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在分布式系统中，常常会出现须要竞争同一资源的情况，本代码基于redis3.0.1+jedis2.7.1实现了分布式锁。
redis集群的搭建，请见我的另外一篇文章：<>《redis3.0.1集群环境搭建》
可用于比如秒杀系统中的商品库存的管理。付完整代码及測试用例。
package com.gaojiasoft.gaojiaRedis; import java.util.UUID;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit; import javax.annotation.PostConstruct; import org.apache.commons.lang3.RandomUtils;
import org.apache.commons.lang3.concurrent.BasicThreadFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired; import redis.clients.jedis.JedisCluster;
import redis.clients.jedis.exceptions.JedisConnectionException; /**
* 分布式锁管理器，支持对单个资源加锁解锁。或给一批资源的批量加锁及解锁
* @ClassName: DistributedLockManger
* @Description:
* @author 何志雄 001
* @company 南京高嘉软件技术有限公司
* @date 2015年6月3日 下午5:44:06
*/
public class DistributedLockManger
{ private static final Logger LOGGER = LoggerFactory.getLogger(DistributedLockManger.class); private static final int DEFAULT_SINGLE_EXPIRE_TIME = 3; // private static final int DEFAULT_BATCH_EXPIRE_TIME = 6; //static的变量无法注解
@Autowired
JedisCluster jc; private static DistributedLockManger lockManger; public DistributedLockManger()
{
} @PostConstruct
public void init()
{
lockManger = this;
lockManger.jc = this.jc;
} /**
* 获取锁 假设锁可用 马上返回true。 否则马上返回false，作为非堵塞式锁使用
* @param key
* @param value
* @return
*/
public static boolean tryLock(String key , String value)
{
try
{
return tryLock(key, value, 0L, null);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
return false;
} /**
* 锁在给定的等待时间内空暇，则获取锁成功 返回true， 否则返回false。作为堵塞式锁使用
* @param key 锁键
* @param value 被谁锁定
* @param timeout 尝试获取锁时长。建议传递500,结合实践单位。则可表示500毫秒
* @param unit。建议传递TimeUnit.MILLISECONDS
* @return
* @throws InterruptedException
*/
public static boolean tryLock(String key , String value , long timeout , TimeUnit unit) throws InterruptedException
{
//纳秒
long begin = System.nanoTime();
do
{
//LOGGER.debug("{}尝试获得{}的锁.", value, key);
Long i = lockManger.jc.setnx(key, value);
if (i == 1)
{
lockManger.jc.expire(key, DEFAULT_SINGLE_EXPIRE_TIME);
LOGGER.debug("{}成功获取{}的锁,设置锁过期时间为{}秒 ", value, key, DEFAULT_SINGLE_EXPIRE_TIME);
return true;
}
else
{
// 存在锁 ，但可能获取不到，原因是获取的一刹那间
// String desc = lockManger.jc.get(key);
// LOGGER.error("{}正被{}锁定.", key, desc);
}
if (timeout == 0)
{
break;
}
//在其睡眠的期间，锁可能被解，也可能又被他人占用，但会尝试继续获取锁直到指定的时间
Thread.sleep(100);
}
while ((System.nanoTime() - begin) < unit.toNanos(timeout));
//因超时没有获得锁
return false;
} /**
* 释放单个锁
* @param key 锁键
* @param value 被谁释放
*/
public static void unLock(String key , String value)
{
try
{
lockManger.jc.del(key);
LOGGER.debug("{}锁被{}释放 .", key, value);
}
catch (JedisConnectionException je)
{ }
catch (Exception e)
{ }
} public void test() throws InterruptedException
{
String productId = "18061249844";
String userId;
for (int i = 1; i <= 500; i++)
{
//随机产生一个用户
userId = UUID.randomUUID().toString();
//该用户试图锁定(假设被锁，尝试等待300毫秒)。在处理一些事情后。再释放锁
testLock(productId, userId);
Thread.sleep(20);
}
} private static final ThreadPoolExecutor executor = new ThreadPoolExecutor(150, 150, 30L, TimeUnit.SECONDS,
new LinkedBlockingQueue<Runnable>(), new BasicThreadFactory.Builder().daemon(true)
.namingPattern("mongo-oper-%d").build(), new ThreadPoolExecutor.CallerRunsPolicy()); private static void testLock(final String key , final String value)
{
executor.execute(new Runnable()
{
@Override
public void run()
{
try
{
//获取锁，假设不能马上获取，尝试等待1000毫秒
boolean isLock = DistributedLockManger.tryLock(key, value, 500, TimeUnit.MILLISECONDS);
if (isLock)
{
//doSomething(占用锁20毫秒到4秒，模拟处理事务)
long doSomeThingTime = RandomUtils.nextLong(20, 4000);
LOGGER.debug("{}将持有锁{}时长{}毫秒.", value, key, doSomeThingTime);
Thread.sleep(doSomeThingTime);
//然后释放锁
DistributedLockManger.unLock(key, value);
}
}
catch (Throwable th)
{
}
}
});
