关于redis在项目中常见应用

关于redis在项目中常见应用采用自写接口

接口CacheService ，写方法对应每个功能；
实现类 RedisCacheServiceImpl，重写方法，写每个功能具体实现逻辑；
注入对应StringRedisTemplate；

@Autowired
private StringRedisTemplate template;

1、根据key获取String类型的value

String codeValue = cacheService.getValue(codeKey);

@Override
public String getValue(String key) {
    ValueOperations<String, String> ops = template.opsForValue();
     return ops.get(key);
 } 

2、向redis中存string类型的值

cacheService.setKey ( Key, value , expireSeconds , TimeUnit.SECONDS);

@Override
public void setKey(String key, String value) {
    ValueOperations<String, String> ops = template.opsForValue();
    ops.set(key,value);
}

存值设置值失效时间：

@Override
public void setKey(String key, String value, long timeOut, TimeUnit unit) {
    ValueOperations<String, String> ops = template.opsForValue();
    ops.set(key,value,timeOut,unit);
}

3、setnx锁

如果key不存在设置value值，返回true，存在返回false；

并发锁、原子操作、幂等性

// 设置redis锁
String key = "worship_packet_open_lock:" + phone + "_" + id;
if (!cacheService.setnx(key, userId.toString())) {
    throw new BusinessException(ErrorStatus.ILLEGAL_ARGUMENT, "正在拆红包，请勿重复点击");
}

@Override
public boolean setnx(String key, String value) {
    Boolean aBoolean = template.opsForValue().setIfAbsent(key, value);
    if (aBoolean) {
        template.opsForValue().set(key,value,60,TimeUnit.SECONDS);
    }
    return aBoolean;
}

4、根据key删除redis值

cacheService.delKey ( key )；

@Override
public void delKey(String key) {
    if (hasKey(key)) {
        template.delete(key);
    }
}

5、自增键

Long count = cacheService.getRedisSequence();

@Autowired
private RedisAtomicLong redisAtomicLong ;

@Override
public long getRedisSequence(){

    long sequence = 00001L;

    try {
        if(redisAtomicLong.get() == 00001){
            redisAtomicLong.getAndSet(00001L);
        }
        sequence = redisAtomicLong.incrementAndGet();
    }catch(Exception e){
        log.error("Failed to get sequence;自增失败" ,e);
    }

    return sequence ;
}

6、键每次新增次数

Long count = cacheService.boundValueOps(key + phone, 1);

@Override
public Long boundValueOps(String key, Integer num) {
    return template.boundValueOps(key).increment(num);
}

7、设置过期时间

cacheService.expire(key , 1L , TimeUnit.HOURS );

//指定缓存失效时间
@Override
public boolean expire(String key, long time, TimeUnit unit) {
    try {
        if (time > 0) {
            template.expire(key, time, unit);
        }
        return true;
    } catch (Exception e) {
        log.error(e.getMessage(),e);
        return false;
    }
}

8、判断key是否存在

Boolean exist = cacheService.hasKey(key);

@Override
public Boolean hasKey(String key) {
    return template.hasKey(key);
}

9、根据key计算redis中list长度

Long size = cacheService.maxlistsize(limitSendRedisKey);

@Override
public Long maxlistsize(String key) {
    ListOperations<String, String> opsForList = template.opsForList();
    return  opsForList.size(key);
}

10、list类型添加元素两种方式

LPush方法添加元素（从头部加入元素，先进后出、栈）

cacheService.leftPush(limitSendRedisKey, String.valueOf(redisTimeValue));

@Override
public Long leftPush(String key, String value) {
    ListOperations<String, String> opsForList = template.opsForList();
    return opsForList.leftPush(key,value);
}

list类型rPush方法添加元素（从尾部加入元素，先进先出、队列）

opsForList.rightPush(key,value);

11、删除list集合元素
lPop：从list的头部删除元素

//rPop：从list的尾部删除元素，并返回删除元素

cacheService.rightPop(limitSendRedisKey)

@Override
public String rightPop(String pop) {
    ListOperations<String, String> opsForList = template.opsForList();
    return  opsForList.rightPop(pop);
}

12、获取key当前剩余过期时间

long expire = cacheService.getExpire(countKey, timeUnit);

@Override
public long getExpire(String key, TimeUnit unit) {
    return template.getExpire(key, unit);
}

13、通过key获取原子数据

int optValueAtomic = cacheService.getOptValueAtomic(key);

@Override
public int getOptValueAtomic(String key) {
    int count = 0;
    if(Boolean.TRUE.equals(template.hasKey(key))){
        count = Integer.valueOf(getValue(key));
    }
    return count;
}

14、对数据进行加减原子性操作

*@param key   redis key
* @param isAdd  是否是新增
* @param changeValue  需要更该的参数（加几减几）

cacheService.optAtomic(key , true , count );

@Override
public int optAtomic(String key, boolean isAdd, Integer changeValue) {
   //通过key获取原子数据
    int optValueAtomic = getOptValueAtomic(key);
    RedisAtomicInteger counter;
    if(!isAdd && optValueAtomic < changeValue){
        throw  new BusinessException(ErrorStatus.ILLEGAL_DATA,"库存已不足");
    }
    if(Boolean.TRUE.equals(template.hasKey(key))){
        return isAdd ? Integer.valueOf(template.opsForValue().increment(key, changeValue).toString()) :Integer.valueOf(template.opsForValue().increment(key, -changeValue).toString());
    }else{
        counter =  new RedisAtomicInteger(key, Objects.requireNonNull(template.getConnectionFactory()),optValueAtomic);
        return isAdd ? counter.addAndGet(changeValue) : counter.addAndGet(-changeValue);
    }
}