【hash使用场景之房间号创建】

RandomService.java

package org.example.testjedis;

import java.util.Random;

public class RandomService {
    private static final Random r = new Random();

    
    public static int rand(int start, int end) {
        return Math.abs(r.nextInt()) % (end - start + 1) + start;
    }
}

RoomIdService.java

package org.example.testjedis;

import redis.clients.jedis.Jedis;

public class RoomIdService {
    private static final int beganRoomId = 111111;
    private static final int endRoomId = 999999;
    private static final String ROOM_ID_KEY = "roomid";

    
    public static int getRoomId() {
        int roomId = -1;
        long ret = 0;

        int count = 0;
        while (ret == 0) {
            roomId = RandomService.rand(beganRoomId, endRoomId);
            try (Jedis jedis = new Jedis()) {
                ret = jedis.hsetnx(ROOM_ID_KEY, String.valueOf(roomId), "1");
            }

            // 没找到,则说明房间号紧缺,创建房间号失败. 基本不会发生这样的情况
            if (ret == 0) {
                if (++count > 1000) {
                    roomId = -1;
                    break;
                }
            }
        }

        return roomId;
    }

    
    public static boolean delRoomId(int roomId) {
        long del = 0;
        try (Jedis jedis = new Jedis()) {
            del = jedis.hdel(ROOM_ID_KEY, String.valueOf(roomId));
        }
        return del == 1;
    }

    
    public static void clearAllRoomId() {
        System.out.println("开始清理房间号...");
        try (Jedis jedis = new Jedis()) {
            jedis.del(ROOM_ID_KEY);
        }
        System.out.println("清理房间号结束...");
    }

    
    public static int getUsedRoomIdSize() {
        long len = 0;
        try (
                Jedis jedis = new Jedis()
        ) {
            len = jedis.hlen(ROOM_ID_KEY);
        }
        return (int) len;
    }
}

Main.java

package org.example.testjedis;

import java.util.HashSet;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        RoomIdService.clearAllRoomId();

        Set roomIdSet = new HashSet<>();
        for (int i = 0; i < 88; i++) {
            int roomId = RoomIdService.getRoomId();
            if (roomId > 0) {
                roomIdSet.add(roomId);
            } else {
                System.err.println("创建房间失败");
            }
        }

        System.out.println(roomIdSet);
        System.out.println(roomIdSet.size());
        System.out.println(RoomIdService.getUsedRoomIdSize());
    }
}

总结：对于全球同服这种，房间号统一管理用redis则非常方便