98-hutool

1. IdUtil

1. 自增主键问题

• 两张一样了表要合并，会出问题。用uuid不会出问题。自增也可能让其他人猜到下一个id

2. 雪花算法

Snowflake snowflake = IdUtil.getSnowflake(1, 1);

2. CollUtil

1. newHashSet()

public static <T> HashSet<T> newHashSet(T... ts) {
    return set(false, ts);
}

String[] split = roleCodes.split(",");
roleSet = CollUtil.newHashSet(split);

HashSet<Integer> integers = CollUtil.newHashSet(1, 2, 3);
HashSet<String> strings = CollUtil.newHashSet("li", "song", "tao");

2. sub()

ArrayList<String> list = CollUtil.newArrayList("ooxx", "xxoo", "xoxo");
List<String> sub = CollUtil.sub(list, 0, list.size() - 1);
Console.error(sub);
// [ooxx, xxoo]

3. RandomUtil

1. 8位随机数

RandomUtil.randomInt(10000000, 99999999)

4. SpringUtil

@Import(cn.hutool.extra.spring.SpringUtil.class)

@RequestMapping("/springUtil")
public void springUtil() {
    ApplicationContext applicationContext = SpringUtil.getApplicationContext();
    String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames();
    for (String beanDefinitionName : beanDefinitionNames) {
        System.out.println(beanDefinitionName);
    }
}

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