如何利用java.security.secureRandom生成指定长度的盐 用于sha1加密？

public class SaltGenerate {
    public static void main(String[] args) throws UnsupportedEncodingException {
        Random ranGen = new SecureRandom();
        byte[] aesKey = new byte[20];
        ranGen.nextBytes(aesKey);
        StringBuffer hexString = new StringBuffer();
        for (int i = 0; i < aesKey.length; i++) {
            String hex = Integer.toHexString(0xff & aesKey[i]);
            if (hex.length() == 1)
                hexString.append('0');
            hexString.append(hex);
        }
        System.out.println(hexString);
    }
}