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 connectionspoolConfig.setMaxIdle(100);  // maximum idle connectionsjedisPool = 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);}
}