Redis从基础命令到实战之有序集合类型(SortedSet)

有序集合类型是Redis五种数据类型中最高级的、也是最复杂的类型。有序集合具有集合类型的特性，在其基础上给每个元素关联了一个分值，或称为权重，操作时既可以在添加元素时指定分值，也可以单独修改集合中某一个元素的分值。使用时可以按分值排序(从低到高或从高到低)并顺序读取全部或某一范围内的元素，或者获得某一分值范围内的元素。利用这一特点，可以很方便的实现排行榜、热门文章等功能。

在本节的实例中，使用有序集合类型为商品管理模块添加一个按浏览量排序的功能。

一、常用命令

import java.util.Set;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.Tuple;

public class SortedSetExample {

    public static void main(String[] args) {
        Jedis jedis = JedisProvider.getJedis();
        jedis.flushDB();

        // 向有序集合中加入元素, 成功返回1, 失败返回0
        Long zadd = jedis.zadd("fruit", 5.0, "apple");
        print("zadd fruit apple=" + zadd);
        // 重复添加, 会修改权重
        zadd = jedis.zadd("fruit", 6.0, "apple");
        print("zadd fruit apple again=" + zadd);

        jedis.zadd("fruit", 2.0, "banana");
        jedis.zadd("fruit", 4.0, "orange");
        jedis.zadd("fruit", 8.0, "grape");
        jedis.zadd("fruit", 10.0, "lemon");
        jedis.zadd("fruit", 7.0, "cherry");

        // 统计元素个数
        print("zcard fruit=" + jedis.zcard("fruit"));

        // 统计某个权重范围内元素个数
        print("zcount fruit [1.0,5.0]=" + jedis.zcount("fruit", 1.0, 5.0));

        // 查看排名
        print("zrank fruit grape=" + jedis.zrank("fruit", "grape"));
        print("zrevrank fruit grape=" + jedis.zrevrank("fruit", "grape"));

        // 按权重排序后读取索引范围内元素及权重
        System.out.println("zrangeWithScores fruit");
        Set<Tuple> tuples = jedis.zrangeWithScores("fruit", 0, -1);
        for (Tuple t : tuples) {
            System.out.println(t.getElement() + ":" + t.getScore());
        }
        System.out.println("------------------------------------------------------");
        System.out.println();

        // 按权重反向排序后读取索引范围内元素及权重
        System.out.println("zrevrangeWithScores fruit");
        tuples = jedis.zrevrangeWithScores("fruit", 0, -1);
        for (Tuple t : tuples) {
            System.out.println(t.getElement() + ":" + t.getScore());
        }
        System.out.println("------------------------------------------------------");
        System.out.println();

        // 按权重排序后读取索引范围内元素
        Set<String> set = jedis.zrange("fruit", 1, 3);
        print("zrange fruit [1,3]=" + set);

        // 按权重反向排序后读取索引范围内元素
        set = jedis.zrevrange("fruit", 1, 3);
        print("zrevrange fruit [1,3]=" + set);

        // 读取权重在指定范围内的元素及其权重并按权重排序
        System.out.println("zrangeByScoreWithScores fruit [1.0,8.0]");
        tuples = jedis.zrangeByScoreWithScores("fruit", 1.0, 8.0);
        for (Tuple t : tuples) {
            System.out.println(t.getElement() + ":" + t.getScore());
        }
        System.out.println("------------------------------------------------------");
        System.out.println();

        // 读取权重在指定范围内的元素及其权重并按权重反向排序
        System.out.println("zrevrangeByScoreWithScores fruit [8.0,1.0]");
        tuples = jedis.zrevrangeByScoreWithScores("fruit", 8.0, 1.0);
        for (Tuple t : tuples) {
            System.out.println(t.getElement() + ":" + t.getScore());
        }
        System.out.println("------------------------------------------------------");
        System.out.println();

        // 读取权重在指定范围内的元素并按权重排序
        set = jedis.zrangeByScore("fruit", 1.0, 7.0);
        print("zrangeByScore fruit [1.0,7.0]=" + set);

        // 读取权重在指定范围内的元素并按权重反向排序
        set = jedis.zrevrangeByScore("fruit", 7.0, 1.0);
        print("zrevrangeByScore fruit [7.0,1.0]=" + set);

        // 查看集合中指定元素的权重
        double zscore = jedis.zscore("fruit", "grape");
        print("zscore fruit grape=" + zscore);

