PasswordHelper 对user对象的password进行加密重设

public class PasswordHelper {
    private RandomNumberGenerator randomNumberGenerator =
     new SecureRandomNumberGenerator();
    private String algorithmName = "md5";
    private final int hashIterations = 2;
    public void encryptPassword(User user) {
        user.setSalt(randomNumberGenerator.nextBytes().toHex());
        String newPassword = new SimpleHash(
                algorithmName,
                user.getPassword(),
                ByteSource.Util.bytes(user.getCredentialsSalt()),
                hashIterations).toHex();
        user.setPassword(newPassword);
    }
} 

　　在创建账户及修改密码时直接把生成密码操作委托给PasswordHelper。