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