xls";
            response.setContentType("application/force-download");
            response.setHeader("Content-disposition", "attachment;filename*=UTF-8''" + URLEncoder.encode(filename, "UTF-8"));
            OutputStream ouputStream = response.getOutputStream();
            workbook.write(ouputStream);
            ouputStream.flush();
            ouputStream.close();
        } catch (Exception e) {
    
            e.printStackTrace();
            throw new BusinessException(BizExceptionEnum.EXCEL_LOAD_WRONG);
        }
    }
}