public static void main(String[] args) throws Exception {
		PdfReader reader = new PdfReader("D:/1.pdf");
		PdfStamper stamper = new PdfStamper(reader, null);
		List<String> layNames = new ArrayList<String>();
		Map<String, PdfLayer> pdfLayers = stamper.getPdfLayers();
		for (String key : pdfLayers.keySet()) {
			//这里的key虽然也是图层的名称，
			//但是是所有图层包括看不到的图层的名称，而且有多个同名的图层的话获取到的key是 图层(数字)
			PdfLayer pdfLayer = pdfLayers.get(key);
			//判断PDF图层是否显示
			if(pdfLayer.isOnPanel()){
				System.out.println(pdfLayer.get(PdfName.NAME).toString());
			}
		}
	}