使用POI读取大文件Excel

时间:2019-01-23
本文章向大家介绍使用POI读取大文件Excel,主要包括使用POI读取大文件Excel使用实例、应用技巧、基本知识点总结和需要注意事项,具有一定的参考价值,需要的朋友可以参考一下。

前言:前段时间,由于项目中有一个功能,导入大量的数据,整个Excel的容量大概有200M左右,用以前的方法读取很慢,甚至会内存溢出,所以后面改用另外一种方式(驱动模式),其实我也不是很懂,是借鉴了一个前辈的思路(https://www.cnblogs.com/swordfall/p/8298386.html),下面直接上码

 

1.引入jar包,POI的依赖包

<!-- poi office -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.16</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.16</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml-schemas</artifactId>
            <version>3.16</version>
        </dependency>

2.解析Excel2003的类ExcelXlsReader

public class ExcelXlsReader implements HSSFListener {

    private int minColums = -1;

    private POIFSFileSystem fs;

    /**
     * 总行数
     */
    private int totalRows=0;

    /**
     * 上一行row的序号
     */
    private int lastRowNumber;

    /**
     * 上一单元格的序号
     */
    private int lastColumnNumber;

    /**
     * 是否输出formula,还是它对应的值
     */
    private boolean outputFormulaValues = true;

    /**
     * 用于转换formulas
     */
    private EventWorkbookBuilder.SheetRecordCollectingListener workbookBuildingListener;

    //excel2003工作簿
    private HSSFWorkbook stubWorkbook;

    private SSTRecord sstRecord;

    private FormatTrackingHSSFListener formatListener;

    private final HSSFDataFormatter formatter = new HSSFDataFormatter();

    /**
     * 文件的绝对路径
     */
    private String filePath = "";

    //表索引
    private int sheetIndex = 0;

    private BoundSheetRecord[] orderedBSRs;

    @SuppressWarnings("unchecked")
    private ArrayList boundSheetRecords = new ArrayList();

    private int nextRow;

    private int nextColumn;

    private boolean outputNextStringRecord;

    //当前行
    private int curRow = 0;

    //存储一行记录所有单元格的容器
    private List<String> cellList = new ArrayList<String>();

    //第一个sheet列表
    private static List<List<String>> firstSheetList = new ArrayList<>();
    //第二个sheet列表
    private static List<List<String>> secondSheetList = new ArrayList<>();
    //第三个sheet列表
    private static List<List<String>> thirdSheetList = new ArrayList<>();

    private static Map<String,List<List<String>>> allListMap = new HashMap<>();


    /**
     * 判断整行是否为空行的标记
     */
    private boolean flag = false;

    @SuppressWarnings("unused")
    private String sheetName;

    /**
     * 遍历excel下所有的sheet
     *
     * @param file
     * @throws Exception
     */
    public Map<String,List<List<String>>> process(File file) throws Exception {
//        filePath = fileName;
        this.fs = new POIFSFileSystem(new FileInputStream(file));
        MissingRecordAwareHSSFListener listener = new MissingRecordAwareHSSFListener(this);
        formatListener = new FormatTrackingHSSFListener(listener);
        HSSFEventFactory factory = new HSSFEventFactory();
        HSSFRequest request = new HSSFRequest();
        if (outputFormulaValues) {
            request.addListenerForAllRecords(formatListener);
        } else {
            workbookBuildingListener = new EventWorkbookBuilder.SheetRecordCollectingListener(formatListener);
            request.addListenerForAllRecords(workbookBuildingListener);
        }
        factory.processWorkbookEvents(request, fs);

        allListMap.put("first",new ArrayList<>(firstSheetList));
        allListMap.put("second",new ArrayList<>(secondSheetList));
        allListMap.put("third",new ArrayList<>(thirdSheetList));
        firstSheetList.clear();
        secondSheetList.clear();
        thirdSheetList.clear();
        return allListMap;
    }

