一种excel多线程并发写sheet的方案

一、背景

有一次项目的需求要求导出excel，并且将不同的数据分别写到不同的sheet中。

二、方案概述

首先一开始使用easyexcel去导出excel，结果发现导出时间需要3秒左右。于是想着能不能缩短excel导出时间，于是第一次尝试使用异步线程去查询数据库，却发现接口的时间并没有明显缩短，于是自己就开始排查耗时的操作，于是发现是写sheet的时候是串行执行，并且每个写sheet的时间并不短，尤其在sheet比较多的时候，会导致导出的时间比较长。于是，想着能不能使用异步线程并发去写sheet，但是，使用的时候报错。后来去找报错的原因，是因为easyexcel并不支持并发写。于是，我就转战POI。尝试是否能够并发写入多个sheet。

使用easyexcel写入多个sheet

        try {
            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(EXCEL, "UTF-8").replaceAll("\\+", "%20");
            response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");
            AtomicInteger atomicInteger = new AtomicInteger(0);
            ExcelWriter build = EasyExcel.write(response.getOutputStream(),VirtualInstanceDataPoint.class).build();
            list.stream().map(i -> CompletableFuture.supplyAsync(() -> {
                        return service.list();
                    }, executor)).collect(Collectors.toList()).stream()
                    .map(CompletableFuture::join).collect(Collectors.toList()).forEach(r->{
                        int andIncrement = atomicInteger.getAndIncrement();
                        WriteSheet build1 = EasyExcel.writerSheet(andIncrement, r.get(0).getDevice() + andIncrement).build();
                        build.write(r, build1);
                    });
            build.finish();
            response.flushBuffer();
        } catch (Exception e) {
            // 重置response
            response.reset();
            response.setContentType("application/json");
            response.setCharacterEncoding("utf-8");
            response.getWriter().println(JSON.toJSONString(R.error().message(e.getMessage()).code(20007)));
}

并发写入多个sheet会报

org.apache.poi.openxml4j.exceptions.PartAlreadyExistsException: A part with the name '/xl/worksheets/sheet1.xml' already exists : Packages shall not contain equivalent part names and package implementers shall neither create nor recognize packages with equivalent part names. [M1.12]

POI写入多个sheet

    String[] EXPORT_HEADER = {"head1","head2"};
    @GetMapping("export3")
    @ApiOperation(value = "excel导出信息")
    @SneakyThrows
    public void export3(HttpServletResponse response) {
        OutputStream outputStream = response.getOutputStream();
        response.reset();
        response.setContentType("application/vnd.ms-excel");
        response.setHeader("Content-disposition", "attachment;filename=template.xls");
        AtomicInteger atomicInteger = new AtomicInteger();
        HSSFWorkbook workbook = new HSSFWorkbook();
        Font font = workbook.createFont();
        font.setBold(true);
        HSSFCellStyle cellStyle = workbook.createCellStyle();
        cellStyle.setAlignment(HorizontalAlignment.CENTER);
        cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
        cellStyle.setFont(font);
        List<IndexData> indexDatas = new ArrayList<>();
        indexDatas.add(new IndexData("1",1.1));
        indexDatas.add(new IndexData("2",2.2));
        indexDatas.add(new IndexData("3",3.3));
        for (IndexData indexData : indexDatas) {
            HSSFSheet sheet = workbook.createSheet(indexData.getStr());
            HSSFRow row = sheet.createRow(0);
            // 创建表头
            for (int i = 0; i < EXPORT_HEADER.length; i++) {
                HSSFCell cell = row.createCell(i);
                cell.setCellValue(EXPORT_HEADER[i]);
                cell.setCellStyle(cellStyle);
            }
            row = sheet.createRow(1);
            row.createCell(0).setCellValue(indexData.getStr());
            row.createCell(1).setCellValue(indexData.getDoubleData());
        }

