1.使用Scan
2.lua脚本操作Redis
一次扣减一个商品库存
一次扣减多个商品的库存
@Testvoid test100() {String key = "product.1";stringRedisTemplate.opsForValue().set("product.1","10");stringRedisTemplate.opsForValue().set("product.2","20");stringRedisTemplate.opsForValue().set("product.3","30");}@Test //模拟下单扣多个商品库存void test3() {ArrayList<FreezeProduct> freezeProducts = CollUtil.newArrayList(new FreezeProduct().setProductId(1).setQty(5),new FreezeProduct().setProductId(2).setQty(5),new FreezeProduct().setProductId(3).setQty(5));StringBuilder sb = new StringBuilder();// 1. 我要知道需求量是多少 ，还要知道是哪个keysb.append(" local myTable = {} ");// 2. 我要判断目前的库存量是否满足需求量sb.append(" local redisQtys = redis.call('mget',unpack(KEYS)) ");sb.append(" for i = 1, #KEYS do ");sb.append(" if tonumber(ARGV[i]) > tonumber(redisQtys[i]) then ");sb.append(" myTable[#myTable + 1] = KEYS[i] .. '=' .. redisQtys[i] ");sb.append(" end ");sb.append(" end ");// 3. myTable 有元素 return ，没有元素 就扣sb.append(" if #myTable > 0 then ");sb.append(" return myTable ");sb.append(" end ");sb.append(" for i = 1 , #KEYS do");sb.append(" redis.call('decrby',KEYS[i],ARGV[i]) ");sb.append(" end ");sb.append(" return {} ");// 返回 ： 如果不足 集合 ，如果 满足：空集合RedisScript<List> script = RedisScript.of(sb.toString(),List.class);List<String> keys = freezeProducts.stream().map(it -> "product." + it.getProductId()).collect(Collectors.toList());Object[] qtys = freezeProducts.stream().map(it -> it.getQty() + "").toArray();List list = stringRedisTemplate.execute(script, keys,qtys);if(list.isEmpty()){System.out.println(StrUtil.format("下单成功"));} else {System.out.println(StrUtil.format("下单失败，{}",list));}}
3.模拟多线程并发使用Decrby
public class DecrByDemo {@Resource(name = "redisTemplate")private ValueOperations<String, Integer> valueOperations;private static final String key = "product.01";public void test() {valueOperations.set(key, 5);ExecutorService executorService = Executors.newCachedThreadPool();for (int i = 0; i < 10; i++) {executorService.execute(() -> {Integer value = valueOperations.get(key);if (value >= 1) {valueOperations.set(key, value - 1);System.out.println(StrUtil.format("线程{} -> 扣减成功", Thread.currentThread().getName()));} else {System.out.println(StrUtil.format("线程{} -> 扣减失败", Thread.currentThread().getName()));}});}System.in.read();}public void test2() {valueOperations.set(key, 5);ExecutorService executorService = Executors.newCachedThreadPool();for (int i = 0; i < 10; i++) {executorService.execute(() -> {Long value = valueOperations.decrement(key);if (value >= 0) {System.out.println(StrUtil.format("线程{} -> 扣减成功,剩余库存{}", Thread.currentThread().getName(),value));} else {System.out.println(StrUtil.format("线程{} -> 扣减失败", Thread.currentThread().getName()));}});}System.in.read();}
}
4.模拟多线程并发获取分布式锁SetNX
@Component
public class SetNxDemo {@Resource(name = "redisTemplate")private ValueOperations<String, String> valueOperations;public void test() throws InterruptedException {//出入库场景 ExecutorService executorService = Executors.newCachedThreadPool();for(int i =1; i<6;i++){executorService.execute(()->{while (true){// 获取分布式锁Boolean b = valueOperations.setIfAbsent("wms.io.locker", DateUtil.now());if(b){System.out.println(Thread.currentThread().getName() + " 获取到了分布式锁" );ThreadUtil.safeSleep(5000); //模拟业务操作stringRedisTemplate.delete("wms.io.locker");break;} else {System.out.println(Thread.currentThread().getName() + " 获取锁失败,睡眠2s" );ThreadUtil.safeSleep(2000);}}});}System.in.read();}}
5.BitMap
签到
@Component
public class BitMapDemo {@Autowiredprivate StringRedisTemplate stringRedisTemplate;private final String key ="sign.2024.zhouxingxing";public void test(){//设置签到stringRedisTemplate.opsForValue().setBit(key,2,true);stringRedisTemplate.opsForValue().setBit(key,85,true);//获取周星星同学的签到天数RedisCallback<Long> callback = connection -> { return connection.bitCount(key.getBytes(),0,365);};Long count = stringRedisTemplate.execute(callback);//打印周星星2024年签到天数System.out.println("周星星2024年一共签到天数："+count);}
}
模拟在线统计
@Component
public class BitMapDemo {@Resource(name = "redisTemplate")private ValueOperations valueOperations;@Autowiredprivate StringRedisTemplate redisTemplate;private static final int user01 = 1;private static final int user02 = 2;private static final int user03 = 3;private static String key20220601 = "20200601";private static String key20220602 = "20200602";private static String key20220603 = "20200603";private static String saveKey = "q1";public void test() {valueOperations.setBit(key20220601, user01, true);valueOperations.setBit(key20220601, user02, true);valueOperations.setBit(key20220602, user02, true);valueOperations.setBit(key20220603, user01, true);valueOperations.setBit(key20220603, user03, true);//1. 一直在线人数统计//2. 时间段活跃用户RedisCallback<Long> callback = connection -> {return connection.bitOp(RedisStringCommands.BitOperation.AND, saveKey.getBytes(),key20220601.getBytes(), key20220602.getBytes(), key20220603.getBytes());};Long value = redisTemplate.execute(callback);RedisCallback<Long> callback2 = connection -> {return connection.bitCount(saveKey.getBytes());};Long value2 = redisTemplate.execute(callback2);System.out.println(value2);}}
； 背后的奥秘)
