如何在Android中将字节数组转换为PDF文件？

File dir = Environment.getExternalStorageDirectory();
        文件辅助=新文件(“/ mnt / sdcard / Sample.pdf”);
        尝试{
            inputStream fis = new FileInputStream(assist);

long length = assist.length();
        if (length > Integer.max_value) {
            Log.e("MainActivity","cAnnnottt   readddd");
        }
        byte[] bytes = new byte[(int) length];
        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length && (numRead = fis.read(bytes,offset,bytes.length - offset)) >= 0) {
            offset += numRead;
        }

        File data = new File(dir,"mydemo.pdf");
        OutputStream op = new FiLeoutputStream(data);
        op.write(bytes);
    }catch (Exception eX){
        Log.e("MainActivity",""+ex.getmessage())
    }