Redis分佈式鎖、RedisTemplate、lettuce實現

 

springboot新版本使用lettuce取代了jedis連接redis,分佈式鎖實現代碼如下

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.connection.RedisStringCommands;
import org.springframework.data.redis.connection.ReturnType;
import org.springframework.data.redis.core.RedisCallback;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.types.Expiration;
import org.springframework.stereotype.Component;

import java.nio.charset.StandardCharsets;
import java.util.Objects;
import java.util.concurrent.TimeUnit;

/**
 * @author Vick C
 * @Description: 分佈式鎖工具類
 * @CreateDate: 2020/05/29
 */
@Component
@Slf4j
public class RedisLock {

    @Autowired
    private RedisTemplate<String, Object> redisTemplate;

    /**
     * 釋放鎖腳本，原子操作，lua腳本
     */
    private static final String UNLOCK_LUA;
    /**
     * 默認過期時間(30ms)
     */
    private static final long DEFAULT_EXPIRE = 30L;

    static {
        StringBuilder sb = new StringBuilder();
        sb.append("if redis.call(\"get\",KEYS[1]) == ARGV[1] ");
        sb.append("then ");
        sb.append("    return redis.call(\"del\",KEYS[1]) ");
        sb.append("else ");
        sb.append("    return 0 ");
        sb.append("end ");
        UNLOCK_LUA = sb.toString();
    }

    /**
     * 獲取分佈式鎖，原子操作
     * @param lockKey   鎖
     * @param lockValue 唯一ID, 可以使用UUID.randomUUID().toString();
     * @return 是否枷鎖成功
     */
    public boolean lock(String lockKey, String lockValue) {
        return this.lock(lockKey, lockValue, DEFAULT_EXPIRE, TimeUnit.MILLISECONDS);
    }

    /**
     * 獲取分佈式鎖，原子操作
     * @param lockKey   鎖
     * @param lockValue 唯一ID, 可以使用UUID.randomUUID().toString();
     * @param expire    過期時間
     * @param timeUnit  時間單位
     * @return 是否枷鎖成功
     */
    public boolean lock(String lockKey, String lockValue, long expire, TimeUnit timeUnit) {
        try {
            RedisCallback<Boolean> callback = (connection) -> connection.set(lockKey.getBytes(StandardCharsets.UTF_8),
                    lockKey.getBytes(StandardCharsets.UTF_8), Expiration.seconds(timeUnit.toSeconds(expire)),
                    RedisStringCommands.SetOption.SET_IF_ABSENT);
            return redisTemplate.execute(callback);
        } catch (Exception e) {
            log.error("redis lock error ,lock key: {}, value : {}, error info : {}", lockKey, lockValue, e);
        }
        return false;
    }

    /**
     * 釋放鎖
     * @param lockKey   鎖
     * @param lockValue 唯一ID
     * @return 執行結果
     */
    public boolean unlock(String lockKey, String lockValue) {
        RedisCallback<Boolean> callback = (connection) -> connection.eval(UNLOCK_LUA.getBytes(), ReturnType.BOOLEAN, 1, lockKey.getBytes(StandardCharsets.UTF_8), lockValue.getBytes(StandardCharsets.UTF_8));
        return redisTemplate.execute(callback);
    }

    /**
     * 獲取Redis鎖的value值
     * @param lockKey 鎖
     */
    public String get(String lockKey) {
        try {
            RedisCallback<String> callback = (connection) -> new String(Objects.requireNonNull(connection.get(lockKey.getBytes())), StandardCharsets.UTF_8);
            return redisTemplate.execute(callback);
        } catch (Exception e) {
            log.error("get redis value occurred an exception,the key is {}, error is {}", lockKey, e);
        }
        return null;
    }

}