springboot使用redission实现基于redis的分布式锁
目前大多数互联网公司都是采用分布式架构部署系统，分布式场景中的数据一致性问题一直是非常重要的问题，分布式的CAP理论告诉我们任何一个分布式系统无法同时满足一致性（consistency）可用性（avaliability）分区容错性（partition tolerance）,最多只能满足其中两项。在互联网领域往往会牺牲一致性来换取高可用性，系统只保证最终数据一致性，只要这个最终时间是用户可以接受的范围内。
基于分布式架构实现数据一致性的方法有三种
1基于数据库实现的分布式锁
2基于缓存（redis）实现分布式锁
3基于zookeeper实现分布式锁
本文将基于redis实现分布式锁
我们使用第三方库redission来实现对redis的操作，
maven引入redission如下
<dependency>
<groupId>org.redisson</groupId>
<artifactId>redisson</artifactId>
<version>3.11.4</version>
</dependency>
Redission工具类RedissLockUtil
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import java.util.concurrent.TimeUnit;
public class RedissLockUtil {
private static RedissonClient redissonClient;
public void setRedissonClient(RedissonClient locker) {
redissonClient = locker;
}
/**
* 加锁
* @param lockKey
* @return
*/
public static RLock lock(String lockKey) {
RLock lock = redissonClient.getLock(lockKey);
lock.lock();
return lock;
}
/**
* 释放锁
* @param lockKey
*/
public static void unlock(String lockKey) {
RLock lock = redissonClient.getLock(lockKey);
lock.unlock();
}
/**
* 释放锁
* @param lock
*/
public static void unlock(RLock lock) {
lock.unlock();
}
/**
* 带超时的锁
* @param lockKey
* @param timeout 超时时间 单位：秒
*/
public static RLock lock(String lockKey, int timeout) {
RLock lock = redissonClient.getLock(lockKey);
lock.lock(timeout, TimeUnit.SECONDS);
return lock;
}
/**
* 带超时的锁
* @param lockKey
* @param unit 时间单位
* @param timeout 超时时间
*/
public static RLock lock(String lockKey, TimeUnit unit ,int timeout) {
RLock lock = redissonClient.getLock(lockKey);
lock.lock(timeout, unit);
return lock;
}
/**
* 尝试获取锁
* @param lockKey
* @param waitTime 最多等待时间
* @param leaseTime 上锁后自动释放锁时间
* @return
*/
public static boolean tryLock(String lockKey, int waitTime, int leaseTime) {
RLock lock = redissonClient.getLock(lockKey);
try {
return lock.tryLock(waitTime, leaseTime, TimeUnit.SECONDS);
} catch (InterruptedException e) {
return false;
}
}
/**
* 尝试获取锁
* @param lockKey
* @param unit 时间单位
* @param waitTime 最多等待时间
* @param leaseTime 上锁后自动释放锁时间
* @return
*/
public static boolean tryLock(String lockKey, TimeUnit unit, int waitTime, int leaseTime) {
RLock lock = redissonClient.getLock(lockKey);
try {
return lock.tryLock(waitTime, leaseTime, unit);
} catch (InterruptedException e) {
return false;
}
}
}
redisson属性装配类RedissonProperties，读取配置文件中的redission配置信息
import org.springframework.boot.context.properties.ConfigurationProperties;
@ConditionalOnProperty("redisson.password")
@ConfigurationProperties(prefix = "redisson")
public class RedissonProperties {
private int timeout = 3000;
private String address;
private String password;
private int connectionPoolSize = 64;
private int connectionMinimumIdleSize=10;
private int slaveConnectionPoolSize = 250;
private int masterConnectionPoolSize = 250;
private String[] sentinelAddresses;
private String masterName;
public int getTimeout() {
return timeout;
}
public void setTimeout(int timeout) {
this.timeout = timeout;
}
public int getSlaveConnectionPoolSize() {
return slaveConnectionPoolSize;
}
public void setSlaveConnectionPoolSize(int slaveConnectionPoolSize) {
this.slaveConnectionPoolSize = slaveConnectionPoolSize;
}
public int getMasterConnectionPoolSize() {
return masterConnectionPoolSize;
}
public void setMasterConnectionPoolSize(int masterConnectionPoolSize) {
this.masterConnectionPoolSize = masterConnectionPoolSize;
}
public String[] getSentinelAddresses() {
return sentinelAddresses;
}
public void setSentinelAddresses(String sentinelAddresses) {
this.sentinelAddresses = sentinelAddresses.split(",");
}
public String getMasterName() {
return masterName;
}
public void setMasterName(String masterName) {
this.masterName = masterName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public int getConnectionPoolSize() {
