java 如何产生随机数 不是伪随机数

```java

import java.util.concurrent.atomic.AtomicLong;

import java.security.SecureRandom;

public class TrueRandomNumberGenerator {

private static final AtomicLong seed = new AtomicLong(System.nanoTime());

private static final SecureRandom secureRandom = new SecureRandom();

public static long generateTrueRandomNumber() {

seed.set(System.nanoTime());

return secureRandom.nextLong();