是否可以使用usermodel编写Excel文件并使用Apache POI中的eventmodel再次读取同一文件

Question

I tried writing to a new Excel file using the following code (uses usermodel)

    private static void writeToExecelFileUsingUserModel() throws InvalidFormatException, IOException {
    String[] header = {"","A","B","C", "D","E","F","G","I","J"};
    String[] dataSet = {"1","2","3","4","5","6","7","8","9","10"};
    HSSFWorkbook workbook = new HSSFWorkbook();   
    HSSFSheet sheet = (HSSFSheet) workbook.createSheet("testSheet");
    HSSFRow row = sheet.createRow(0);
    for(int i= 0; i <header.length; i++ ){
        HSSFCell cell = row.createCell(i);
        cell.setCellValue(header[i]);
    }
    HSSFRow row2 = sheet.createRow(1);
    for(int i= 0; i <dataSet.length; i++ ){
        HSSFCell cell = row2.createCell(i);
        cell.setCellValue(dataSet[i]);
    }

    try {
        FileOutputStream fos = new FileOutputStream("C:\\Test.xls");
        workbook.write(fos);
        System.out.println("write complete");
        fos.close();

    } catch (Exception e) {
        e.printStackTrace();
    }
}

Then, I used the same file and tried reading using eventmodel using the code below. It gave the error:

Exception in thread "main" org.apache.poi.openxml4j.exceptions.InvalidFormatException: Package should contain a content type part [M1.13] at org.apache.poi.openxml4j.opc.ZipPackage.getPartsImpl(ZipPackage.java:199) at org.apache.poi.openxml4j.opc.OPCPackage.getParts(OPCPackage.java:665) at org.apache.poi.openxml4j.opc.OPCPackage.open(OPCPackage.java:274) at com.benz.test.ReadFromExcel.readUsingEventModel(ReadFromExcel.java:34) at com.benz.test.ReadFromExcel.main(ReadFromExcel.java:24)

//code for reading from previously generated xls file using eventmodel

    private static void readUsingEventModel() throws IOException, OpenXML4JException {

    InputStream excelStream = null;
    OPCPackage pkg = null;
    System.out.println("reading using event model");
    try {
        FileInputStream myxls = new FileInputStream("C:\\Test.xls");
        pkg = OPCPackage.open(myxls);
        XSSFReader xssfReader = new XSSFReader(pkg);
        XSSFReader.SheetIterator iter = (XSSFReader.SheetIterator) xssfReader.getSheetsData();
        String sheetName = iter.getSheetName();
        System.out.println("sheet name is"+sheetName);
    } finally {
        if (excelStream != null) {
            excelStream.close();
        }
        if (pkg != null) {
            pkg.close();
        }
    }

}

Also the same scenario (ie writing using usermodel and reading using event model) works fine for xlsx file but does not work for xls files. Also I cannot use usermodel for reading as it is giving performance issues Any help would be greatly appreciated.Thanks

Answer 1

Your first set of code is all HSSF, which only works for .xls files:

HSSFWorkbook workbook = new HSSFWorkbook();  

Then, a little later, you're suddenly trying to use the XSSF code which only works for .xlsx files:

OPCPackage pkg = null;
XSSFReader xssfReader = new XSSFReader(pkg);

You have two choices. Firstly, you can change your initial code to be XSSF, using XSSFWorkbook and friends. If you generate your Excel file with XSSF as a .xlsx , then you can read it with XSSF code. Alternately, if you really want to be using HSSF / .xls for generation, and you want to use low-memory reading, then you need to use the HSSF Event API to do your read