https://blog.csdn.net/wangfei0904306/article/details/71565968
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不过是个MD5，网上随便搜了个，竟然时好时坏，真是误事，这个从系统里扒拉出来的，还比较靠谱
private String MD5(String s) {
try {
MessageDigest md = MessageDigest.getInstance("MD5");
byte[] bytes = md.digest(s.getBytes("utf-8"));
return toHex(bytes);
}
catch (Exception e) {
throw new RuntimeException(e);
}
}
private static String toHex(byte[] bytes) {
final char[] HEX_DIGITS = "0123456789ABCDEF".toCharArray();
StringBuilder ret = new StringBuilder(bytes.length * 2);
for (int i=0; i<bytes.length; i++) {
ret.append(HEX_DIGITS[(bytes[i] >> 4) & 0x0f]);
ret.append(HEX_DIGITS[bytes[i] & 0x0f]);
}
return ret.toString();
}