EasyExcel导出数据量大导致内存溢出

一次性读入过多数据，如果内存不够大就会导致内存溢出，所以将数据分批处理，最后在EasyExcel导出的时候再汇总导出。至于接口耗时问题，就需要根据实际调整批次的最大数量。

java 复制代码

/**
	 * 全量导出工艺工时
	 * @param response 请求信息
	 */
	@Override
	public void exportEngineeringStandardWorkTime(HttpServletResponse response) {
		
		//获取需要导出的数据
		List<MoonStandardWorkTimeExportVO> moonStandardWorkTimeExportVOList = this.baseMapper.selectEngineeringStandardWorkTime();

		// 分批写入数据
		int batchSize = 100000; // 每批写入的数据量
		List<List<MoonStandardWorkTimeExportVO>> batchedData = splitIntoBatches(moonStandardWorkTimeExportVOList, batchSize);


		//导出数据
		try {
			String fileName = "设备工艺工时信息" + LocalDate.now();
			fileName = URLEncoder.encode(fileName, "UTF-8").replaceAll("\\+", "%20");
			response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");

			WriteCellStyle contentWriteCellStyle = new WriteCellStyle();
			contentWriteCellStyle.setHorizontalAlignment(HorizontalAlignment.CENTER);

			EasyExcel.write(response.getOutputStream(), MoonStandardWorkTimeExportVO.class)
				.registerWriteHandler(new LongestMatchColumnWidthStyleStrategy())
				.registerWriteHandler(new HorizontalCellStyleStrategy(new WriteCellStyle(), contentWriteCellStyle))
				.sheet("设备工艺工时信息")
				.doWrite(batchedData.stream().flatMap(List::stream).collect(Collectors.toList()));


		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}

	/**
	 * 将数据列表分割成多个小批量
	 *
	 * @param dataList 数据列表
	 * @param size     每个批次的大小
	 * @return 分割后的数据列表
	 */
	private List<List<MoonStandardWorkTimeExportVO>> splitIntoBatches(List<MoonStandardWorkTimeExportVO> dataList, int size) {
		List<List<MoonStandardWorkTimeExportVO>> batches = new ArrayList<>();
		for (int i = 0; i < dataList.size(); i += size) {
			batches.add(dataList.subList(i, Math.min(i + size, dataList.size())));
		}
		return batches;
	}