return connectionPoolSize;
}
public void setConnectionPoolSize(int connectionPoolSize) {
this.connectionPoolSize = connectionPoolSize;
}
public int getConnectionMinimumIdleSize() {
return connectionMinimumIdleSize;
}
public void setConnectionMinimumIdleSize(int connectionMinimumIdleSize) {
this.connectionMinimumIdleSize = connectionMinimumIdleSize;
}
}
对应的application.properties配置文件内容
# redisson lock
redisson.address=redis://127.0.0.1:6379
redisson.password=123456
redission的自动装配类RedissonAutoConfiguration
import org.apache.commons.lang3.StringUtils;
import org.redisson.Redisson;
import org.redisson.api.RedissonClient;
import org.redisson.config.Config;
import org.redisson.config.SingleServerConfig;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
@ConditionalOnClass(Config.class)
@EnableConfigurationProperties(RedissonProperties.class)
public class RedissonAutoConfiguration {
@Autowired
private RedissonProperties redssionProperties;
/**
* 哨兵模式自动装配
* @return
*/
// @Bean
// @ConditionalOnProperty(name="redisson.master-name")
// RedissonClient redissonSentinel() {
// Config config = new Config();
// SentinelServersConfig serverConfig = config.useSentinelServers().addSentinelAddress(redssionProperties.getSentinelAddresses())
// .setMasterName(redssionProperties.getMasterName())
// .setTimeout(redssionProperties.getTimeout())
// .setMasterConnectionPoolSize(redssionProperties.getMasterConnectionPoolSize())
// .setSlaveConnectionPoolSize(redssionProperties.getSlaveConnectionPoolSize());
//
// if(StringUtils.isNotBlank(redssionProperties.getPassword())) {
// serverConfig.setPassword(redssionProperties.getPassword());
// }
// return Redisson.create(config);
// }
/**
* 单机模式自动装配
* @return
*/
@Bean
@ConditionalOnProperty(name="redisson.address")
RedissonClient redissonSingle() {
Config config = new Config();
SingleServerConfig serverConfig = config.useSingleServer()
.setAddress(redssionProperties.getAddress())
.setTimeout(redssionProperties.getTimeout())
.setConnectionPoolSize(redssionProperties.getConnectionPoolSize())
.setConnectionMinimumIdleSize(redssionProperties.getConnectionMinimumIdleSize());
if(StringUtils.isNotBlank(redssionProperties.getPassword())) {
serverConfig.setPassword(redssionProperties.getPassword());
}
return Redisson.create(config);
}
/**
* 装配locker类，并将实例注入到RedissLockUtil中
* @return
*/
@Bean
RedissLockUtil redissLockUtil(RedissonClient redissonClient) {
RedissLockUtil redissLockUtil = new RedissLockUtil();
redissLockUtil.setRedissonClient(redissonClient);
return redissLockUtil;
}
}
springboot的service实现部分内容
@Transactional
public Result startSeckilRedisLock(long seckillId,long userId) {
boolean res=false;
try {
/**
* 尝试获取锁，最多等待3秒，上锁以后20秒自动解锁（实际项目中推荐这种，以防出现死锁）、这里根据预估秒杀人数，设定自动释放锁时间.
* 这种实现也存在问题，事物和锁会有冲突，建议AOP实现。
*/
res = RedissLockUtil.tryLock(seckillId+"", TimeUnit.SECONDS, 3, 20);
if(res){
String nativeSql = "SELECT number FROM seckill WHERE seckill_id=?";
Object object = dynamicQuery.nativeQueryObject(nativeSql, new Object[]{seckillId});
Long number = ((Number) object).longValue();
if(number>0){
SuccessKilled killed = new SuccessKilled();
killed.setSeckillId(seckillId);
killed.setUserId(userId);
killed.setState((short)0);
killed.setCreateTime(new Timestamp(new Date().getTime()));
dynamicQuery.save(killed);
nativeSql = "UPDATE seckill SET number=number-1 WHERE seckill_id=? AND number>0";
dynamicQuery.nativeExecuteUpdate(nativeSql, new Object[]{seckillId});
}else{
return Result.error(SeckillStatEnum.END);
}
}else{
return Result.error(SeckillStatEnum.MUCH);
}
} catch (Exception e) {
e.printStackTrace();
} finally{
if(res){//释放锁
RedissLockUtil.unlock(seckillId+"");
}
}
return Result.ok(SeckillStatEnum.SUCCESS);
}
参考链接：https://blog.52itstyle.vip/