1.RedisTempla使用Scan
@Component
public class ScanDemo {
@Autowired
private StringRedisTemplate redisTemplate;
public void test() {
for (int i = 0; i < 100; i++) {
redisTemplate.opsForValue().set("b" + i, "1");
}
ScanOptions scanOptions = ScanOptions.scanOptions().match("b*").count(2).build();
Cursor<String> cursor = redisTemplate.scan(scanOptions);
while (cursor.hasNext()){
System.out.println(cursor.next());
}
cursor.close();
}
}
Java
2.lua脚本操作Redis
一次扣减一个商品库存
@Component
public class LuaDemo {
@Autowired
private StringRedisTemplate redisTemplate;
public void test() {
List<String> keys = new ArrayList<>();
keys.add("yanjie007");
String lua = "return redis.call('set',KEYS[1],ARGV[1])";
RedisScript<String> redisScript= RedisScript.of(lua,String.class);
String shuai = stringRedisTemplate.execute(redisScript, keys, "今天真帅");
System.out.println(shuai);
}
}
//扣减库存 @Test
void test2() throws IOException {
valueOperations.set(key,15L);
StringBuilder sb = new StringBuilder();
sb.append(" local key = KEYS[1] ");
sb.append(" local qty = ARGV[1] ");
sb.append(" local redis_qty = redis.call('get',key) ");
sb.append(" if tonumber(redis_qty) >= tonumber(qty) then ");
sb.append(" redis.call('decrby',key,qty) ");
sb.append(" return -1 ");
sb.append(" else ");
sb.append(" return tonumber(redis_qty) "); // 0, 1,2,3 ....
sb.append(" end ");
sb.append(" ");
RedisScript<Long> script = RedisScript.of(sb.toString(),Long.class);
ExecutorService executorService = Executors.newCachedThreadPool();
for (int i = 1; i <= 10; i++) {
int finalI = i;
executorService.execute(()->{
int needQty = RandomUtil.randomInt(1, 5);
Long qty = stringRedisTemplate.execute(script, CollUtil.newArrayList(key), needQty+"");
if(qty.intValue() == -1 ){
System.out.println("线程"+ finalI +"扣减成功,需求量是："+needQty);
} else {
System.out.println("线程"+ finalI +"扣减失败,当前库存变量是："+qty);
}
});
}
System.in.read();
}
Java
一次扣减多个商品的库存
void test4() {
StringBuilder sb = new StringBuilder();
sb.append(" local table = {} "); // 你要扣减的key ：product.1
sb.append(" local values = redis.call('mget', unpack(KEYS) )"); // [product.1,product.2] => product.1 product.2
sb.append(" for i = 1, #KEYS do ");
sb.append(" if tonumber(ARGV[i]) > tonumber(values[i]) then ");
sb.append(" table[#table + 1] = KEYS[i] .. '=' .. values[i] "); // product.1=23
sb.append(" end ");
sb.append(" end ");
sb.append(" if #table > 0 then ");
sb.append(" return table ");
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 {} ");
RedisScript<List> luaScript = RedisScript.of(sb.toString(), List.class);
List<StockProduct> stockProducts = new ArrayList<>();
stockProducts.add(new StockProduct(5,1));
stockProducts.add(new StockProduct(4,2));
List<String> keys = stockProducts.stream().map(it -> "product." + it.getId()).collect(Collectors.toList());
Object[] qtys = stockProducts.stream().map(it -> it.getQty() + "").toArray();
List<String> list = stringRedisTemplate.execute(luaScript,
keys,
qtys);
if(list.isEmpty()){
System.out.println("库存冻结成功");
} else {
for (String key_qty : list) {
String[] split = key_qty.split("=");
System.out.println(split[0] + "库存不足，剩余库存量：" + split[1]);
}
}
ThreadUtil.safeSleep(3000);
}
Java
3.模拟多线程并发使用Decrby
@Component
public class DecrByDemo {
@Resource(name = "redisTemplate")
private ValueOperations<String, Integer> valueOperations;
private static final String key = "product.01";
public void test() throws InterruptedException {
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()));
}
});
}
Thread.sleep(10*1000);
}
public void test2() throws InterruptedException {
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()));
}
});
}
Thread.sleep(10*1000);
}
}
Java
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;
private static final String key = "product.1";
public void test() throws InterruptedException {
//出入库场景 商品1
ExecutorService executorService = Executors.newCachedThreadPool();
for(int i =1; i<6;i++){
executorService.execute(()->{
// 获取分布式锁
while (true){
Boolean b = valueOperations.setIfAbsent("product.1", "IO202303170929,"+ 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("product.1");
break;
} else {
System.out.println(Thread.currentThread().getName() + " 获取锁失败" );
ThreadUtil.safeSleep(2000);
}
}
});
}
System.in.read();
}
}
Java
5.BitMap模拟在线统计
@Component
public class BitMapDemo {
@Resource(name = "redisTemplate")
private ValueOperations valueOperations;
@Autowired
private 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 = "20200601#20200602#20200603";
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);
}
}
Java