    /**
     * HSSFListener 监听方法,处理Record
     * 处理每个单元格
     * @param record
     */
    @SuppressWarnings("unchecked")
    public void processRecord(Record record) {
        int thisRow = -1;
        int thisColumn = -1;
        String thisStr = null;
        String value = null;
        switch (record.getSid()) {
            case BoundSheetRecord.sid:
                boundSheetRecords.add(record);
                break;
            case BOFRecord.sid: //开始处理每个sheet
                BOFRecord br = (BOFRecord) record;
                if (br.getType() == BOFRecord.TYPE_WORKSHEET) {
                    //如果有需要,则建立子工作簿
                    if (workbookBuildingListener != null && stubWorkbook == null) {
                        stubWorkbook = workbookBuildingListener.getStubHSSFWorkbook();
                    }

                    if (orderedBSRs == null) {
                        orderedBSRs = BoundSheetRecord.orderByBofPosition(boundSheetRecords);
                    }
                    sheetName = orderedBSRs[sheetIndex].getSheetname();
                    sheetIndex++;
                }
                break;
            case SSTRecord.sid:
                sstRecord = (SSTRecord) record;
                break;
            case BlankRecord.sid: //单元格为空白
                BlankRecord brec = (BlankRecord) record;
                thisRow = brec.getRow();
                thisColumn = brec.getColumn();
                thisStr = "";
                cellList.add(thisColumn, thisStr);
                break;
            case BoolErrRecord.sid: //单元格为布尔类型
                BoolErrRecord berec = (BoolErrRecord) record;
                thisRow = berec.getRow();
                thisColumn = berec.getColumn();
                thisStr = berec.getBooleanValue() + "";
                cellList.add(thisColumn, thisStr);
                checkRowIsNull(thisStr);  //如果里面某个单元格含有值,则标识该行不为空行
                break;
            case FormulaRecord.sid://单元格为公式类型
                FormulaRecord frec = (FormulaRecord) record;
                thisRow = frec.getRow();
                thisColumn = frec.getColumn();
                if (outputFormulaValues) {
                    if (Double.isNaN(frec.getValue())) {
                        outputNextStringRecord = true;
                        nextRow = frec.getRow();
                        nextColumn = frec.getColumn();
                    } else {
                        thisStr = '"' + HSSFFormulaParser.toFormulaString(stubWorkbook, frec.getParsedExpression()) + '"';
                    }
                } else {
                    thisStr = '"' + HSSFFormulaParser.toFormulaString(stubWorkbook, frec.getParsedExpression()) + '"';
                }
                cellList.add(thisColumn, thisStr);
                checkRowIsNull(thisStr);  //如果里面某个单元格含有值,则标识该行不为空行
                break;
            case StringRecord.sid: //单元格中公式的字符串
                if (outputNextStringRecord) {
                    StringRecord srec = (StringRecord) record;
                    thisStr = srec.getString();
                    thisRow = nextRow;
                    thisColumn = nextColumn;
                    outputNextStringRecord = false;
                }
                break;
            case LabelRecord.sid:
                LabelRecord lrec = (LabelRecord) record;
                curRow = thisRow = lrec.getRow();
                thisColumn = lrec.getColumn();
                value = lrec.getValue().trim();
                value = value.equals("") ? "" : value;
                cellList.add(thisColumn, value);
                checkRowIsNull(value);  //如果里面某个单元格含有值,则标识该行不为空行
                break;
            case LabelSSTRecord.sid: //单元格为字符串类型
                LabelSSTRecord lsrec = (LabelSSTRecord) record;
                curRow = thisRow = lsrec.getRow();
                thisColumn = lsrec.getColumn();
                if (sstRecord == null) {
                    cellList.add(thisColumn, "");
                } else {
                    value = sstRecord.getString(lsrec.getSSTIndex()).toString().trim();
                    value = value.equals("") ? "" : value;
                    cellList.add(thisColumn, value);
                    checkRowIsNull(value);  //如果里面某个单元格含有值,则标识该行不为空行
                }
                break;
            case NumberRecord.sid: //单元格为数字类型
                NumberRecord numrec = (NumberRecord) record;
                curRow = thisRow = numrec.getRow();
                thisColumn = numrec.getColumn();

                //第一种方式
                //value = formatListener.formatNumberDateCell(numrec).trim();//这个被写死,采用的m/d/yy h:mm格式,不符合要求

                //第二种方式,参照formatNumberDateCell里面的实现方法编写
                Double valueDouble=((NumberRecord)numrec).getValue();
                String formatString=formatListener.getFormatString(numrec);
                if (formatString.contains("m/d/yy")){
                    formatString="yyyy-MM-dd hh:mm:ss";
                }
                int formatIndex=formatListener.getFormatIndex(numrec);
                value=formatter.formatRawCellContents(valueDouble, formatIndex, formatString).trim();

                value = value.equals("") ? "" : value;
                //向容器加入列值
                cellList.add(thisColumn, value);
                checkRowIsNull(value);  //如果里面某个单元格含有值,则标识该行不为空行
                break;
            default:
                break;
        }