        workbook.write(outputStream);
        outputStream.flush();
        outputStream.close();
    }
    static  class IndexData {
        public IndexData(String string, Double doubleData) {
            this.str = string;
            this.doubleData = doubleData;
        }

        public String getStr() {
            return str;
        }

        public Double getDoubleData() {
            return doubleData;
        }

        private String str;

        private Double doubleData;
    }

POI多线程写多个sheet

    String[] EXPORT_HEADER = {"head1","head2"};
    @GetMapping("export3")
    @ApiOperation(value = "excel导出")
    @SneakyThrows
    public void export3(HttpServletResponse response) {
        OutputStream outputStream = response.getOutputStream();
        response.reset();
        response.setContentType("application/vnd.ms-excel");
        response.setHeader("Content-disposition", "attachment;filename=template.xls");
        AtomicInteger atomicInteger = new AtomicInteger();
        HSSFWorkbook workbook = new HSSFWorkbook();
        Font font = workbook.createFont();
        font.setBold(true);
        HSSFCellStyle cellStyle = workbook.createCellStyle();
        cellStyle.setAlignment(HorizontalAlignment.CENTER);
        cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
        cellStyle.setFont(font);
        List<IndexData> indexDatas = new ArrayList<>();
        indexDatas.add(new IndexData("1",1.1));
        indexDatas.add(new IndexData("2",2.2));
        indexDatas.add(new IndexData("3",3.3));
        indexDatas.stream().map(data ->CompletableFuture.runAsync(() ->{
            HSSFSheet sheet = workbook.createSheet(data.getStr());
            HSSFRow row = sheet.createRow(0);
            // 创建表头
            for (int i = 0; i < EXPORT_HEADER.length; i++) {
                HSSFCell cell = row.createCell(i);
                cell.setCellValue(EXPORT_HEADER[i]);
                cell.setCellStyle(cellStyle);
            }
            row = sheet.createRow(1);
            row.createCell(0).setCellValue(data.getStr());
            row.createCell(1).setCellValue(data.getDoubleData());
        })).collect(Collectors.toList()).stream().map(CompletableFuture::join).collect(Collectors.toList());
        workbook.write(outputStream);
        outputStream.flush();
        outputStream.close();
    }
    static  class IndexData {
        public IndexData(String string, Double doubleData) {
            this.str = string;
            this.doubleData = doubleData;
        }

        public String getStr() {
            return str;
        }

        public Double getDoubleData() {
            return doubleData;
        }

        private String str;

        private Double doubleData;
    }

但是有时候会报错

java.lang.IllegalArgumentException: calculated end index (2576) is out of allowable range (2564..2569)

是因为在子线程中创建sheet产生并发。

一个解决方案是主线程预先创建sheet

另一个方案是为创建sheet的操作加锁

    @GetMapping("export1")
    @ApiOperation(value = "excel导出信息")
    @SneakyThrows
    public void export2(HttpServletResponse response) {
        OutputStream outputStream = response.getOutputStream();
        response.reset();
        response.setContentType("application/vnd.ms-excel");
        response.setHeader("Content-disposition", "attachment;filename=template.xls");
        AtomicInteger atomicInteger = new AtomicInteger();
        HSSFWorkbook workbook = new HSSFWorkbook();
        Font font = workbook.createFont();
        font.setBold(true);
        HSSFCellStyle cellStyle = workbook.createCellStyle();
        cellStyle.setAlignment(HorizontalAlignment.CENTER);
        cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
        cellStyle.setFont(font);
        list.stream().map(instanceId -> CompletableFuture.runAsync(() -> {
                    List<> collect =  service.list();
                    HSSFSheet sheet = workbook.createSheet(collect.get(0).getDevice()+ atomicInteger.getAndIncrement());
                    HSSFRow row = sheet.createRow(0);
                    // 创建表头
                    for (int i = 0; i < EXPORT_HEADER.length; i++) {
                        HSSFCell cell = row.createCell(i);
                        cell.setCellValue(EXPORT_HEADER[i]);
                        cell.setCellStyle(cellStyle);
                    }
                    for (int i = 0; i < collect.size(); i++) {
                        row = sheet.createRow(i + 1);
                        row.createCell(0).setCellValue(collect.get(i).getInstanceId());
                        row.createCell(1).setCellValue(collect.get(i).getDevice());
                        row.createCell(2).setCellValue(collect.get(i).getDataId());
                        row.createCell(3).setCellValue(collect.get(i).getDataName());
                    }
                }, executor)).collect(Collectors.toList()).stream()
                .map(CompletableFuture::join).collect(Collectors.toList());
        workbook.write(outputStream);
        outputStream.flush();
        outputStream.close();
        
