1.引入依赖

<!--导入Lombok依赖-->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
</dependency>
<!--Spring Data Redis 的启动器 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson</artifactId>
    <version>3.7.5</version>
</dependency>

2.配置 application.properties

# Redis服务器地址
spring.redis.host=xxxxx
# Redis服务器连接密码（默认为空）
spring.redis.password=11111
# Redis服务器连接端口
spring.redis.port=6379

3.Redisson的配置类（初始化配置）

import org.redisson.Redisson;
import org.redisson.api.RedissonClient;
import org.redisson.config.Config;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
 
import java.io.IOException;
 
@Configuration
public class RedissonConfig {
 
    @Value("${spring.redis.host}")
    private String host;
 
    @Value("${spring.redis.port}")
    private String port;
 
    //@Value("${spring.redis.password}")
    //private String password;
 
    /**
     * RedissonClient,单机模式
     * @return
     * @throws IOException
     */
    @Bean(destroyMethod = "shutdown")
    public RedissonClient redisson() throws IOException {
        Config config = new Config();
        //config.useSingleServer().setAddress("redis://" + host + ":" + port).setPassword(password);
        config.useSingleServer().setAddress("redis://" + host + ":" + port);
        return Redisson.create(config);
    }
}

4.实现业务

import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.stereotype.Service;
 
import javax.annotation.Resource;
import java.util.concurrent.TimeUnit;
 
@Slf4j
@Service
public class SkillService {
    @Resource
    RedissonClient redissonClient;
 
    private final static String LOCK_KEY = "RESOURCE_KEY";
    int n = 500;
 
    public void seckill() {
        //定义锁
        RLock lock = redissonClient.getLock(LOCK_KEY);
        //lock.lock();
        try {
            //尝试加锁,最大等待时间300毫秒，上锁30毫秒自动解锁
            if (lock.tryLock(300, 30, TimeUnit.MILLISECONDS)) {
                log.info("线程:" + Thread.currentThread().getName() + "获得了锁");
                log.info("剩余数量:{}", --n);
            }
        } catch (Exception e) {
            log.error("程序执行异常:{}", e);
        } finally {
            log.info("线程:" + Thread.currentThread().getName() + "准备释放锁");
            //释放锁
            lock.unlock();
        }
    }
}

5.测试

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
 
@RestController
public class SkillServiceTest {
 
    @Autowired
    SkillService service;
 
    @RequestMapping("/testSkillService")
    public void TestSkillService(){
        for (int i = 10; i < 60; i++) { //开50个线程
            SkillThread skillThread = new SkillThread(service, "skillThread->" + i);
            skillThread.start();
        }
    }
}
 
class SkillThread extends Thread {
 
    private SkillService skillService;
 
    public SkillThread(SkillService skillService, String skillThreadName) {
        super(skillThreadName);
        this.skillService = skillService;
    }
 
    @Override
    public void run() {
        skillService.seckill();
    }
}

1.解析getLock
初始化RedissonLock对象 ，并且根据入参名字相当于创建了一个全局的key的锁

2.lock.lock()
找到实现方法核心

然后找到重新方法，核心下图

重点在下图，主要实现，然后执行里面的lua脚本语言，返回 数据，就算就算加上锁了（广播0表示资源可用）
这里用的数据结构是hash，hash的结构是： key 字段1 值1 字段2 值2 。。。
用在锁这个场景下，key就表示锁的名称，也可以理解为临界资源，字段就表示当前获得锁的线程
所有竞争这把锁的线程都要判断在这个key下有没有自己线程的字段，如果没有则不能获得锁，如果有，则相当于重入，字段值加1（次数）

1. （正常情况下可以获取到锁）
private Long tryAcquire(long leaseTime, TimeUnit unit, long threadId) {
    return get(tryAcquireAsync(leaseTime, unit, threadId));
}


2.
private <T> RFuture<Long> tryAcquireAsync(long leaseTime, TimeUnit unit, long threadId) {
    if (leaseTime != -1) {
        return tryLockInnerAsync(leaseTime, unit, threadId, RedisCommands.EVAL_LONG);
    }
    RFuture<Long> ttlRemainingFuture = tryLockInnerAsync(commandExecutor.getConnectionManager().getCfg().getLockWatchdogTimeout(), TimeUnit.MILLISECONDS, threadId, RedisCommands.EVAL_LONG);
    ttlRemainingFuture.onComplete((ttlRemaining, e) -> {
        if (e != null) {
            return;
        }

        // lock acquired
        if (ttlRemaining == null) {
            scheduleExpirationRenewal(threadId);
        }
    });
    return ttlRemainingFuture;
}


3.执行脚本语言（核心参数为  getName()  getLockName(threadId)线程id）
<T> RFuture<T> tryLockInnerAsync(long leaseTime, TimeUnit unit, long threadId, RedisStrictCommand<T> command) {
    internalLockLeaseTime = unit.toMillis(leaseTime);
    return commandExecutor.evalWriteAsync(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.<Object>singletonList(getName()), internalLockLeaseTime, getLockName(threadId));
}

解析锁：lock.unlock();
找到实现方法，unlockAsync())
然后找里面的核心方法，主要是执行lua脚本