java如何使用redis加锁-编程学习网

java使用redis加锁

1.编写LockUtil工具类

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.connection.RedisStringCommands.SetOption;
import org.springframework.data.redis.core.RedisCallback;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.types.Expiration;
import org.springframework.stereotype.Service;
 

@Service
public class LockUtil {
 
    @Autowired
    private RedisTemplate redisTemplate;
 
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
 
    
    public boolean lock(String lockKey, int lockSeconds) {
        return (Boolean) redisTemplate.execute((RedisCallback) connection -> {
            byte[] key = lockKey.getBytes();
            Boolean set = connection.set(key, key, Expiration.seconds(lockSeconds), SetOption.SET_IF_ABSENT);
            if (set == null) {
                return false;
            }
            return set;
        });
    }
 
    public boolean isLock(String lockKey) {
        return stringRedisTemplate.opsForValue().get(lockKey)!=null;
    }
 
 
    public boolean clearLock(String lockKey){
       return redisTemplate.delete(lockKey);
    }
}

2.使用锁

public abstract class AbstractTask {
 
    @Autowired
    private LockUtil lockUtil;
 
    
    protected abstract String getLockKey();
 
    protected boolean lock() {
        return lockUtil.lock(getLockKey(), 120);
    }
 
    protected boolean lockManual() {
        return lockUtil.lock(getLockKey(), 299);
    }
 
    protected boolean clearLock() {
        return lockUtil.clearLock(getLockKey());
    }
}

@Component
@Slf4j
@RefreshScope
public class FileCapacityCountTask extends AbstractTask{
    @Autowired
    private FileCapacityCountService fileCapacityCountService;
   
 
    @Scheduled(cron = "${batch.verification.schedule.capacity}")
    public void task(){
        if (!lock()) {
            log.info("本实例无需执行定时任务");
            return;
        }
        fileCapacityCountService.fileCapacityCountTask();
    }
 
    @Override
    protected String getLockKey() {
        String today = DateUtil.formatDate(new Date());
        return FileCapacityCountTask.class.getSimpleName() + CommonConstant.APPLICATION_NAME + today;
    }
}

redis锁用法java代码

由于redis是串行的，所以可以用redis实现锁机制。

下方是java代码：

@Component
@Slf4j
public class RedisSingleLock {
    private final StringRedisTemplate redis;

    public SimpleDistributedLock(StringRedisTemplate redis) {
        this.redis = redis;
    }

    //这个方法，可以传入key加锁；多线程调用时，只有1个能获取锁成功，其它线程则会进入循环，不停尝试获取锁
    public void lock(String key) {
        do {
            Boolean lockSuccess = redis.opsForValue().setIfAbsent(key, "1", 1, TimeUnit.DAYS);
            if (lockSuccess == null) {
                throw new IllegalStateException();
            }
            if (!lockSuccess) {
                try {
                    TimeUnit.MILLISECONDS.sleep(100);
                } catch (InterruptedException e) {
                    log.error(e.getMessage(), e);
                }
            } else {
                break;
            }
        } while (true);
    }

    //这个方法，传入key释放锁，当持有锁的线程执行业务代码完毕后调用，释放这个锁；上方某一个在lock方法中循环尝试获得锁的线程可以获得锁，另外的线程则继续循环等待
    public void releaseLock(String key) {
        redis.delete(key);
    }
	
	//这个方法只尝试获取一次锁，返回获取结果
    public boolean tryLock(String key) {
        Boolean lockSuccess = redis.opsForValue().setIfAbsent(key, "1", 1, TimeUnit.DAYS);
        if (lockSuccess == null) {
            throw new IllegalStateException();
        }

        return lockSuccess;
    }
}