        // 修改指定元素权重
        print("zincrby fruit -2 grape=" + jedis.zincrby("fruit", -2, "grape"));
        print("zincrby fruit 5.0 lemon=" + jedis.zincrby("fruit", 5.0, "lemon"));
        print("after zincrby: zscore fruit grape=" + jedis.zscore("fruit", "grape"));

        // 删除元素
        print("zrem fruit cherry=" + jedis.zrem("fruit", "cherry"));
        print("zremrangeByScore fruit [3.0,6.0]=" + jedis.zremrangeByScore("fruit", 3.0, 6.0));

        jedis.close();
    }

    private static void print(String info) {
        System.out.println(info);
        System.out.println("------------------------------------------------------");
        System.out.println();
    }
}

二、实践练习
在上一节的基础上，给每个商品增加一个浏览量的记录，商品每次被浏览，设置浏览量加1。

首先修改添加商品的代码，设置商品的初始浏览量为0。

/**
 * 添加一个商品
 * @param goods
 * @return
 */
public boolean addGoods(Goods goods) {
    long id = getIncrementId();
    Map<String, String> map = new HashMap<>();
    map.put("id", String.valueOf(id));
    map.put("title", goods.getTitle());
    map.put("price", String.valueOf(goods.getPrice()));

    //随机获得三个分类
    String size = SIZE[new Random().nextInt(SIZE.length)];
    String color = COLOR[new Random().nextInt(COLOR.length)];

    String key = "goods:" + id;
    boolean added = jedis.hmset(key, map).equals("OK");
    if(added) {
        jedis.rpush("goods:list", String.valueOf(id));
        //初始浏览量默认为0
        jedis.zadd("goods:views", 0, String.valueOf(id));
        //记录商品所属分类
        jedis.sadd("goods:" + id + ":tags", size, color);
        //记录每个分类下包含的商品ID
        jedis.sadd("tag:" + size + ":goods", String.valueOf(id));
        jedis.sadd("tag:" + color + ":goods", String.valueOf(id));
    }
    return added;
}

用户浏览商品方法，浏览量加1。

/**
 * 浏览商品
 * @param id
 */
public void view(long id) {
    jedis.zincrby("goods:views", 1, String.valueOf(id));
}

按浏览量排序

/**
 * 读取商品列表并按浏览量排序
 * @param pageIndex
 * @param pageSize
 * @return
 */
public List<Goods> getGoodsListOrderByViews(int pageIndex, int pageSize) {
    int totals = (int)getTotalCount();
    int from = (pageIndex - 1) * pageSize;
    if(from < 0) {
        from = 0;
    }
    else if(from > totals) {
        from = (totals / pageSize) * pageSize;
    }
    int to = from + pageSize - 1;
    if(to > totals) {
        to = totals;
    }
    List<Goods> goodsList = new ArrayList<>();
    Set<String> idList = jedis.zrevrange("goods:views", from, to);
    for(String id : idList) {
        String key = "goods:" + id;
        Map<String, String> maps = jedis.hgetAll(key);
        Goods goods = new Goods();
        goods.setId(NumberUtils.toLong(maps.get("id")));
        goods.setTitle(maps.get("title"));
        goods.setPrice(NumberUtils.toFloat(maps.get("price")));
        //读取分类
        goods.setTags(jedis.smembers("goods:" + id + ":tags"));
        goodsList.add(goods);
    }
    return goodsList;
}

测试代码

public static void main(String[] args) {
    SortedSetLession sl = new SortedSetLession();
    sl.clear();

    //添加一批商品
    for(int i = 0; i< 42; i++) {
        Goods goods = new Goods(0, "goods" + String.format("%05d", (i + 1)), i);
        sl.addGoods(goods);
    }
    //读取商品总数
    System.out.println("商品总数: " + sl.getTotalCount());
    //删除第29件商品
    sl.delGoods(29);
    System.out.println("删除后商品总数: " + sl.getTotalCount());
    //分页显示
    List<Goods> list = sl.getGoodsList(2, 20);
    System.out.println("第二页商品:");
    for(Goods goods : list) {
        System.out.println(goods);
    }
    //按分类查找
    List<Goods> listByTag = sl.findGoodsByTag("big", "green");
    System.out.println("所有尺寸为big,颜色为green的商品:");
    for(Goods goods : listByTag) {
        System.out.println(goods);
    }
    //模拟点击商品
    sl.view(3);
    sl.view(3);
    sl.view(4);
    //按点击量排序
    List<Goods> listWithOrder = sl.getGoodsListOrderByViews(1, 20);
    System.out.println("按点击量排序:");
    for(Goods goods : listWithOrder) {
        System.out.println(goods);
    }
}

源码下载