Itext Pdf 生成 框架

try{
    String outPath = inPath.replaceAll(".pdf","_ok.pdf");
    PdfReader reader  = new PdfReader(inPath);            
    Rectangle cropBox = reader.getCropBox(1);
    float pageWidth = cropBox.getWidth();
    float pageHeight = cropBox.getHeight();
    int pageCount = reader.getNumberOfPages();
    Document document = new Document(new Rectangle(pageWidth, pageHeight));//新建一个文档并且设置页面大小
    FileOutputStream outputStream =  new FileOutputStream(outPath);//新建一个pdf文档;

    PdfWriter writer = PdfWriter.getInstance(document, outputStream);//把新建的pdf 赋值给 document
    writer.setPdfVersion(PdfWriter.VERSION_1_5);
    document.open();//打开 document文档
    PdfContentByte cb = writer.getDirectContent();


    outputStream.flush();//关闭文件
    document.close();//关闭文件
    outputStream.close();//关闭文件
    reader.close();
}catch (Exception e){
    e.printStackTrace();
}