<dependency>
  <groupId>org.redisson</groupId>
  <artifactId>redisson</artifactId>
  <version>3.17.3</version>
</dependency>

@Bean
    public Redisson redisson(){
        //redis为单机模式
        Config config = new Config();
        config.useSingleServer().setAddress("redis://localhost:6379").setPassword("123456");
        return (Redisson) Redisson.create(config);
    }

package com.fast.controller;

import org.redisson.Redisson;
import org.redisson.api.RLock;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

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

/**
 * @author hjw
 * @since 2022年06月23日 11:42:00
 */
@RestController
@RequestMapping("stock")
public class StockController {
    @Autowired
    private RedisTemplate redisTemplate;
    @Autowired
    private Redisson redisson;

    @GetMapping("init")
    public String init() {
        redisTemplate.opsForValue().set("stock", 100);

        return "库存新增成功";
    }

    @GetMapping("sale")
    public String saleGoods() {
        //这样写，单机部署不会有问题，多节点就会出问题，因为synchronized只能基于jvm做加锁，多个节点属于多个jvm了
        synchronized (this) {
            int stock = (int) redisTemplate.opsForValue().get("stock");
            if (stock > 0) {
                int i = stock - 1;
                redisTemplate.opsForValue().set("stock", i);
                System.out.println("库存剩余:" + i);
            } else {
                System.out.println("库存数量不足");
                return "库存数量不足";
            }
        }
        return "库存扣减成功";
    }

    @GetMapping("saleImprove")
    public String saleImprove() {
        //使用redisson实现分布式锁
        String lockKey = "product_001";
//        String clientId = UUID.randomUUID().toString();
        **RLock redissonLock = redisson.getLock(lockKey);**
        try {
            //使用redisTemplate还需要手写子线程每隔30s*1/3=10s，根据clientId给每个线程的lockKey进行续期，防止lockKey失效后，业务未执行完，结果下个线程进来了
//            Boolean result = redisTemplate.opsForValue().setIfAbsent(lockKey,clientId,30, TimeUnit.SECONDS);
//            if (!result){
//                return "error_code";
//            }
            **redissonLock.lock();**//相当于setIfAbsent(lockKey,clientId,30, TimeUnit.SECONDS);
            int stock = (int) redisTemplate.opsForValue().get("stock");
            if (stock > 0) {
                int i = stock - 1;
                redisTemplate.opsForValue().set("stock", i);
                System.out.println("库存剩余:" + i);
            } else {
                System.out.println("库存数量不足");
                return "库存数量不足";
            }
        }finally {
            **redissonLock.unlock();**
//            if (clientId.equals(redisTemplate.opsForValue().get(lockKey))){
//                redisTemplate.delete(lockKey);
//            }
        }
        return "库存扣减成功";
    }
}