itext把pdf根据制定页数拆分成新得pdf

网上看到得，改了很少得部分

public static void main(String[] args) {

partitionPdfFile("/Users/shuguang/Desktop/pdf/九型人格.pdf");

}

private static  int N = 0;
private static final int pageSize = 5;//每五页作为一个新得pdf

public static void partitionPdfFile(String filepath) 
    { 
        Document document = null; 
        PdfCopy copy = null; 
         
        try  
        { 
            PdfReader reader = new PdfReader(filepath); 
             
            int n = reader.getNumberOfPages();
            if(n%pageSize!=0){
            N = n/pageSize+1;
            }else{
            N = n/pageSize;
            }
            
            if(n < N) 
            { 
                System.out.println("The document does not have " + N + " pages to partition !"); 
                return; 
            } 
             
            int size = pageSize;          
            String staticpath = filepath.substring(0, filepath.lastIndexOf("\\")+1);             
            String savepath = null; 
            ArrayList<String> savepaths = new ArrayList<String>(); 
            for(int i=1; i<=N; i++) 
            {  //获取分批得pdf文件得路径数组
                if(i < 10) 
                { 
                    savepath = filepath.substring(filepath.lastIndexOf("\\")+1, filepath.length()-4); 
                    savepath = staticpath + savepath + "0" + i + ".pdf"; 
                    savepaths.add(savepath);                     
                } 
                else 
                { 
                    savepath = filepath.substring(filepath.lastIndexOf("\\")+1, filepath.length()-4); 
                    savepath = staticpath + savepath + i + ".pdf"; 
                    savepaths.add(savepath); 
                } 
            }            
             
            for(int i=0; i<N-1; i++) 
            {//生成除最后一个pdf得pdf文件
                document = new Document(reader.getPageSize(1)); 
                copy = new PdfCopy(document, new FileOutputStream(savepaths.get(i)));            
                document.open(); 
                for(int j=size*i+1; j<=size*(i+1); j++) 
                { 
                    document.newPage();  
                    PdfImportedPage page = copy.getImportedPage(reader, j); 
                    copy.addPage(page); 
                } 
                document.close(); 
            } 
             
              //最后一个文件单独处理，怕有页数不满足特定页数得需求
            document = new Document(reader.getPageSize(1)); 
            copy = new PdfCopy(document, new FileOutputStream(savepaths.get(N-1))); 
            document.open(); 
            for(int j=size*(N-1)+1; j<=n; j++) 
            { 
                document.newPage();  
                PdfImportedPage page = copy.getImportedPage(reader, j); 
                copy.addPage(page); 
            } 
            document.close(); 
 
        } catch (IOException e) { 
            e.printStackTrace(); 
        } catch(DocumentException e) { 
            e.printStackTrace(); 
        } 
    }