最强分布式锁工具：Redisson（一）

// 加锁
public Boolean tryLock(String key, String value, long timeout, TimeUnit unit) {
    return redisTemplate.opsForValue().setIfAbsent(key, value, timeout, unit);
}
// 解锁，防止删错别人的锁，以uuid为value校验是否自己的锁
public void unlock(String lockName, String uuid) {
    if(uuid.equals(redisTemplate.opsForValue().get(lockName)){        redisTemplate.opsForValue().del(lockName);    }
}
// 结构
if(tryLock){
    // todo
}finally{
    unlock;
}

if redis.call('get', KEYS[1]) == ARGV[1] 
    then 
 -- 执行删除操作
        return redis.call('del', KEYS[1]) 
    else 
 -- 不成功，返回0
        return 0 
end

// 解锁脚本
DefaultRedisScript<Object> unlockScript = new DefaultRedisScript();
unlockScript.setScriptSource(new ResourceScriptSource(new ClassPathResource("lockDel.lua")));
// 执行lua脚本解锁
redisTemplate.execute(unlockScript, Collections.singletonList(keyName), value);

hset lockname1 threadId 1

hget lockname1 threadId

lockname 锁名称
    key1：   threadId   唯一键，线程id
    value1：  count     计数器，记录该线程获取锁的次数

local key = KEYS[1];
local threadId = ARGV[1];
local releaseTime = ARGV[2];
-- lockname不存在
if(redis.call('exists', key) == 0) then
    redis.call('hset', key, threadId, '1');
    redis.call('expire', key, releaseTime);
    return 1;
end;
-- 当前线程已id存在
if(redis.call('hexists', key, threadId) == 1) then
    redis.call('hincrby', key, threadId, '1');
    redis.call('expire', key, releaseTime);
    return 1;
end;
return 0;

local key = KEYS[1];
local threadId = ARGV[1];
-- lockname、threadId不存在
if (redis.call('hexists', key, threadId) == 0) then
    return nil;
end;
-- 计数器-1
local count = redis.call('hincrby', key, threadId, -1);
-- 删除lock
if (count == 0) then
    redis.call('del', key);
    return nil;
end;

/**
 * @description 原生redis实现分布式锁
 **/
@Getter
@Setter
public class RedisLock {
    private RedisTemplate redisTemplate;
    private DefaultRedisScript<Long> lockScript;
    private DefaultRedisScript<Object> unlockScript;
    public RedisLock(RedisTemplate redisTemplate) {
        this.redisTemplate = redisTemplate;
        // 加载加锁的脚本
        lockScript = new DefaultRedisScript<>();
        this.lockScript.setScriptSource(new ResourceScriptSource(new ClassPathResource("lock.lua")));
        this.lockScript.setResultType(Long.class);
        // 加载释放锁的脚本
        unlockScript = new DefaultRedisScript<>();
        this.unlockScript.setScriptSource(new ResourceScriptSource(new ClassPathResource("unlock.lua")));
    }
    /**
     * 获取锁
     */
    public String tryLock(String lockName, long releaseTime) {
        // 存入的线程信息的前缀
        String key = UUID.randomUUID().toString();
        // 执行脚本
        Long result = (Long) redisTemplate.execute(
                lockScript,
                Collections.singletonList(lockName),
                key + Thread.currentThread().getId(),
                releaseTime);
        if (result != null && result.intValue() == 1) {
            return key;
        } else {
            return null;
        }
    }
    /**
     * 解锁
     * @param lockName
     * @param key
     */
    public void unlock(String lockName, String key) {
        redisTemplate.execute(unlockScript,
                Collections.singletonList(lockName),
                key + Thread.currentThread().getId()
                );
    }
}

<!-- 原生，本章使用-->
<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson</artifactId>
    <version>3.13.6</version>
</dependency>
<!-- 另一种Spring集成starter，本章未使用 -->
<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson-spring-boot-starter</artifactId>
    <version>3.13.6</version>
</dependency>

@Configuration
public class RedissionConfig {
    @Value("${spring.redis.host}")
    private String redisHost;
    @Value("${spring.redis.password}")
    private String password;
    private int port = 6379;
    @Bean
    public RedissonClient getRedisson() {
        Config config = new Config();
        config.useSingleServer().
                setAddress("redis://" + redisHost + ":" + port).
                setPassword(password);
        config.setCodec(new JsonJacksonCodec());
        return Redisson.create(config);
    }
}

@Resource
private RedissonClient redissonClient;
RLock rLock = redissonClient.getLock(lockName);
try {
    boolean isLocked = rLock.tryLock(expireTime, TimeUnit.MILLISECONDS);
    if (isLocked) {
        // TODO
                }
    } catch (Exception e) {
            rLock.unlock();
    }