redis-实现排行榜
使用redis的有序集合zset实现排行榜功能，步骤有：
1、下载jedis-2.7.2.jar
<dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.7.2</version> <type>jar</type> <scope>compile</scope> </dependency>
2、下载jackson所需的jar包
使用jackson实现数据的序列化和反序列化
<dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.5.4</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.5.4</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.5.4</version> </dependency>
3、初始化JedisPool对象，并通过JedisPool创建Jedis对象
public class JedisHandler {
private static JedisPool jedisPool = null;
static {
JedisPoolConfig poolConfig = new JedisPoolConfig();
poolConfig.setMaxTotal(8); // maximum active connections
poolConfig.setMaxIdle(100); // maximum idle connections
jedisPool = new JedisPool(poolConfig, "127.0.0.1", 6379);
}
public static Jedis createJedis() {
return jedisPool.getResource();
}
}
4、创建数据模型对象
public class User {
private String id;
private String userName;
private Integer gender;
private String redisterDate;
private Double score;
/** 排名 */
private Integer rank;
...
...
...
}
5、通过jedis添加模拟数据
public static void setData() {
Jedis jedis = JedisHandler.createJedis();
User user = new User("100", "汤姆", 1, "2012-10-20");
jedis.zadd("user:score", 1000d, MarshalJSONUtil.marshalBeanToJson(user));
user = new User("101", "韩梅梅", 2, "2013-03-10");
jedis.zadd("user:score", 873.3, MarshalJSONUtil.marshalBeanToJson(user));
user = new User("102", "Jack", 1, "2008-11-10");
jedis.zadd("user:score", 1302.6d, MarshalJSONUtil.marshalBeanToJson(user));
user = new User("103", "Rose", 2, "2015-02-03");
jedis.zadd("user:score", 200d, MarshalJSONUtil.marshalBeanToJson(user));
user = new User("104", "李雷", 1, "2014-01-26");
jedis.zadd("user:info", 534.73d, MarshalJSONUtil.marshalBeanToJson(user));
Random random = new Random();
for(int i = 1; i < 101; i++) {
int index = 104 + i;
user = new User(index + "", "用户" + index, random.nextInt(1) + 1, "2015-01-26");
jedis.zadd("user:score", 100d + 1, MarshalJSONUtil.marshalBeanToJson(user));
}
jedis.close();
}
6、通过jedis排序，筛选数据
/**
* 获取降序排列的数据
* @return 排名后的用户集合
*/
public static List<User> getRevRankData(int count) {
Jedis jedis = JedisHandler.createJedis();
List<User> list = new ArrayList<User>();
try {
Set<Tuple> set = jedis.zrevrangeWithScores("user:score", 0, count);
Iterator<Tuple> iterator = set.iterator();
int rank = 1;
while(iterator.hasNext()) {
Tuple tuple = iterator.next();
String userInfo = tuple.getElement();
User user = MarshalJSONUtil.marshalToBean(userInfo, User.class);
user.setScore(tuple.getScore());
user.setRank(rank++);
list.add(user);
}
} catch(Exception e) {
e.printStackTrace();
} finally {
jedis.close();
}
return list;
}
7、创建处理请求的Servlet
public class RankServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String type = request.getParameter("type");
String countStr = request.getParameter("count");
int count = (countStr == null || "".equals(countStr)) ? -1 : Integer.parseInt(countStr);
List<User> list = null;
if("asc".equalsIgnoreCase(type)) {
list = RankUtil.getRankData(count);
} else {
list = RankUtil.getRevRankData(count);
}
request.setAttribute("list", list);
request.getRequestDispatcher("/rank.jsp").forward(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}