        //遇到新行的操作
        if (thisRow != -1 && thisRow != lastRowNumber) {
            lastColumnNumber = -1;
        }

        //空值的操作
        if (record instanceof MissingCellDummyRecord) {
            MissingCellDummyRecord mc = (MissingCellDummyRecord) record;
            curRow = thisRow = mc.getRow();
            thisColumn = mc.getColumn();
            cellList.add(thisColumn, "");
        }

        //更新行和列的值
        if (thisRow > -1)
            lastRowNumber = thisRow;
        if (thisColumn > -1)
            lastColumnNumber = thisColumn;

        //行结束时的操作
        if (record instanceof LastCellOfRowDummyRecord) {
            if (minColums > 0) {
                //列值重新置空
                if (lastColumnNumber == -1) {
                    lastColumnNumber = 0;
                }
            }
            lastColumnNumber = -1;

            if (flag&&curRow!=0) { //该行不为空行且该行不是第一行,发送(第一行为列名,不需要)
                switch(sheetIndex){
                    case 1 :
                        //第一个sheet
                        List<String> a = new ArrayList<>(cellList);
                        firstSheetList.add(a);
                        break;
                    case 2 :
                        //第二个sheet
                        List<String> b = new ArrayList<>(cellList);
                        secondSheetList.add(b);
                        break;
                    case 3 :
                        //第三个sheet
                        List<String> c =  new ArrayList<>(cellList);
                        thirdSheetList.add(c);
                        break;
                    default :
                        break;
                }
                totalRows++;
            }
            //清空容器
            cellList.clear();
            flag=false;
        }
    }

    /**
     * 如果里面某个单元格含有值,则标识该行不为空行
     * @param value
     */
    public void checkRowIsNull(String value){
        if (value != null && !"".equals(value)) {
            flag = true;
        }
    }

}

3.解析Excel2007的类ExcelXlsxReader

public class ExcelXlsxReader extends DefaultHandler {


    /**
     * 单元格中的数据可能的数据类型
     */
    enum CellDataType {
        BOOL, ERROR, FORMULA, INLINESTR, SSTINDEX, NUMBER, DATE, NULL
    }

    /**
     * 共享字符串表
     */
    private SharedStringsTable sst;

    /**
     * 上一次的索引值
     */
    private String lastIndex;

    /**
     * 文件的绝对路径
     */
    private String filePath = "";

    /**
     * 工作表索引
     */
    private int sheetIndex = 0;

    /**
     * sheet名
     */
    private String sheetName = "";

    /**
     * 总行数
     */
    private int totalRows=0;

    /**
     * 一行内cell集合
     */
    private static List<String> cellList = new ArrayList<>();

    //第一个sheet列表
    private static List<List<String>> firstSheetList = new ArrayList<>();
    //第二个sheet列表
    private static List<List<String>> secondSheetList = new ArrayList<>();
    //第三个sheet列表
    private static List<List<String>> thirdSheetList = new ArrayList<>();

    private static Map<String,List<List<String>>> allListMap = new HashMap<>();

    /**
     * 判断整行是否为空行的标记
     */
    private boolean flag = false;

    /**
     * 当前行
     */
    private int curRow = 1;

    /**
     * 当前列
     */
    private int curCol = 0;

    /**
     * T元素标识
     */
    private boolean isTElement;

    /**
     * 异常信息,如果为空则表示没有异常
     */
    private String exceptionMessage;

    /**
     * 单元格数据类型,默认为字符串类型
     */
    private CellDataType nextDataType = CellDataType.SSTINDEX;

    private final DataFormatter formatter = new DataFormatter();

    /**
     * 单元格日期格式的索引
     */
    private short formatIndex;

    /**
     * 日期格式字符串
     */
    private String formatString;

    //定义前一个元素和当前元素的位置,用来计算其中空的单元格数量,如A6和A8等
    private String preRef = null, ref = null;

    //定义该文档一行最大的单元格数,用来补全一行最后可能缺失的单元格
    private String maxRef = null;

    /**
     * 单元格
     */
    private StylesTable stylesTable;

