Springboot整合Redisson 锁

前言

Redisson是一个在Redis的基础上实现的Java驻内存数据网格

一、依赖

  <dependency>
      <groupId>org.redisson</groupId>
      <artifactId>redisson</artifactId>
      <version>3.15.4</version>
  </dependency>

二、配置文件

spring:
  redis:
    database: 7
    host: 116.62.178.11
    port: 6379
    password: 1234qwer
    #  spring-boot 1.0默认 jedis;  spring-boot2.0 默认lettuce ，lettuce线程安全
    lettuce:
      pool:
        # 连接池中的最大空闲连接 默认8
        max-idle: 8
        # 连接池中的最小空闲连接 默认0
        min-idle: 500
        # 连接池最大连接数 默认8 ，负数表示没有限制
        max-active: 2000
        # 连接池最大阻塞等待时间（使用负值表示没有限制） 默认-1
        max-wait: -1
    cache:
      type: redis

@Configuration
public class RedissonConfig {

    @Value("${spring.redis.host}")
    private String host;
    @Value("${spring.redis.port}")
    private int port;
    @Value("${spring.redis.password}")
    private String password;

    @Bean(destroyMethod = "shutdown")
    RedissonClient redissonClient() throws IOException {
        Config config = new Config();
        config.useSingleServer()
                .setPassword(password)
                .setAddress("redis://" + host + ":" + port).setDatabase(7);
        return Redisson.create(config);
    }
}

三、锁的使用

读写锁

public class RedissionDemo {

    @Autowired
    private RedissonClient redissonClient;
    @Autowired
    private RedisTemplate redisTemplate;

    /**
     * 读写锁 总结
     *
     * 读锁又叫共享锁
     * 写锁又叫排他锁（互斥锁）
     * 读 + 读 相当于无锁，并发读，同时加锁成功
     * 写 + 写 阻塞状态
     * 写 + 读 等待写锁释放
     * 读 + 写 等待读锁完，才写，
     */
    public String writeValue() {
        String str = "";
        RReadWriteLock readWriteLock = redissonClient.getReadWriteLock("writeLock");
        RLock rLock = readWriteLock.writeLock();
        try {
            rLock.lock();
            str = UUID.randomUUID().toString();
            redisTemplate.opsForValue().set("uuid", str);
            Thread.sleep(30000);
        } catch (Exception e) {

        } finally {
            rLock.unlock();
        }
        return str;
    }

    /**
     * 读锁
     *
     * @return
     */
    public String readValue() {
        String str = "";
        RReadWriteLock readWriteLock = redissonClient.getReadWriteLock("writeLock");
        RLock rLock = readWriteLock.readLock();
        rLock.lock();
        str = (String) redisTemplate.opsForValue().get("uuid");
        rLock.unlock();
        return str;
    }
 
}

信号量

public class RedissionDemo {

    @Autowired
    private RedissonClient redissonClient;
    @Autowired
    private RedisTemplate redisTemplate;
    /**
     * 信号量
     *
     * @return
     */
    //停车方法
    @GetMapping("/park")
    public String park() throws InterruptedException {
        //这里是获取信号量的值，这个信号量的name一定要与你初始化的一致
        RSemaphore park = redissonClient.getSemaphore("park");
        //这里会将信号量里面的值-1，如果为0则一直等待，直到信号量>0
        park.acquire();
        //tryAcquire为非阻塞式等待
        //park.tryAcquire();
        return "ok";
    }
    public String go() throws InterruptedException {
        //这里是获取信号量的值，这个信号量的name一定要与你初始化的一致
        RSemaphore park = redissonClient.getSemaphore("park");
        //这里会将信号量里面的值+1，也就是释放信号量
        park.release();
        return "ok";
    }
}

闭锁

public class RedissionDemo {

    @Autowired
    private RedissonClient redissonClient;
    @Autowired
    private RedisTemplate redisTemplate;
 
    /**
     * 闭锁，限流
     *
     * @return
     * @throws InterruptedException
     */
    //锁门
    public String lockdoor() throws InterruptedException {
        RCountDownLatch door = redissonClient.getCountDownLatch("door");
        //设置一个班级有20个同学
        door.trySetCount(20);
        //需要等到20个同学全部离开，才锁门
        door.await();
        return "锁门了";
    }

    public String leave(Long id) throws InterruptedException {
        RCountDownLatch door = redissonClient.getCountDownLatch("door");
        //表示一个同学离开
        door.countDown();
        return "" + id + "号同学离开了";
    }
}

四、分布式秒杀

秒杀流程：

@Service
@Slf4j
public class DistributedSecKillBiz {

    @Autowired
    private RedisTemplate redisTemplate;

    @Autowired
    private RedissonClient redissonClient;
 

