Java隨機數生成器：Random，ThreadLocalRandom，SecureRandom

@Test

public void getItemID(int n) {//n需要的長度

String val = "";

Random random = new Random();

for (int i = 0; i < n; i++) {

String str = random.nextInt(2) % 2 == 0 ? "num" : "char";

if ("char".equalsIgnoreCase(str)) { // 產生字母

int nextInt = random.nextInt(2) % 2 == 0 ? 65 : 97;

// System.out.println(nextInt + "!!!!"); 1,0,1,1,1,0,0

val += (char) (97 + random.nextInt(26));

} else if ("num".equalsIgnoreCase(str)) { // 產生數字

val += String.valueOf(random.nextInt(10));

}

}

System.out.println(val);

}

https://blog.csdn.net/qinchao_mei/article/details/80320896