MD5加密算法
第一种：使用jdk自带的java.security.MessageDigest实现
String plainText = "admin";
byte[] secretBytes = null;
try {
secretBytes = MessageDigest.getInstance("md5").digest(
plainText.getBytes());
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException("没有这个md5算法！");
}
String md5code = new BigInteger(1, secretBytes).toString(16);
for (int i = 0; i < 32 - md5code.length(); i++) {
md5code = "0" + md5code;
}
System.out.println(md5code);
第二种：使用spring自带的DigestUtils实现
DigestUtils.md5DigestAsHex("admin".getBytes())
