package com.consum.base.core.util;
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import com.consum.base.util.IdUtil;
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import lombok.extern.slf4j.Slf4j;
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import org.springframework.security.crypto.codec.Hex;
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import java.nio.charset.StandardCharsets;
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import java.security.MessageDigest;
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import java.util.HashMap;
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import java.util.Map;
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/**
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* 功能描述：获取随机值
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*
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* @author dhz
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* @date 2023-10-16 11:20
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* @Version 1.0
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**/
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@Slf4j
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public class RandomUtil {
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/**
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* 加盐字符串
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*/
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private static final String SALT = "13";
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/**
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* 获取分组序号
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*
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* @param id 分组业务主键id
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* @param group 分组数 从0开始到 group-1 共group 组
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* @return 分组数
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*/
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public static Integer getRandom(Long id, Integer group) {
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try {
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MessageDigest md5 = MessageDigest.getInstance("md5");
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byte[] digest = md5.digest((id + SALT).getBytes(StandardCharsets.UTF_8));
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char[] encode = Hex.encode(digest);
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Long parseLong = Long.parseLong(String.valueOf(encode).substring(0, 3), 16);
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return (int) (parseLong % group);
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} catch (Exception e) {
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log.error(e.getMessage());
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}
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return -1;
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}
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public static void main(String[] args) {
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Map<Integer, Integer> map = new HashMap<Integer, Integer>(2);
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Integer group = 13;
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long generateId = IdUtil.generateId();
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for (int i = 0; i < 10000; i++) {
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Integer random = RandomUtil.getRandom(generateId, group);
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if (map.containsKey(random)) {
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map.put(random, map.get(random) + 1);
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} else {
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map.put(random, 1);
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}
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}
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System.out.println(map);
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}
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}
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