Java EasyExcel工具类 Java应用EasyExcel工具类

 private CommonService commonService;
    public void importExcel(MultipartFile file) throws IOException {
    // HEAD_ROW_NUMBER为Excel中的头部行数, 这里的关于ImportExcelListener的构造方法中HEAD_ROW_NUMBER参数可以根据需要决定传或者不传
        EasyExcel.read(file.getInputStream(), StudentVo.class, new ImportExcelListener<StudentVo>(HEAD_ROW_NUMBER, commonService)).sheet().headRowNumber(HEAD_ROW_NUMBER).doRead();
    }

public class ImportExcelListener<T> extends AnalysisEventListener<T> {
        /**
         * 每隔BATCH_COUNT条存储数据库 然后清理list ，方便内存回收
         */
        private static final int BATCH_COUNT = 500;
        private int headRowNum;
        private CommonService commonService;
        private List<T> list = new ArrayList<>();

        public ImportExcelListener(int headRowNumber, CommonService commonService) {
            this.headRowNum = headRowNumber;
            this.commonService = commonService;
        }

        /**
         * 这个每一条数据解析都会来调用
         */
        @Override
        public void invoke(T data, AnalysisContext context) {
            // 这里也可以将data转为对应实体, 然后做一些参数校验
            Integer rowNum = context.readRowHolder().getRowIndex();
           log.info("当前解析的数据为第{}行", rowNum);
          
            list.add(data);
            // 批量保存, 防止一次性数据过多, 内存溢出
            if (list.size() >= BATCH_COUNT) {
                // 保存
                commonService.save(list);
                list.clear();
            }
        }


        // 在解析之后, 也要记得再判断是否为空, 不为空要保存一下
        @Override
        public void doAfterAllAnalysed(AnalysisContext context) {
            if (CollectionUtils.isEmpty(list)) {
                return;
            }
            commonService.save(list);
            list.clear();
        }
    }

List<Object> data = null;
        try {
            data = EasyExcelFactory.read(file.getInputStream()).sheet().doReadSync();
        } catch (IOException e) {
            log.error("读取失败", e);
            throw new BusinessException("读取失败");
        }
        // 保存操作
        // ...

public void test() throws FileNotFoundException {
        File file = new File("E:\\work-grandview\\测试.xlsx");
        // 创建writerBuilder对象，自动调整列宽
        ExcelWriter excelWriter = EasyExcel.write(new FileOutputStream(file))
                .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())
                .autoCloseStream(Boolean.TRUE)
                .build();

        //  List<List<?>>类型, 二维数据, 表示第几行第几列, 设置表头内容
        List<List<String>> titleList = new ArrayList<>();
        titleList.add(Arrays.asList("名称", "key", "value"));
        int sheetNum = 0;
        WriteSheet writeSheet = EasyExcel.writerSheet(sheetNum,"导出数据").build();
        excelWriter.write(titleList, writeSheet);

        // 生成导出内容;
        List<List<Object>> content = new ArrayList<>();
        // 10行3列
        for (int i = 0; i < 10; i++) {
            List<Object> dataList = new ArrayList<>();
            for (int j = 0; j < 3; j++) {
                dataList.add(j);
            }
            content.add(dataList);
        }


        // 写入文件
        excelWriter.write(content, writeSheet);
        // 关闭文件流
        excelWriter.finish();
    }

@Data
 public class VO {
        @ExcelProperty(value = "姓名", index = 0)
        int name;
        @ExcelProperty(value = "key", index = 1)
        int key;
        @ExcelProperty(value = "value", index = 2)
        int value;
    }

@Test
    public void test() throws FileNotFoundException {
        File file = new File("E:\\work-grandview\\测试.xlsx");
        // 创建writerBuilder对象，自动调整列宽
        ExcelWriter excelWriter = EasyExcel.write(new FileOutputStream(file))
                .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())
                .autoCloseStream(Boolean.TRUE)
                .build();

        // 生成导出内容;
        List<VO> content = new ArrayList<>();
        // 10行3列
        for (int i = 0; i < 10; i++) {
            VO vo = new VO();
            vo.setKey(i);
            vo.setName(i);
            vo.setValue(i);
           content.add(vo);
        }
		// 创建sheet, 设置0号表, 实际运用中可能得创建多张, 可以遍历数据, 每满足n条就创建i号sheet表
        WriteSheet writeSheet = EasyExcel.writerSheet(0,"导出数据").build();
        // 设置表头
        writeSheet.setClazz(content.get(0).getClass());
        // 写入文件
        excelWriter.write(content, writeSheet);
        excelWriter.finish();

    }