需求：有一个标(理解成抢红包也行，accountBalance预赋值1000元)，大家可以抢购，每个用户抢购成功后，更新最后标的总数，在并发情况下，使用redis的乐观锁，保证更新标总值正确性，先往redis放一个标的金额：
set accountBalance "1000"
实现方式如下：
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>mybatisPage</groupId>
<artifactId>page</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>PageHelperSample</name>
<url>http://git.oschina.net/free/Mybatis-Sample</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<!-- jstl -->
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.1.2</version>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>
<!-- jstl -->
<dependency>
<groupId>commons-pool</groupId>
<artifactId>commons-pool</artifactId>
<version>1.6</version>
</dependency>
<!-- log mybatis sql -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.5</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.5</version>
</dependency>
<!-- log mybatis sql -->
<!-- fastjson -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.5</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.4</version>
</dependency>
<!-- web -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
<version>3.7.4</version>
</dependency>
<dependency>
<groupId>com.github.jsqlparser</groupId>
<artifactId>jsqlparser</artifactId>
<version>0.9.1</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.2.5</version>
</dependency>
<!-- util -->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.1</version>
</dependency>
<!-- mysql -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.35</version>
</dependency>
<!-- redis -->
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.1.0</version>
<type>jar</type>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.6</source>
<target>1.6</target>
<encoding>utf-8</encoding>
</configuration>
</plugin>
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>8.0.0.M3</version>
</plugin>
</plugins>
</build>
</project>
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>bid</servlet-name>
<servlet-class>com.heli.mybatis.page.servlet.ReidsMatchServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>bid</servlet-name>
<url-pattern>/bid</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>list</servlet-name>
<servlet-class>com.heli.mybatis.page.servlet.ReidsMatchListServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>list</servlet-name>
<url-pattern>/list</url-pattern>
</servlet-mapping>
</web-app>
servlet
package com.heli.mybatis.page.servlet;
import java.io.IOException; import java.util.List; import java.util.Random; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.lang3.StringUtils; import com.commnon.RedisAPI; import redis.clients.jedis.Jedis; import redis.clients.jedis.JedisPool; import redis.clients.jedis.Transaction; public class ReidsMatchServlet extends HttpServlet { public static JedisPool pool = RedisAPI.getPool(); // RedisAPI.set("accountBalance", "999999999");// 标还剩999999999块钱 private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Jedis jedis = pool.getResource(); long start = System.currentTimeMillis(); int flag = 0; try { flag = bid(request, response, jedis); } catch (Exception e) { e.printStackTrace(); response.getWriter().write("fail buy"); } finally { pool.returnBrokenResource(jedis); RedisAPI.returnResource(pool, jedis); } if (flag == 1) { response.getWriter().write("success buy"); } else if (flag == 2) { response.getWriter().write("have buy"); } else if (flag == 0) { response.getWriter().write("bid is zero ,you can not buy"); }else{ response.getWriter().write("fail buy"); } long end = System.currentTimeMillis(); System.out.println("--------------------------------------------请求耗时：" + (end - start) + "毫秒"); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } private int bid(HttpServletRequest request, HttpServletResponse response, Jedis jedis) throws Exception { int flag = 0;// 1,成功,2已经购买，3已经没钱了，其他異常 // 每个请求对应一个userId int userId = new