redis新手入门，摸不着头脑可以看看<三>——lrange分页

看了几天 redis开发与运维，写了个小demo练练手，直接上代码。

1.首先是数据库，本地要有redis，具体的如何安装redis，官网下个就好了，sososo。

2.启动redis

注意启动命令。另，我的redis数据是通过单元测试直接写到数据库里的，贴一下

 1 @Test
 2     public void testJedisPool1(){
 3         //create a simple and not-safe pool
 4         GenericObjectPoolConfig config = new GenericObjectPoolConfig();
 5         //init connect pool
 6         JedisPool jedisPool = new JedisPool(config,"127.0.0.1",6379);
 7         Jedis jedis = null;
 8         try {
 9             jedis = jedisPool.getResource();
10             for (int i = 1; i <= 100000; i++) {
11                 jedis.rpush("nameList","zl"+i);
12             }//代码还是自己敲的为好
13             out.println("write ok");
14         } catch (Exception e) {
15             e.printStackTrace();
16         } finally {
17             if (jedis != null){
18                 jedis.close();
19             }
20         }
21     }

3.controller

 1 /**
 2  * create by zl on 2018/2/23
 3  *
 4  */
 5 @RequestMapping("/milu")
 6 @Controller
 7 public class PagingController {
 8     @RequestMapping("/paging")
 9     public String paging(Model model,Long currentPage){
10 
11 
12         //create a simple and not-safe pool
13         GenericObjectPoolConfig config = new GenericObjectPoolConfig();
14         //init connect pool
15         JedisPool jedisPool = new JedisPool(config,"127.0.0.1",6379);
16         Jedis jedis = null;
17         try {//别偷懒
18             jedis = jedisPool.getResource();
19             //total
20             long total = jedis.llen("nameList");
21             //size
22             long size = 399L;
23             if (total/size==0){
24                 total = total/size;
25             }else {
26                 total = total/size + 1;
27             }
28             // set currentPage
29             currentPage = currentPage==null?0L:currentPage;
30             out.println(total);
31             List<String> nameList = jedis.lrange("nameList",currentPage*size,(currentPage+1)*size);
32             model.addAttribute("nameList",nameList);
33             model.addAttribute("total",total);
34             model.addAttribute("currentPage",currentPage);
35             for (String name : nameList) {
36                 out.println(name);
37             }
38         } catch (Exception e) {
39             e.printStackTrace();
40         } finally {
41             if (jedis != null){
42                 jedis.close();
43             }
44         }
45         return "paging";
46     }
47 }

4,.页面就很简单了

 1 <%--
 2   Created by zl.
 3   Date: 2018/2/23
 4   Time: 17:53
 5   To change this template use File | Settings | File and Code Templates.
 6 --%>
 7 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
 8 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
 9 <%@ page isELIgnored="false" %>
10 <html>
11     <head>
12         <title>测试</title>
13     </head>
14     <style>
15         ul{
16             list-style: none;
17             float: left;
18         }
19         li{
20             width: 50px;
21             height: 50px;
22         }
23     </style>
24     <script type="text/javascript" src="${pageContext.request.contextPath}/assets/js/jquery.min.js"></script>
25     <body>
26         <form action="${pageContext.request.contextPath}/milu/paging">
27             按页数查询：<input class="pageNum" name="currentPage" maxlength="10" value="输入要查询的页数">
28             <input type="submit" value="查询"><br><hr>
29         </form>
30         <strong>用户名称：</strong><br><hr>
31         <ul>
32             <c:forEach items="${nameList}" var="n">
33                 <li>${n}</li>
34             </c:forEach>
35         </ul>
36         <br><hr>
37         <a href="${pageContext.request.contextPath}/milu/paging?currentPage=${currentPage-1}">上一页</a>
38         当前第${currentPage+1}页，共${total}页
39         <a href="${pageContext.request.contextPath}/milu/paging?currentPage=${currentPage+1}">下一页</a>
40     </body>
41 </html>

5.效果图

 

 写在最后的，书中好像有写到lrange在高并发下可能会造成redis阻塞，应该用scan啥啥来着，忘了，有时间再补上

这里要纠正一下，redis开发与运维 中写的是 lrange在列表的两端性能较好，若列表较大，获取中间范围的元素性能会变差

从上图也可以看的出来lrange的时间复杂度的计算方式.

 

posted @ 2018-02-24 11:51  夜旦  阅读(2530)  评论(0)  编辑  收藏  举报