java apache poi 内存清空

Question

i have a code that goes something like this:

public class excelwriter {

    public static void main(String[] args) throws IOException {
        XSSFWorkbook workbook = new XSSFWorkbook();
        XSSFSheet sheet = workbook.createSheet("sheet1");

        for (int o = 1; o < 1000000; o++) {
            Row row = sheet.createRow(o);

            for (int i = 0; i < 100000; i++) {
                Cell cell = row.createCell(i); 
            }      
        }

        try (FileOutputStream outputStream = new FileOutputStream("C:/JavaBooks.xlsx")) {
            workbook.write(outputStream);
        }
    }
}

My problem is the heapspace error, to which i get sooner or later using this code, as the workbook object stores all the cells. How can i modify the code, that java after writing a row with all the cells, writes it to xlsx and throws the data away (or after 1000 rows if that makes it faster). Thank you

Answer 1

Just try replacing XSSFWorkbook with SXSSFWorkbook , then POI will write the intermediate data to temporary files and copy the result together in the call to write() .

See the description at http://poi.apache.org/spreadsheet/index.html and http://poi.apache.org/spreadsheet/how-to.html#sxssf