    /**
     * 遍历工作簿中所有的电子表格
     * 并缓存在mySheetList中
     *
     * @param file
     * @throws Exception
     */
    public Map<String,List<List<String>>> process(File file) throws Exception {
//        filePath = filename;
        OPCPackage pkg = OPCPackage.open(file);
        XSSFReader xssfReader = new XSSFReader(pkg);
        stylesTable = xssfReader.getStylesTable();
        SharedStringsTable sst = xssfReader.getSharedStringsTable();
        XMLReader parser = XMLReaderFactory.createXMLReader("com.sun.org.apache.xerces.internal.parsers.SAXParser");
        this.sst = sst;
        parser.setContentHandler(this);
        XSSFReader.SheetIterator sheets = (XSSFReader.SheetIterator) xssfReader.getSheetsData();
        while (sheets.hasNext()) { //遍历sheet
            curRow = 1; //标记初始行为第一行
            sheetIndex++;
            InputStream sheet = sheets.next(); //sheets.next()和sheets.getSheetName()不能换位置,否则sheetName报错
            sheetName = sheets.getSheetName();
            InputSource sheetSource = new InputSource(sheet);
            parser.parse(sheetSource); //解析excel的每条记录,在这个过程中startElement()、characters()、endElement()这三个函数会依次执行
            sheet.close();
        }
        allListMap.put("first",new ArrayList<>(firstSheetList));
        allListMap.put("second",new ArrayList<>(secondSheetList));
        allListMap.put("third",new ArrayList<>(thirdSheetList));
        firstSheetList.clear();
        secondSheetList.clear();
        thirdSheetList.clear();
        return allListMap; //返回该excel文件的总行数,不包括首列和空行
    }

    /**
     * 第一个执行
     *
     * @param uri
     * @param localName
     * @param name
     * @param attributes
     * @throws SAXException
     */
    @Override
    public void startElement(String uri, String localName, String name, Attributes attributes) throws SAXException {
        //c => 单元格
        if ("c".equals(name)) {
            //前一个单元格的位置
            if (preRef == null) {
                preRef = attributes.getValue("r");
            } else {
                preRef = ref;
            }

            //当前单元格的位置
            ref = attributes.getValue("r");
            //设定单元格类型
            this.setNextDataType(attributes);
        }

        //当元素为t时
        if ("t".equals(name)) {
            isTElement = true;
        } else {
            isTElement = false;
        }

        //置空
        lastIndex = "";
    }

    /**
     * 第二个执行
     * 得到单元格对应的索引值或是内容值
     * 如果单元格类型是字符串、INLINESTR、数字、日期,lastIndex则是索引值
     * 如果单元格类型是布尔值、错误、公式,lastIndex则是内容值
     * @param ch
     * @param start
     * @param length
     * @throws SAXException
     */
    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        lastIndex += new String(ch, start, length);
    }

    /**
     * 第三个执行
     *
     * @param uri
     * @param localName
     * @param name
     * @throws SAXException
     */
    @Override
    public void endElement(String uri, String localName, String name) throws SAXException {

        //t元素也包含字符串
        if (isTElement) {//这个程序没经过
            //将单元格内容加入rowlist中,在这之前先去掉字符串前后的空白符
            String value = lastIndex.trim();
            cellList.add(curCol, value);
            curCol++;
            isTElement = false;
            //如果里面某个单元格含有值,则标识该行不为空行
            if (value != null && !"".equals(value)) {
                flag = true;
            }
        } else if ("v".equals(name)) {
            //v => 单元格的值,如果单元格是字符串,则v标签的值为该字符串在SST中的索引
            String value = this.getDataValue(lastIndex.trim(), "");//根据索引值获取对应的单元格值
            //补全单元格之间的空单元格
            if (!ref.equals(preRef)) {
                int len = countNullCell(ref, preRef);
                for (int i = 0; i < len; i++) {
                    cellList.add(curCol, "");
                    curCol++;
                }
            }
            cellList.add(curCol, value);
            curCol++;
            //如果里面某个单元格含有值,则标识该行不为空行
            if (value != null && !"".equals(value)) {
                flag = true;
            }
        } else {
            //如果标签名称为row,这说明已到行尾,调用optRows()方法
            if ("row".equals(name)) {
                //默认第一行为表头,以该行单元格数目为最大数目
                if (curRow == 1) {
                    maxRef = ref;
                }
                //补全一行尾部可能缺失的单元格
                if (maxRef != null) {
                    int len = countNullCell(maxRef, ref);
                    for (int i = 0; i <= len; i++) {
                        cellList.add(curCol, "");
                        curCol++;
                    }
                }