Random().nextInt(999999); // 观察 总标值，每人抢购一元 while ("OK".equals(jedis.watch("accountBalance"))) { // 判断是否购买过 Boolean isBuy = RedisAPI.sismember("userIdSet", userId + ""); if (isBuy) { flag = 2; return flag; } //投资额 int r = 1;// new Random().nextInt(2); int lastAccount = 0; String balance = RedisAPI.get("accountBalance"); if (StringUtils.isNotBlank(balance)) { lastAccount = Integer.valueOf(balance) - r; } if (lastAccount < 0) { flag = 3; break; } Transaction tx = jedis.multi(); tx.set("accountBalance", lastAccount + ""); List<Object> result = tx.exec(); if (result == null || result.isEmpty()) { jedis.unwatch(); } else { System.out.println("恭喜您，" + userId + "已经中标" + r + "元，标余额" + lastAccount + "元"); RedisAPI.set(Thread.currentThread().getName(), r + ""); RedisAPI.sadd("userIdSet", userId + ""); flag = 1; break; } } return flag; } }
package com.heli.mybatis.page.servlet;
import java.io.IOException; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Set; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.commnon.RedisAPI; import redis.clients.jedis.Jedis; import redis.clients.jedis.JedisPool; public class ReidsMatchListServlet extends HttpServlet { public static JedisPool pool= RedisAPI.getPool();; public static Jedis jedis; static { jedis = pool.getResource(); } private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { list(request, response); try { response.sendRedirect("list.jsp"); } catch (IOException e) { e.printStackTrace(); } } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } private void list(HttpServletRequest request, HttpServletResponse response) { Set set = jedis.smembers("userIdSet"); Iterator ite = set.iterator(); System.out.println("中标名单-------------------------"); int i = 0; Map<String, String> map = new HashMap<String, String>(); while (ite.hasNext()) { i++; Object obj1 = ite.next(); System.out.println("第" + i + "名：" + obj1); map.put("第" + i + "名：", obj1 + ""); } request.getSession().setAttribute("user", map); System.out.println("中标名单-------------------------"); } }
工具类
package com.commnon;
import java.util.ResourceBundle; import redis.clients.jedis.Jedis; import redis.clients.jedis.JedisPool; import redis.clients.jedis.JedisPoolConfig; /** * Redis操作接口 * * @author 林计钦 * @version 1.0 2013-6-14 上午08:54:14 */ public class RedisAPI { private static JedisPool pool = null; private static ThreadLocal<JedisPool> poolThreadLocal = new ThreadLocal<JedisPool>(); /** * 构建redis连接池 * * @param ip * @param port * @return JedisPool */ public static JedisPool getPool() { if (pool == null) { ResourceBundle bundle = ResourceBundle.getBundle("redis"); if (bundle == null) { throw new IllegalArgumentException( "[redis.properties] is not found!"); } JedisPoolConfig config = new JedisPoolConfig(); config.setMaxActive(Integer.valueOf(bundle .getString("redis.pool.maxActive"))); config.setMaxIdle(Integer.valueOf(bundle .getString("redis.pool.maxIdle"))); config.setMaxWait(Long.valueOf(bundle.getString("redis.pool.maxWait"))); config.setTestOnBorrow(Boolean.valueOf(bundle .getString("redis.pool.testOnBorrow"))); config.setTestOnReturn(Boolean.valueOf(bundle .getString("redis.pool.testOnReturn"))); pool = new JedisPool(config, bundle.getString("redis.ip"), Integer.valueOf(bundle.getString("redis.port"))); } return pool; } public static JedisPool getConnection() { // ②如果poolThreadLocal没有本线程对应的JedisPool创建一个新的JedisPool，将其保存到线程本地变量中。 