POI的使用

POI指的是java中的excel不同版本的导入导出。

POI组件的详细介绍文档：

https://www.cnblogs.com/huajiezh/p/5467821.html

1...依赖

.xls对应 HSSFWorkbook book = new HSSFWorkbook(io);

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

.xlsx对应XSSFWorkbook book = new XSSFWorkbook(io)

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

2...controller

package com.test.domi.controller;


import com.test.domi.annotation.IsFileWanner;
import org.apache.poi.xssf.usermodel.*;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletResponse;
import javax.validation.ConstraintViolationException;
import java.io.OutputStream;

@Validated
@RestController
@RequestMapping("/excel")
public class ExcelController {

    @GetMapping("/download")
    public void download(HttpServletResponse response) throws Exception{
        XSSFWorkbook workbook = new XSSFWorkbook();
        //获取文档信息，并配置
//        DocumentSummaryInformation dsi = workbook.getDocumentSummaryInformation();
        //创建一个Excel表单,参数为sheet的名字
        XSSFSheet sheet = workbook.createSheet("课调答卷表");
        //创建表头
        setTitle(workbook, sheet);
        //新增数据行，并且设置单元格数据
        int rowNum = 1;
        for (int i=0;i<2;i++) {
            XSSFRow row = sheet.createRow(rowNum);
            row.createCell(0).setCellValue(1);
            row.createCell(1).setCellValue(2);
            row.createCell(2).setCellValue(3);
            row.createCell(3).setCellValue(4);
            rowNum++;
        }
        String fileName = "survey-answer";
        response.setCharacterEncoding("UTF-8");
        response.setHeader("Content-Disposition", "attachment;filename="+ fileName + ".xlsx");
        response.setContentType("application/vnd.ms-excel;charset=utf-8");
        //清空response
        //response.reset();
        //设置response的Header
        //OutputStream os = new BufferedOutputStream(response.getOutputStream());

        OutputStream os = response.getOutputStream();

        //将excel写入到输出流中
        workbook.write(os);
        //finally关闭流
        os.flush();
        os.close();

    }

    /***
     * 设置表头
     * @param workbook
     * @param sheet
     */
    private void setTitle(XSSFWorkbook workbook, XSSFSheet sheet){
        XSSFRow row = sheet.createRow(0);
        //设置列宽，setColumnWidth的第二个参数要乘以256，这个参数的单位是1/256个字符宽度
        sheet.setColumnWidth(0, 10*256);
        sheet.setColumnWidth(1, 20*256);
        sheet.setColumnWidth(2, 20*256);
        sheet.setColumnWidth(3, 100*256);

        //设置为居中加粗
        XSSFCellStyle style = workbook.createCellStyle();
        XSSFFont font = workbook.createFont();
        font.setBold(true);
        style.setFont(font);

        XSSFCell cell;
        cell = row.createCell(0);
        cell.setCellValue("序号");
        cell.setCellStyle(style);

        cell = row.createCell(1);
        cell.setCellValue("单选");
        cell.setCellStyle(style);

        cell = row.createCell(2);
        cell.setCellValue("多选");
        cell.setCellStyle(style);

        cell = row.createCell(3);
        cell.setCellValue("简答");
        cell.setCellStyle(style);
    }

    /***
     * 上传Excel
     * @param file
     */
    @ExceptionHandler(ConstraintViolationException.class)
    @PostMapping("/importEmp")
    public Boolean importEmp(@RequestParam("file") @IsFileWanner(fileTypes = {"xls","xlsx"},fileSize = 113L) MultipartFile file) throws Exception{
        //附件类型的注解校验封装
        //判断文件的后缀，用响应的解析类解析
        if (file==null) {
            return false;
        }
        try {
            XSSFWorkbook workbook = new XSSFWorkbook(file.getInputStream());
            int sheets = workbook.getNumberOfSheets();
            for (int i = 0; i < sheets; i++) {
                XSSFSheet sheetAt = workbook.getSheetAt(i);
                int physicalNumberOfRows = sheetAt.getPhysicalNumberOfRows();
                System.out.println("nihao");
            }

        } catch (Exception e) {
            return false;
        }
        return true;
    }
}