                if (flag&&curRow!=1){ //该行不为空行且该行不是第一行,则发送(第一行为列名,不需要)
                    switch(sheetIndex){
                        case 1 :
                            //第一个sheet
                            List<String> a = new ArrayList<>(cellList);
                            firstSheetList.add(a);
                            break;
                        case 2 :
                            //第二个sheet
                            List<String> b = new ArrayList<>(cellList);
                            secondSheetList.add(b);
                            break;
                        case 3 :
                            //第三个sheet
                            List<String> c =  new ArrayList<>(cellList);
                            thirdSheetList.add(c);
                            break;
                        default :
                            break;
                    }
//                    ExcelReaderUtil.sendRows(filePath, sheetName, sheetIndex, curRow, cellList);
                    totalRows++;
                }

                cellList.clear();
                curRow++;
                curCol = 0;
                preRef = null;
                ref = null;
                flag=false;
            }
        }
    }

    /**
     * 处理数据类型
     *
     * @param attributes
     */
    public void setNextDataType(Attributes attributes) {
        nextDataType = CellDataType.NUMBER; //cellType为空,则表示该单元格类型为数字
        formatIndex = -1;
        formatString = null;
        String cellType = attributes.getValue("t"); //单元格类型
        String cellStyleStr = attributes.getValue("s"); //
        String columnData = attributes.getValue("r"); //获取单元格的位置,如A1,B1

        if ("b".equals(cellType)) { //处理布尔值
            nextDataType = CellDataType.BOOL;
        } else if ("e".equals(cellType)) {  //处理错误
            nextDataType = CellDataType.ERROR;
        } else if ("inlineStr".equals(cellType)) {
            nextDataType = CellDataType.INLINESTR;
        } else if ("s".equals(cellType)) { //处理字符串
            nextDataType = CellDataType.SSTINDEX;
        } else if ("str".equals(cellType)) {
            nextDataType = CellDataType.FORMULA;
        }

        if (cellStyleStr != null) { //处理日期
            int styleIndex = Integer.parseInt(cellStyleStr);
            XSSFCellStyle style = stylesTable.getStyleAt(styleIndex);
            formatIndex = style.getDataFormat();
            formatString = style.getDataFormatString();

            if (formatString.contains("m/d/yy")) {
                nextDataType = CellDataType.DATE;
                formatString = "yyyy-MM-dd hh:mm:ss";
            }

            if (formatString == null) {
                nextDataType = CellDataType.NULL;
                formatString = BuiltinFormats.getBuiltinFormat(formatIndex);
            }
        }
    }

    /**
     * 对解析出来的数据进行类型处理
     * @param value   单元格的值,
     *                value代表解析:BOOL的为0或1, ERROR的为内容值,FORMULA的为内容值,INLINESTR的为索引值需转换为内容值,
     *                SSTINDEX的为索引值需转换为内容值, NUMBER为内容值,DATE为内容值
     * @param thisStr 一个空字符串
     * @return
     */
    @SuppressWarnings("deprecation")
    public String getDataValue(String value, String thisStr) {
        switch (nextDataType) {
            // 这几个的顺序不能随便交换,交换了很可能会导致数据错误
            case BOOL: //布尔值
                char first = value.charAt(0);
                thisStr = first == '0' ? "FALSE" : "TRUE";
                break;
            case ERROR: //错误
                thisStr = "\"ERROR:" + value.toString() + '"';
                break;
            case FORMULA: //公式
                thisStr = '"' + value.toString() + '"';
                break;
            case INLINESTR:
                XSSFRichTextString rtsi = new XSSFRichTextString(value.toString());
                thisStr = rtsi.toString();
                rtsi = null;
                break;
            case SSTINDEX: //字符串
                String sstIndex = value.toString();
                try {
                    int idx = Integer.parseInt(sstIndex);
                    XSSFRichTextString rtss = new XSSFRichTextString(sst.getEntryAt(idx));//根据idx索引值获取内容值
                    thisStr = rtss.toString();
                    rtss = null;
                } catch (NumberFormatException ex) {
                    thisStr = value.toString();
                }
                break;
            case NUMBER: //数字
                if (formatString != null) {
                    thisStr = formatter.formatRawCellContents(Double.parseDouble(value), formatIndex, formatString).trim();
                } else {
                    thisStr = value;
                }
                thisStr = thisStr.replace("_", "").trim();
                break;
            case DATE: //日期
                thisStr = formatter.formatRawCellContents(Double.parseDouble(value), formatIndex, formatString);
                // 对日期字符串作特殊处理,去掉T
                thisStr = thisStr.replace("T", " ");
                break;
            default:
                thisStr = " ";
                break;
        }
        return thisStr;
    }

