Java 实现excel大批量导出

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

@Test
    public 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;
        }
    }