一、代码实现
1.引入依赖
<dependency>
<groupId>org.redisson</groupId>
<artifactId>redisson</artifactId>
<version>3.8.2</version>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.redisson</groupId>
<artifactId>redisson-spring-boot-starter</artifactId>
<version>3.8.2</version>
</dependency>
2.创建一个 redisson-config.yml 文件
#Redisson配置
singleServerConfig:
address: "redis://127.0.0.1:6379"
password: xxxx
clientName: null
database: 7 #选择使用哪个数据库0~15
idleConnectionTimeout: 10000
pingTimeout: 1000
connectTimeout: 10000
timeout: 3000
retryAttempts: 3
retryInterval: 1500
reconnectionTimeout: 3000
failedAttempts: 3
subscriptionsPerConnection: 5
subscriptionConnectionMinimumIdleSize: 1
subscriptionConnectionPoolSize: 50
connectionMinimumIdleSize: 32
connectionPoolSize: 64
dnsMonitoringInterval: 5000
#dnsMonitoring: false
threads: 0
nettyThreads: 0
codec:
class: "org.redisson.codec.JsonJacksonCodec"
transportMode: "NIO"
3.创建配置类 RedissonConfig 用于读取配置文件
/**
* 添加Redisson的配置参数读取类RedissonConfig
*/
@Configuration
public class RedissonConfig {
@Bean
public RedissonClient redisson() throws IOException {
// 本例子使用的是yaml格式的配置文件，读取使用Config.fromYAML，如果是Json文件，则使用Config.fromJSON
Config config = Config.fromYAML(RedissonConfig.class.getClassLoader().getResource("redisson-config.yml"));
return Redisson.create(config);
}
}
4.创建工具类 DistributedRedisLock
@Component
public class DistributedRedisLock {
@Autowired
private RedissonClient redissonClient;
private static final String LOCK_TITLE = "redisLock_";
//加锁
public boolean acquire(String lockName){
//声明key对象
String key = LOCK_TITLE + lockName;
System.out.println(key);
//获取锁对象
RLock mylock = redissonClient.getLock(key);
//加锁，并且设置锁过期时间，防止死锁的产生
mylock.lock(2, TimeUnit.MINUTES);
System.err.println("======lock======"+Thread.currentThread().getName());
//加锁成功
return true;
}
//锁的释放
public void release(String lockName){
//必须是和加锁时的同一个key
String key = LOCK_TITLE + lockName;
//获取所对象
RLock mylock = redissonClient.getLock(key);
//释放锁（解锁）
mylock.unlock();
System.err.println("======unlock======"+Thread.currentThread().getName());
}
}
5.调用工具类中的方法使用锁（id为一个参数，比如下订单，就可以用订单id）
//加锁
distributedRedisLock.acquire(id);
//业务逻辑
//释放锁
distributedRedisLock.release(id);
二、原理
微信图片编辑_20210804163920.jpg
底层代码实现
<T> RFuture<T> tryLockInnerAsync(long leaseTime, TimeUnit unit, long threadId, RedisStrictCommand<T> command) {
this.internalLockLeaseTime = unit.toMillis(leaseTime);
return this.commandExecutor.evalWriteAsync(this.getName(), LongCodec.INSTANCE, command,
"if (redis.call('exists', KEYS[1]) == 0) then redis.call('hset', KEYS[1], ARGV[2], 1);
redis.call('pexpire', KEYS[1], ARGV[1]); return nil; end; if (redis.call('hexists',
KEYS[1], ARGV[2]) == 1) then redis.call('hincrby', KEYS[1], ARGV[2], 1);
redis.call('pexpire', KEYS[1], ARGV[1]);
return nil; end; return redis.call('pttl',
KEYS[1]);", Collections.singletonList(this.getName()), new Object[]{this.internalLockLeaseTime, this.getLockName(threadId)});
}
由redis的Lua脚本实现