    public int countNullCell(String ref, String preRef) {
        //excel2007最大行数是1048576,最大列数是16384,最后一列列名是XFD
        String xfd = ref.replaceAll("\\d+", "");
        String xfd_1 = preRef.replaceAll("\\d+", "");

        xfd = fillChar(xfd, 3, '@', true);
        xfd_1 = fillChar(xfd_1, 3, '@', true);

        char[] letter = xfd.toCharArray();
        char[] letter_1 = xfd_1.toCharArray();
        int res = (letter[0] - letter_1[0]) * 26 * 26 + (letter[1] - letter_1[1]) * 26 + (letter[2] - letter_1[2]);
        return res - 1;
    }

    public String fillChar(String str, int len, char let, boolean isPre) {
        int len_1 = str.length();
        if (len_1 < len) {
            if (isPre) {
                for (int i = 0; i < (len - len_1); i++) {
                    str = let + str;
                }
            } else {
                for (int i = 0; i < (len - len_1); i++) {
                    str = str + let;
                }
            }
        }
        return str;
    }

    /**
     * @return the exceptionMessage
     */
    public String getExceptionMessage() {
        return exceptionMessage;
    }

}

4.Excel辅助工具类ExcelReaderUtil,我把这些代码做了一下处理,现在可以直接一次性读取3个sheet的内容,直接调用readExcel()方法即可

public class ExcelReaderUtil {

    //excel2003扩展名
    public static final String EXCEL03_EXTENSION = ".xls";
    //excel2007扩展名
    public static final String EXCEL07_EXTENSION = ".xlsx";



    /**
     * @Author cjw
     * @Description 获取整个Excel的内容
     * @Date 10:18 2019/1/23
     * @Param [file]
     * @return 目前最多只读取三个sheet,可以自行扩展
     **/
    public static ImportExcelData readExcel(MultipartFile file) throws Exception {
        // 获取文件名
        if (file == null) {
            return null;
        }
        String fileName = file.getOriginalFilename();
        // 获取文件后缀
        String prefix = fileName.substring(fileName.lastIndexOf("."));
        if (!prefix.toLowerCase().contains("xls") && !prefix.toLowerCase().contains("xlsx")) {
            throw new Exception("文件格式错误,fileName的扩展名只能是xls或xlsx。");
        }
        // 防止生成的临时文件重复
        final File excelFile = File.createTempFile(System.currentTimeMillis() + "", prefix);
        file.transferTo(excelFile);

        Map<String, List<List<String>>> result = new HashMap<>();
        if (fileName.endsWith(EXCEL03_EXTENSION)) { //处理excel2003文件
            ExcelXlsReader excelXls = new ExcelXlsReader();
            result = excelXls.process(excelFile);
        } else if (fileName.endsWith(EXCEL07_EXTENSION)) {//处理excel2007文件
            ExcelXlsxReader excelXlsxReader = new ExcelXlsxReader();
            result = excelXlsxReader.process(excelFile);
        } else {
            throw new Exception("文件格式错误,fileName的扩展名只能是xls或xlsx。");
        }
        ImportExcelData data = new ImportExcelData();
        for (Map.Entry<String, List<List<String>>> entry : result.entrySet()) {
            if ("first".equals(entry.getKey())) {
                data.setFirstSheetList(result.get(entry.getKey()));
            }
            if ("second".equals(entry.getKey())) {
                data.setSecondSheetList(result.get(entry.getKey()));
            }
            if ("third".equals(entry.getKey())) {
                data.setThirdSheetList(result.get(entry.getKey()));
            }
        }
        //删除临时转换的文件
        if (excelFile.exists()) {
            excelFile.delete();
        }
        return data;
    }


}

4.1sheet内容封装类

@Data
public class ImportExcelData {

    //第一个sheet
    private List<List<String>> firstSheetList;

    //第二个sheet
    private List<List<String>> secondSheetList;

    //第三个sheet
    private List<List<String>> thirdSheetList;
}

5.测试

上传了一个200M左右的Excel,可以看到,整个解析时间大概是一分多钟