private String bytesToHexString(byte[] bytes) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < bytes.length; i++) {
System.out.println("bytes[i} "+bytes[i]);
String hex = Integer.toHexString(0xFF & bytes[i]);
//为什么length()为1要加0
if (hex.length() == 1) {
sb.append('0');
}
sb.append(hex);
}