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实现excel大数据量导出

导出Excel时，如果数据量较大，全部查询出来list,然后写入Workboook，会出现内存异常异常，建议使用SXSSFWorkbook，然后设置setCompressTempFiles属性为true

@Testpublic void testBigExcel(){try {long startTime = System.currentTimeMillis();final int NUM_OF_ROWS = 1300000;final int NUM_OF_COLUMNS = 21;SXSSFWorkbook wb = null;try {wb = new SXSSFWorkbook();//压缩临时文件，很重要，否则磁盘很快就会被写满wb.setCompressTempFiles(true);Sheet sh =null;int sheetNum=1;int rowNum = 0;for (int num = 0; num < NUM_OF_ROWS; num++) {if (num % 1000000 == 0) {sh = wb.createSheet("Sheet " + sheetNum);rowNum = 0;sheetNum++;}else{rowNum++;}org.apache.poi.ss.usermodel.Row row = sh.createRow(rowNum);for (int cellNum = 0; cellNum < NUM_OF_COLUMNS; cellNum++) {Cell cell = row.createCell(cellNum);cell.setCellValue(Math.random());}}FileOutputStream out = new FileOutputStream("d:/Maruko.xlsx");wb.write(out);out.close();} catch (Exception ex) {ex.printStackTrace();} finally {if (wb != null) {wb.dispose();// 删除临时文件，很重要，否则磁盘可能会被写满}}long endTime = System.currentTimeMillis();System.out.println("花费时间为：" + (endTime - startTime));} catch (Exception e) {e.printStackTrace();throw e;}}