To split a PDF document into multiple pages.

PDFDoc doc = new PDFDoc(filename);
int page_num = doc.getPageCount();
for (int i=1; i<=page_num; ++i)
{
  PDFDoc new_doc = new PDFDoc();
  new_doc.insertPages(0, doc, i, i, PDFDoc.InsertBookmarkMode.NONE, null);
  new_doc.save(output_filename + "_split_page_" + i + ".pdf", SDFDoc.SaveMode.LINEARIZED, null);
  new_doc.close();
}

Merge, Copy, Delete, and Rearrange PDF Pages
Full code sample which illustrates how to copy pages from one document to another, how to delete, and rearrange pages and how to use ImportPages().