经过一番研究和一些工作，我终于可以对密码进行哈希处理了，现在有一个问题在我的脑海中，我已经使用了SHA1方法，我想尝试使用SHA512，因为被告知更好（更安全），因此以下是我的代码，尽管有点，但我认为它是可以理解的：

public class Safety
{
   //calling some parameters for possible later changes
   public static final String algorithm = "PBKDF2WithHmacSHA1";
   public static final int saltbytesize = 24;
   public static final int hashbytesize = 24;
   public static final int iterations = 1000;
   public static final int iIndex = 0;
   public static final int sIndex = 1;
   public static final int pbkIndex = 2;

   public static Users passwordHash(Users user) throws NoSuchAlgorithmException,
                                                       InvalidKeySpecException
   {
      SecureRandom sR = new SecureRandom();

      byte[] pws = new byte[saltbytesize];

      sR.nextBytes(pws);
      byte[] pwh = pbkdf2(user.getPassword().toCharArray(), pws, iterations, hashbytesize);

      user.setPassword(toHex(pwh));

      byte[] sas = new byte[saltbytesize];

      sR.nextBytes(sas);

      byte[] sah = pbkdf2(user.getsA().toCharArray(), sas, iterations, hashbytesize);

      user.setsA(toHex(sah));

      user.setUserhash(pws);

      user.setSahash(sas);

      return user;
   }

   public static boolean hashpassword(String username, String password, Users user)
   throws NoSuchAlgorithmException,
          InvalidKeySpecException
   {
      byte[] pws = user.getUserhash();

      byte[] pwh = pbkdf2(password.toCharArray(), pws, iterations, hashbytesize);

      String searcher = toHex(pwh) + username;

      String searched = user.getPassword() + user.getUsername();

      if (searcher.equals(searched))
      {
         return true;
      }
      return false;
   }

   private static byte[] pbkdf2(char[] password, byte[] salt,
                                int iterations, int bytes)
      throws NoSuchAlgorithmException, InvalidKeySpecException
   {
      PBEKeySpec spec = new PBEKeySpec(password, salt, iterations, bytes * 8);
      SecretKeyFactory skf = SecretKeyFactory.getInstance(algorithm);
      return skf.generateSecret(spec).getEncoded();
   }

   private static String toHex(byte[] array)
   {
      BigInteger bi = new BigInteger(1, array);

      String hex = bi.toString(16);

      int paddingLength = (array.length * 2) - hex.length();

      if (paddingLength > 0)
         return String.format("%0" + paddingLength + "d", 0) + hex;
      else
         return hex;
   }
}

这就是我的代码，但是，我还无法制作SHA512，我已经尝试过了，public static final String algorithm = "PBKDF2WithHmacSHA512"但这似乎不是算法的正确字符串，因为它没有引发此类算法异常。

我也欢迎任何可以使代码更好的更改。

如上所述！相关的几行代码

公共静态最终字符串算法=“ PBKDF2WithHmacSHA512” <<<<<