redis实现分布式锁

redis的分布式锁核心在 setnx 方法，成功返回1，失败返回0

案例：搭建springboot集成redis实现分布式锁，100个线程同时生产订单号场景

思路：

1，获取锁，成功执行第2步，失败就等待获取锁成功

2，执行业务

3，释放锁

        
         
            org.springframework.boot
            spring-boot-starter-web
            2.6.2
        

        
        
            org.springframework.boot
            spring-boot-starter-data-redis
            2.6.3
        

package com.hyw.util;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;
import java.time.Duration;
import java.util.concurrent.TimeUnit;

@Component
public class RedisUtil {

    
    @Autowired
    private StringRedisTemplate redis;

    public void setStr(String key, String value){
        setStr(key, value, null);
    }

    
    public void setStr(String key, String value, Long timeOut){
        redis.opsForValue().set(key, value);
        if(timeOut != null)
            redis.expire(key, timeOut, TimeUnit.SECONDS);
    }

    
    public Integer setnx(String key, String value, Long timeOut){
        boolean flag = redis.opsForValue().setIfAbsent(key,value, timeOut, TimeUnit.SECONDS);

        return flag?1:0;
    }

    public Integer setnx(String key, String value){
        return setnx(key, value, null);
    }

    
    public void del(String key){
        redis.delete(key);
    }

    public String getStr(String key){
        return redis.opsForValue().get(key);
    }
}

package com.hyw.lock;

import com.hyw.contans.OrderContans;
import com.hyw.util.RedisUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.UUID;

@Component
public class RedisLock {
    @Autowired
    private RedisUtil redisUtil;

    public String getLock(String lockKey, int notLockTime){

        //计算尝试获取锁超时时间
        Long endTime = System.currentTimeMillis() + notLockTime;

        //超时就退出循环
        while (System.currentTimeMillis() < endTime){
            String lockValue = UUID.randomUUID().toString();
            if(redisUtil.setnx(lockKey, lockValue, notLockTime*1l/1000) == OrderContans.lockSuccess){
                System.out.println(Thread.currentThread().getName() +"获取锁成功！");
                return lockValue;
            }
            try {
                Thread.sleep(10);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        return null;
    }

    
    public void unlock(String lockKey, String lockValue){
        //判断lockValue 是否抢到锁的用户，是就删除，避免把别人的锁给删了
        if(lockValue.equals(redisUtil.getStr(lockKey))){
            redisUtil.del(lockKey);
            System.out.println(Thread.currentThread().getName() +"释放锁成功！");
        }
    }

}

package com.hyw.contans;

public class OrderContans {
    
    public static int lockSuccess = 1;

    
    public static final String LOCK_KEY = "order_lock";


    
    public static int notLockTime = 10000;
}

package com.hyw.service;

import com.hyw.contans.OrderContans;
import com.hyw.lock.RedisLock;
import com.hyw.util.OrderUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;

@Component
public class OrderService {

    @Autowired
    private RedisLock redisLock;

    public void getOrderNum(){
        //1.获取锁
        String lockValue = redisLock.getLock(OrderContans.LOCK_KEY, OrderContans.notLockTime);

        if(StringUtils.isEmpty(lockValue)){
            System.out.println("获取锁失败！");
            return;
        }
        System.out.println("获取订单号成功..."+ OrderUtil.getOrderNumber());


        //3.释放锁
        redisLock.unlock(OrderContans.LOCK_KEY, lockValue);
        System.out.println();
    }

}

package com.hyw.controller;

import com.hyw.service.OrderService;
import com.hyw.util.RedisUtil;

@RestController
public class OrderController {

    @Autowired
    private RedisUtil redisUtil;
    @Autowired
    private OrderService orderService;
 
    
    @RequestMapping("/getOrderNum")
    public String getOrderNum(){
        for (int i = 0; i < 100; i++) {
            new Thread(new Runnable() {
                public void run() {
                    orderService.getOrderNum();
                }
            }).start();
        }

        return "success";
    }
}

package com.hyw;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.text.SimpleDateFormat;
import java.util.Date;

@SpringBootApplication
public class ApplicationMain {
    public static void main(String[] args) {
        SpringApplication.run(ApplicationMain.class, args);
    }
}

运行结果：

http://localhost:8888/getOrderNum