// 搜索pdf
    public List<String> searchPdfFile(String keyword,List<String> items) throws IOException {
        File f = new File("/sdcard/LPR/lpr_pdf/");// 这是对应文件名
        File[] fileList = f.listFiles();
        PDDocument document = null;
        for(File filePdf : fileList)
        {
            Toast.makeText(EntAppSea.this, filePdf.getName(),
                    Toast.LENGTH_LONG).show();
           PDFTextStripper stripper = new PDFTextStripper();
           document = PDDocument.load(filePdf);
           int pageNum = document.getNumberOfPages();
           Toast.makeText(EntAppSea.this, String.valueOf(pageNum),
                    Toast.LENGTH_LONG).show();
           
           for(int i=1;i<=pageNum;i++)
           {
               stripper.setStartPage(i);
               stripper.setEndPage(i+1);
               String pdfStr = stripper.getText(document);
               if(pdfStr.indexOf(keyword)>-1)
               {
                 items.add(filePdf.getName()+"第"+i+"页");
               }
           }
        }
        return items;
    }