关于redis锁的详解

引用    https://www.jb51.net/article/251428.htm

 Lock lock = new ReentrantLock();
    @Autowired
    StringRedisTemplate redisTemplate;
    public static final String g01="good:01";
    public static final String REDIS_LOCK="good_lock";
    @ApiOperation("获取测试数据")
    @GetResource(name = "获取测试数据", path = "/getTestInfo", requiredPermission = false,requiredLogin = false)
    public ResponseData getTestInfo(@RequestParam ("num") int num){
        String value = UUID.randomUUID().toString().replace("-", "");
        UUID.randomUUID().toString().replace("-","");
        try {
            Boolean flag = redisTemplate.opsForValue().setIfAbsent(REDIS_LOCK, value,10, TimeUnit.SECONDS);
            if (!flag) return ResponseData.error("抢锁失败");
            log.info("抢锁成功");
            String result = redisTemplate.opsForValue().get(g01);
            int total = result==null ? 0:Integer.parseInt(result);
            if (total>0){
                total--;
                redisTemplate.opsForValue().set(g01,String.valueOf(total));
                return ResponseData.success(total);
            }
            return ResponseData.error("没有库存");
        }catch (Exception e){
            return ResponseData.error("报错");
        }finally {
//            redisTemplate.delete(REDIS_LOCK);
//            if (redisTemplate.opsForValue().get(REDIS_LOCK).equals(value)){
//                redisTemplate.delete(REDIS_LOCK);
//            }
            Jedis jedis = null;
            try {
                jedis = new Jedis("119.45.11.7", 6379);
                jedis.auth("LIKZ10101006");
                String script = "if redis.call('get',KEYS[1]) == ARGV[1] " +
                        "then " +
                        "return redis.call('del',KEYS[1]) " +
                        "else " +
                        "   return 0 " +
                        "end";
                Object eval = jedis.eval(script, Collections.singletonList(REDIS_LOCK),
                        Collections.singletonList(value));
                if("1".equals(eval.toString())){
                    log.info("-----del redis lock ok....");
                }else {
                    log.info("-----del redis lock error....");
                }
            }catch (Exception e){

            }finally {
                if (null!=jedis){
                    jedis.close();
                }
            }
        }

    }

正常加锁

 String value = UUID.randomUUID().toString().replace("-","");
        try{
            // 为key加一个过期时间
            Boolean flag = template.opsForValue().setIfAbsent(REDIS_LOCK, value,10L,TimeUnit.SECONDS);
 
            // 加锁失败
            if(!flag){
                return "抢锁失败！";
            }
            System.out.println( value+ " 抢锁成功");

 谁加了锁，谁才能删锁

finally {
            // 谁加的锁，谁才能删除！！！！
            if(template.opsForValue().get(REDIS_LOCK).equals(value)){
                template.delete(REDIS_LOCK);
            }
        }

使用lua脚本，保证原子性

finally {
            // 谁加的锁，谁才能删除，使用Lua脚本，进行锁的删除
 
            Jedis jedis = null;
            try{
                jedis = RedisUtils.getJedis();
 
                String script = "if redis.call('get',KEYS[1]) == ARGV[1] " +
                        "then " +
                        "return redis.call('del',KEYS[1]) " +
                        "else " +
                        "   return 0 " +
                        "end";
 
                Object eval = jedis.eval(script, Collections.singletonList(REDIS_LOCK), Collections.singletonList(value));
                if("1".equals(eval.toString())){
                    System.out.println("-----del redis lock ok....");
                }else{
                    System.out.println("-----del redis lock error ....");
                }
            }catch (Exception e){
 
            }finally {
                if(null != jedis){
                    jedis.close();
                }
            }
        }

目前存在锁，并属于当前线程

finally {
            if(lock.isLocked() && lock.isHeldByCurrentThread()){
                lock.unlock();
            }
        }