public static List<byte[]> pdf2image(String pdfFilePath) throws Exception{

        File tempDir = null;

        try{

            tempDir = Files.createTempDir();

            Process proc = new ProcessBuilder("gs", "-sDEVICE=pngalpha", "-o", tempDir + File.separator + "%03d.png", "-sDEVICE=pngalpha", "-r144", pdfFilePath)

                               .redirectErrorStream(true)

                               .start(); 

            ArrayList<String> output = new ArrayList<String>();

            BufferedReader br = new BufferedReader(new InputStreamReader(proc.getInputStream()));

            String line = null;

            while ((line = br.readLine()) != null)

                output.add(line);

            logger.info("执行gs命令的输出：" + StringUtils.join(output, System.lineSeparator()));

            if (0 != proc.waitFor())

                throw new Exception("转换失败");

            File[] files = tempDir.listFiles();

            Arrays.sort(files, new Comparator<File>() {

                public int compare(File f1, File f2) {

                    return f1.getName().compareTo(f2.getName());

                }

            });

            List<byte[]> images = new ArrayList<>();

            for(File file : files)

                images.add(IOUtils.toByteArray(new FileInputStream(file)));

            return images;

        }finally{

            if(tempDir != null)

                FileUtils.deleteDirectory(tempDir);

        }

    }