private static String jarPath = Encrypt.class.getProtectionDomain().getCodeSource().getLocation().getFile();
URL url=new URL("jar:file:" + jarPath + "!/a.txt"); InputStream fis = url.openStream(); ByteArrayOutputStream bos = new ByteArrayOutputStream(); byte[] buf = new byte[1024]; int read = -1; while ((read = fis.read(buf)) > 0) { bos.write(buf,0,read); } String base64Str = new String(bos.toByteArray());