if (poolThreadLocal.get() == null) { pool = RedisAPI.getPool(); poolThreadLocal.set(pool); return pool; } else { return poolThreadLocal.get();// ③直接返回线程本地变量 } } /** * 返还到连接池 * * @param pool * @param redis */ public static void returnResource(JedisPool pool, Jedis redis) { if (redis != null) { pool.returnResource(redis); } } /** * 获取数据 * * @param key * @return */ public static String get(String key) { String value = null; JedisPool pool = null; Jedis jedis = null; try { pool = getPool(); jedis = pool.getResource(); value = jedis.get(key); } catch (Exception e) { e.printStackTrace(); } finally { // 释放redis对象 pool.returnBrokenResource(jedis); // 返还到连接池 returnResource(pool, jedis); } return value; } /** * 赋值数据 * * @param key * @return */ public static String set(String key, String value) { String result = null; JedisPool pool = null; Jedis jedis = null; try { pool = getPool(); jedis = pool.getResource(); result = jedis.set(key, value); } catch (Exception e) { e.printStackTrace(); } finally { // 释放redis对象 pool.returnBrokenResource(jedis); // 返还到连接池 returnResource(pool, jedis); } return result; } /** * 赋值数据 * * @param key * @return */ public static Long sadd(String key, String value) { Long result = null; JedisPool pool = null; Jedis jedis = null; try { pool = getPool(); jedis = pool.getResource(); result = jedis.sadd(key, value); } catch (Exception e) { e.printStackTrace(); } finally { // 释放redis对象 pool.returnBrokenResource(jedis); // 返还到连接池 returnResource(pool, jedis); } return result; } /** * 判断set中是否有值 * * @param key * @return */ public static Boolean sismember(String key, String member) { Boolean result = null; JedisPool pool = null; Jedis jedis = null; try { pool = getPool(); jedis = pool.getResource(); result = jedis.sismember(key, member); } catch (Exception e) { e.printStackTrace(); } finally { // 释放redis对象 pool.returnBrokenResource(jedis); // 返还到连接池 returnResource(pool, jedis); } return result; } }
redis.properties
#\u6700\u5927\u5206\u914d\u7684\u5bf9\u8c61\u6570
redis.pool.maxActive=1024
#\u6700\u5927\u80fd\u591f\u4fdd\u6301idel\u72b6\u6001\u7684\u5bf9\u8c61\u6570
redis.pool.maxIdle=200
#\u5f53\u6c60\u5185\u6ca1\u6709\u8fd4\u56de\u5bf9\u8c61\u65f6\uff0c\u6700\u5927\u7b49\u5f85\u65f6\u95f4
redis.pool.maxWait=1000
#\u5f53\u8c03\u7528borrow Object\u65b9\u6cd5\u65f6\uff0c\u662f\u5426\u8fdb\u884c\u6709\u6548\u6027\u68c0\u67e5
redis.pool.testOnBorrow=true
#\u5f53\u8c03\u7528return Object\u65b9\u6cd5\u65f6\uff0c\u662f\u5426\u8fdb\u884c\u6709\u6548\u6027\u68c0\u67e5
redis.pool.testOnReturn=true
#IP
redis.ip=127.0.0.1
#Port
redis.port=6379
bid.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>抢标秒杀</title>
<style type="text/css">
* { margin: 0; } html, body { height: 100%; } .wrapper { min-height: 100%; height: auto !important; height: 100%; margin: 0 auto -155px; } .footer, .push { height: 155px; } .middle { text-align: center; margin: 0 auto; width: 600px; height: auto; } </style> </head> <body> <form name="formBid" action="bid" method="get"> <div class="wrapper"> <div class="middle"> <h1 style="padding: 0px 0 10px;">秒标</h1> <br> <br> <br> <br> <br> <br> <br><br> <br> <br> <input type="submit"style="width: 600px; height: 200px" value="秒杀" /> <br> <br><br> <br> <br></div></div></form><form name="formList" action="list" method="post"><div class="wrapper"><div class="middle"><br> <br> <br> <br> <br> <inputtype="submit" style="width: 200px; height: 50px" value="查看秒杀结果" /></div></div></form></body></html>
list.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>抢标秒杀</title>
<style type="text/css">
* { margin: 0; } html, body { height: 100%; } .wrapper { min-height: 100%; height: auto !important; height: 100%; margin: 0 auto -155px; } .footer, .push { height: 155px; } .middle { text-align: center; margin: 0 auto; width: 600px; height: auto; } </style> </head> <body> <% java.util.Map<String, String> mapBean = (java.util.Map<String, String>) request.getSession() .getAttribute("user"); %> <form name="formList" action="list" method="post"> <div class="wrapper"> <div class="middle"> <br> <br> <br> <br> <br> <br> <br> <br> <h1 style="padding: 0px 0 10px;"> 中奖名单<%if (mapBean != null) { %><%=mapBean.size()%></h1><% } %><br><%if (mapBean != null) { for (String key : mapBean.keySet()) { %><%=key%>--<%=mapBean.get(key)%><br><% } } %></div></div></form></body></html>