    /**
     * 分布式锁。唯一缺点 枷锁失效时间
     * 枷锁院子操作，
     * 解锁，删除锁也是原子操作 瑕疵没有续命
     *
     * @return
     */
    public String doKill() {
        String lock = UUID.randomUUID().toString();
        String goodsId = "10054";
        boolean flag = redisTemplate.opsForValue().setIfAbsent(goodsId, lock, 30, TimeUnit.SECONDS);
        if (flag) {
            // 获取锁成功
            try {
                Long stock = redisTemplate.opsForValue().decrement(upActivityKey() + SecKillConstant.CACHE_FOODS_COUNT + goodsId);
                if (stock > 0) {
                    redisTemplate.opsForValue().increment(upActivityKey() + SecKillConstant.CACHE_FOODS_COUNT + goodsId);
                    log.info("扣减库存成功，还剩:" + stock);
                }
                return "库存不足，该商品已抢购完！";
            } catch (Exception e) {

            } finally {
                String script = "if redis.call('get',KEYS[1]) == ARGV[1] then return redis.call('del',KEYS[1]) else return 0 end";
                redisTemplate.execute(new DefaultRedisScript<>(script, Long.class), Arrays.asList(goodsId), lock);
            }
        }
        return doKill();
    }


    /**
     * 整合 redission
     * @return
     */
    public String doKillDistributed() {
        String goodsId = "10054";
        RLock lock = redissonClient.getLock(upActivityKey() + SecKillConstant.LOCK + goodsId);
        // 获取锁成功
        try {
            //1 阻塞式等待，默认30秒时间
            //2 自动续期，如果业务超长，续上新的30秒，不用担心过期时间，锁自动删除掉
            //3 枷锁的业务运行完成，就不会给当前的锁自动续期，即使没有手动释放锁也会，30秒自动释放
//            lock.lock(30, TimeUnit.SECONDS); //不会自动续期需要注意
            lock.lock();
            Long stock = redisTemplate.opsForValue().decrement(upActivityKey() + SecKillConstant.CACHE_FOODS_COUNT + goodsId);
            if (stock > 0) {
                redisTemplate.opsForValue().increment(upActivityKey() + SecKillConstant.CACHE_FOODS_COUNT + goodsId);
                log.info("扣减库存成功，还剩:" + stock);
            }
            return "库存不足，该商品已抢购完！";
        } catch (Exception e) {

        } finally {
            lock.unlock();
        }
        return "fail";
    }

    /**
     * 获取活动
     *
     * @return
     */
    public ActivityBo upActivity() {

        return new ActivityBo("七夕活动", "SEVEN_ACTIVITY", new Date(), new Date());
    }

    /**
     * 活动公共key
     *
     * @return
     */
    public String upActivityKey() {
        return SecKillConstant.SEC_KILL + upActivity().getActivityKey() + ":";
    }
}

五、redis锁 单机版可用，分布式用Redisson

package com.yang.yimall.seckill.app.seckill.biz;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;

import java.util.Collections;
import java.util.UUID;
import java.util.concurrent.TimeUnit;

/**
 * redis 锁 集群有瑕疵 不能 续命
 */
@Service
public class RedisLock {

    @Autowired
    private RedisTemplate redisTemplate;

    private String lockName = "lockName";

    private ThreadLocal<String> threadLocal = new ThreadLocal<>();

    public void lock(String lockName) {
        if (tryLock(lockName)) {
            return;
        }
        lock(lockName);
    }

    public void lock() {
        if (tryLock(lockName)) {
            return;
        }
        lock();

    }

    /**
     * 添加key 并且设置过期时间 原子操作
     *
     * @param lockName
     * @return
     */
    public boolean tryLock(String lockName) {
        String uuid = UUID.randomUUID().toString();
        threadLocal.set(uuid);
        return redisTemplate.opsForValue().setIfAbsent(lockName, uuid, 30, TimeUnit.SECONDS);
    }

    /**
     * 如果查询有key，就删除， 原子操作
     */
    public void unlock() {
        String script = "if redis.call('get',KEYS[1]) == ARGV[1] then return redis.call('del',KEYS[1]) else return 0 end";
        redisTemplate.execute(new DefaultRedisScript<Long>(script, Long.class), Collections.singletonList(lockName), threadLocal.get());
    }

}

使用

 public String doKillUp() {
        String goodsId = "10054";
        redisLock.lock(goodsId);
        // 获取锁成功
        try {
            Long stock = redisTemplate.opsForValue().decrement(upActivityKey() + SecKillConstant.CACHE_FOODS_COUNT + goodsId);
            if (stock > 0) {
                redisTemplate.opsForValue().increment(upActivityKey() + SecKillConstant.CACHE_FOODS_COUNT + goodsId);
                log.info("扣减库存成功，还剩:" + stock);
            }
            return "库存不足，该商品已抢购完！";
        } catch (Exception e) {

        } finally {
            redisLock.unlock();
        }
        return "库存不足，该商品已抢购完！";
    }