} public JedisCluster getJc()
{
return jc;
} public void setJc(JedisCluster jc)
{
this.jc = jc;
}
}
Spring配置：
redis.properties
#最大闲置连接数
im.hs.server.redis.maxIdle=500
#最大连接数，超过此连接时操作redis会报错
im.hs.server.redis.maxTotal=5000
im.hs.server.redis.maxWaitTime=1000
im.hs.server.redis.testOnBorrow=true
#最小闲置连接数，spring启动的时候自己主动建立该数目的连接供应用程序使用，不够的时候会申请。
im.hs.server.redis.minIdle=300
spring-redis.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <context:property-placeholder location="classpath:conf/redis/redis.properties" /> <!-- 其实，仅仅须要连接1个节点就能够 -->
<bean id="culster7001" class="redis.clients.jedis.HostAndPort">
<constructor-arg name="host" value="192.168.62.153" />
<constructor-arg name="port" value="7001" />
</bean>
<bean id="culster7002" class="redis.clients.jedis.HostAndPort">
<constructor-arg name="host" value="192.168.62.153" />
<constructor-arg name="port" value="7002" />
</bean>
<bean id="culster7003" class="redis.clients.jedis.HostAndPort">
<constructor-arg name="host" value="192.168.62.154" />
<constructor-arg name="port" value="7003" />
</bean>
<bean id="culster7004" class="redis.clients.jedis.HostAndPort">
<constructor-arg name="host" value="192.168.62.154" />
<constructor-arg name="port" value="7004" />
</bean>
<bean id="culster7005" class="redis.clients.jedis.HostAndPort">
<constructor-arg name="host" value="192.168.62.155" />
<constructor-arg name="port" value="7005" />
</bean>
<bean id="culster7006" class="redis.clients.jedis.HostAndPort">
<constructor-arg name="host" value="192.168.62.155" />
<constructor-arg name="port" value="7006" />
</bean>
<bean id="culster7007" class="redis.clients.jedis.HostAndPort">
<constructor-arg name="host" value="192.168.62.152" />
<constructor-arg name="port" value="7007" />
</bean>
<bean id="culster7008" class="redis.clients.jedis.HostAndPort">
<constructor-arg name="host" value="192.168.62.152" />
<constructor-arg name="port" value="7008" />
</bean>
<bean id="poolConfig" class="redis.clients.jedis.JedisPoolConfig">
<property name="maxTotal" value="${im.hs.server.redis.maxTotal}" />
<property name="minIdle" value="${im.hs.server.redis.minIdle}" />
<property name="maxWaitMillis" value="${im.hs.server.redis.maxWaitTime}" />
<property name="maxIdle" value="${im.hs.server.redis.maxIdle}" />
<property name="testOnBorrow" value="${im.hs.server.redis.testOnBorrow}" />
<property name="testOnReturn" value="true" />
<property name="testWhileIdle" value="true" />
</bean> <bean id="jc" class="redis.clients.jedis.JedisCluster">
<constructor-arg name="nodes">
<set>
<ref bean="culster7001" />
<ref bean="culster7002" />
<ref bean="culster7003" />
<ref bean="culster7004" />
<ref bean="culster7005" />
<ref bean="culster7006" />
<ref bean="culster7007" />
<ref bean="culster7008" />
</set>
</constructor-arg>
<constructor-arg name="poolConfig"> <ref bean="poolConfig" /> </constructor-arg>
</bean> <bean id="distributedLock" class="com.gaojiasoft.gaojiaRedis.DistributedLockManger" /> <context:annotation-config />
</beans>
測试代码：
package com.gaojiasoft.gaojiaRedis; import java.util.UUID;
import java.util.concurrent.TimeUnit; import junit.framework.TestCase; import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; public class ClusterJedisTester extends TestCase
{
private Logger logger = LoggerFactory.getLogger(ClusterJedisTester.class); private static String[] list = new String[] { "classpath:conf/redis/spring-redis.xml" }; private static ConfigurableApplicationContext context = new ClassPathXmlApplicationContext(list, true, null); DistributedLockManger distributedLock = (DistributedLockManger)context.getBean("distributedLock"); @Test
public void testLock() throws InterruptedException
{
distributedLock.test();
while(true)
{
Thread.sleep(1000);
}
}
}