    }

以下使用加锁方式

    String[] EXPORT_HEADER = {"head1","head2"};
    @GetMapping("export3")
    @ApiOperation(value = "excel导出信息")
    @SneakyThrows
    public void export3(HttpServletResponse response) {
        OutputStream outputStream = response.getOutputStream();
        response.reset();
        response.setContentType("application/vnd.ms-excel");
        response.setHeader("Content-disposition", "attachment;filename=template.xls");
        AtomicInteger atomicInteger = new AtomicInteger();
        HSSFWorkbook workbook = new HSSFWorkbook();
        Font font = workbook.createFont();
        font.setBold(true);
        HSSFCellStyle cellStyle = workbook.createCellStyle();
        cellStyle.setAlignment(HorizontalAlignment.CENTER);
        cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
        cellStyle.setFont(font);
        List<IndexData> indexDatas = new ArrayList<>();
        indexDatas.add(new IndexData("1",1.1));
        indexDatas.add(new IndexData("2",2.2));
        indexDatas.add(new IndexData("3",3.3));
        indexDatas.stream().map(data ->CompletableFuture.runAsync(() ->{
            HSSFSheet sheet = getSheet(data, workbook);
            HSSFRow row = sheet.createRow(0);
            // 创建表头
            for (int i = 0; i < EXPORT_HEADER.length; i++) {
                HSSFCell cell = row.createCell(i);
                cell.setCellValue(EXPORT_HEADER[i]);
                cell.setCellStyle(cellStyle);
            }
            row = sheet.createRow(1);
            row.createCell(0).setCellValue(data.getStr());
            row.createCell(1).setCellValue(data.getDoubleData());
        })).collect(Collectors.toList()).stream().map(CompletableFuture::join).collect(Collectors.toList());
        workbook.write(outputStream);
        outputStream.flush();
        outputStream.close();
    }

    @org.jetbrains.annotations.NotNull
    private synchronized static HSSFSheet getSheet(IndexData data, HSSFWorkbook workbook) {
        HSSFSheet sheet = workbook.createSheet(data.getStr());
        return sheet;
    }

但是这种方式还是会有一些并发带来的错误。

java.lang.NullPointerException: null
   at org.apache.poi.hssf.record.SSTSerializer.serialize(SSTSerializer.java:70)
   at org.apache.poi.hssf.record.SSTRecord.serialize(SSTRecord.java:279)
   at org.apache.poi.hssf.record.cont.ContinuableRecord.getRecordSize(ContinuableRecord.java:60)
   at org.apache.poi.hssf.model.InternalWorkbook.getSize(InternalWorkbook.java:1072)
   at org.apache.poi.hssf.usermodel.HSSFWorkbook.getBytes(HSSFWorkbook.java:1474)
   at org.apache.poi.hssf.usermodel.HSSFWorkbook.write(HSSFWorkbook.java:1386)
   at org.apache.poi.hssf.usermodel.HSSFWorkbook.write(HSSFWorkbook.java:1374)

但是在本机实测100个线程10个循环出错的个数在20-30之间

我们可以捕获这些错误使用do while循环，当出错的时候可以清空状态再次重试。