用java寫MS Excel 檔案

以下是在POI官網的Quick Guide上摘錄的範例程式碼：

    InputStream inp = new FileInputStream("workbook.xls");    //InputStream inp = new FileInputStream("workbook.xlsx");    Workbook wb = WorkbookFactory.create(inp);    Sheet sheet = wb.getSheetAt(0);    Row row = sheet.getRow(2);    Cell cell = row.getCell(3);    if (cell == null)        cell = row.createCell(3);    cell.setCellType(Cell.CELL_TYPE_STRING);    cell.setCellValue("a test");    // Write the output to a file    FileOutputStream fileOut = new FileOutputStream("workbook.xls");    wb.write(fileOut);    fileOut.close();

1. 這段代碼最後是用以下這行來寫入檔案中的：  wb.write(fileOut);
2. 這段代碼的效率挺低的，我寫一個大一點的Excel，大概有二十萬個cell左右的檔案，竟然out of memory了。所以效率不高。