关于EasyExcel的上传和导出

1.导出。easyExcel与传统的poi相比，速度更快，数据量大也能快速导出。因为底层封装的方法是一行一行导出，比所有数据一起导出会快。

@Autowired
FestivalService festivalService;
@RequestMapping(value = "/exportData.ctrl")
public void exportData(HttpServletResponse response,@RequestBody Map<String, Object> param) throws IOException {
    log.getLogger("test_c").info("testexport({},{})", "开始",param);
    response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
    response.setCharacterEncoding("utf-8");
    // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系
    String fileName = URLEncoder.encode("年节数据导出", "UTF-8").replaceAll("\\+", "%20");
    response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");
    List<NewYearData> sublist = new ArrayList<NewYearData>();
    sublist=festivalService.selectDataExport(param);
    EasyExcel.write(response.getOutputStream(), NewYearData.class).sheet("模板").doWrite(sublist);
    log.getLogger("test_c").info("exportEnd({})", "结束");
}
创建一个实体类

public class NewYearBackend  {
    @ExcelProperty("用户手机号")
    private String mobileNumber;
    @ExcelProperty("分享时间")
    private String shareAt;
    @ExcelProperty("拉新俱乐部会员数")
    private int newShare ;
    @ExcelProperty("拉新游戏用户数")
    private int gameShare;
    @ExcelProperty("获得碎片总数")
    private int frageCount ;
    @ExcelProperty("分享总次数")
    private int shareTimes ;
    @ExcelProperty("会员编号")
    private int accountId ;
    @ExcelProperty("是否完成问卷")
    private String ifDone;
    @ExcelProperty("游戏获得碎片数")
    private int gameCount ;
    @ExcelProperty("分享获得碎片数")
    private int shareCount ;
    @ExcelProperty("官方链接碎片数")
    private int officeCount ;
    @ExcelProperty("问卷获得碎片数")
    private int questionCount;
    @ExcelProperty("剩余碎片数")
    private int saveCount ;}
2.导入 第一步创建一个实体类，第二步，创建一个Listener implements ReadListener<T> 第三步，调用通用方法。

public class DemoListener<T> implements ReadListener<T> {

    public static final int BATCH_COUNT = 3000;
    /**
     * Temporary storage of data
     */
    private List<T> cachedData = ListUtils.newArrayListWithExpectedSize(BATCH_COUNT);
    /**
     * consumer
     */
    private final Consumer<List<T>> consumer;

    public DemoListener(Consumer<List<T>> consumer) {
        this.consumer = consumer;
    }
    @Override
    public void invoke(T data, AnalysisContext context) {
        cachedData.add(data);
        if (cachedData.size() >= BATCH_COUNT) {
            consumer.accept(cachedData);
            // 存储完成清理 list
            cachedData = ListUtils.newArrayListWithExpectedSize(BATCH_COUNT);
        }
    }

    @Override
    public void doAfterAllAnalysed(AnalysisContext context) {
        consumer.accept(cachedData);
    }
}

public class DemoData {
    @ExcelProperty("名字")
    private String string;

    @DateTimeFormat("yyyy-MM-dd")
    @ExcelProperty("日期")
    private String date;

    @ExcelProperty("数字")
    private Double doubleData;

@RequestMapping(value = "/import.ctrl", method = RequestMethod.POST,  produces = "application/json")
public String importExcel( @RequestParam(required = false) MultipartFile file) throws IOException {
    EasyExcel.read(file.getInputStream(), DemoData.class, new DemoListener<DemoData>(dataList -> {
        for (DemoData demoData : dataList) {
            log.getLogger("test_c").info("excelData:({})", demoData);
        }
    })).sheet().doRead();
    log.getLogger("test_c").info("importExcelEnd({})", "结束");
    return "success";
}