简单实现分流功能

逻辑比较简单就是对字符串一顿加解密操作然后hashcode然后取模100，然后看取模结果落在哪个组的区间

代码

import lombok.extern.slf4j.Slf4j;
import org.springframework.util.CollectionUtils;
import org.springframework.util.DigestUtils;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.*;

@Slf4j
public class Percent {
    /**
     * 流量切分算法（随机）
     *
     * @param rid       rid
     * @param groupMap 对照组
     * @return 分组
     */
    public static String choose(String rid, Map<String, Double> groupMap) {
        if (groupMap == null) {
            return null;
        }
        List<String> groups = new ArrayList<>(groupMap.keySet());
        List<Double> rates = new ArrayList<>(groupMap.values());
        if (CollectionUtils.isEmpty(groupMap) || CollectionUtils.isEmpty(rates)) {
            return null;
        }

        String digest = DigestUtils.md5DigestAsHex(rid.getBytes());
        int hashCode = digest.hashCode();
        //百分比
        int random = Math.abs(hashCode) % 100;
        //murmur3_32算法比较好，分布很均匀
        //int random = Math.abs(Hashing.murmur3_32().hashString(rid, Charset.forName("utf-8")).asInt())%100;

        double start = 0.0;
        double end = 0.0;

        for (int i = 0; i < rates.size(); i++) {
            end = end + rates.get(i);
            if (start <= random && random < end) {
                String group = groups.get(i);
                for (String tempGroup : groups) {
                    if (group.equals(tempGroup)) {
                        log.info("choose [rid]: {} [group]: {} random ;{}", rid, group, random);
                        return group;
                    }
                }
            }
            start = start + rates.get(i);
        }
        return null;
    }

}

测试

写个main方法测试一下

public static void main(String[] args) {
    Map<String, Double> groups = new HashMap<>();
    groups.put("g1", 15d);
    groups.put("g2", 25d);
    groups.put("g3", 30d);
    groups.put("g4", 30d);
    Map<String, Integer> groupCountMap = new HashMap<>();
    long total = 100000;
    for (long i = 0; i < total; i++) {
        String group_super_id = choose(UUID.randomUUID().toString(), groups);
        if (!groupCountMap.containsKey(group_super_id)) {
            groupCountMap.put(group_super_id, 1);
        }
        groupCountMap.put(group_super_id, groupCountMap.get(group_super_id) + 1);
    }
    for (Map.Entry<String, Integer> entry : groupCountMap.entrySet()) {
        log.info("group : {} count : {} percent :{}", entry.getKey(), entry.getValue(), new BigDecimal(entry.getValue()).divide(new BigDecimal(total), 4, RoundingMode.UP).multiply(new BigDecimal(100)) + "%");
    }
}

结果逼近预设值