请不要将随机生成的字节数组转换为字符串，因为有很多值无法编码为字符串—请考虑x00。
将这样的字节数组“转换”为字符串的常用方法是字节数组的base64编码。这将使字符串延长约1/3，但可以无损地将字符串重新编码到字节数组中。
请注意不要使用 Random 但是 SecureRandom 作为这些数据的来源。
输出：

length of bytes before converting to String: 16
ivBase64: +wQtdbbbFdvrorpFb6LRTw==
length of bytes after converting to String: 16
ivSpec equals to ivRedecoded: true

代码：

import javax.crypto.spec.IvParameterSpec;
import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Base64;
public class Main {
    public static void main(String[] args) {
        //Random rand = new SecureRandom();
        SecureRandom rand = new SecureRandom();
        byte[] bytes = new byte[16];
        rand.nextBytes(bytes);
        IvParameterSpec ivSpec = new IvParameterSpec(bytes);
        System.out.println("length of bytes before converting to String: " + ivSpec.getIV().length);
        //String ibString = new String(ivSpec.getIV());
        String ivBase64 = Base64.getEncoder().encodeToString(ivSpec.getIV());
        System.out.println("ivBase64: " + ivBase64);
        byte[] ivRedecoded = Base64.getDecoder().decode(ivBase64);
        //System.out.println("length of bytes after converting to String: " + ibString.getBytes().length);
        System.out.println("length of bytes after converting to String: " + ivRedecoded.length);
        System.out.println("ivSpec equals to ivRedecoded: " + Arrays.equals(ivSpec.getIV(), ivRedecoded));
    }
}