InternalSheet serialize?

[董青 <dq...@gmail.com>]

I read a topic from another site showing this function.
The code is written under POI 3.1. But some classes have another names in
POI 3.7. I found Workbook changed to InternalWorkbook and Sheet changed to
InternalSheet. But some function in the classes is no longer exist.
Now I meet this problem that I can preSerialize() the InternalSheet, But I
can't serialize it. The functions I didn't find are figured out below.
I need some help. Thank you.

   1. static byte[] getBytes(Workbook workbook, Sheet[] sheets) {
   2.         int nSheets = sheets.length;
   3.
   4.         for(int i = 0; i < nSheets; i++){
   5.             sheets[i].preSerialize();
   6.         }
   7.
   8.         int totalsize = workbook.getSize();
   9.
   10.         int[] estimatedSheetSizes = new int[nSheets];
   11.         for(int k = 0; k < nSheets; k++){
   12.             workbook.setSheetBof(k, totalsize);
   13.             int sheetSize = sheets[k].getSize();     ------------I
   can't find this getSize()
   14.             estimatedSheetSizes[k] = sheetSize;
   15.             totalsize += sheetSize;
   16.         }
   17.
   18.         byte[] retval = new byte[totalsize];
   19.         int pos = workbook.serialize(0, retval);     ------------AND
   I can't find this serialize() either.
   20.
   21.         for(int k = 0; k < nSheets; k++){
   22.             int
    serializedSize = sheets[k].serialize(pos, retval);
   23.             if(serializedSize != estimatedSheetSizes[k]){
   24.                 throw new IllegalStateException(
   "Actual serialized sheet size (" + serializedSize
   25.                         + ") differs from pre-calculated size ("
    + estimatedSheetSizes[k] + ") for sheet (" + k
   26.                         + ")");
   27.             }
   28.             pos += serializedSize;
   29.         }
   30.         return retval;
   31.     }