在高并发的情况下，比如秒杀，很多用户访问网页，评论网页，我们要记录商品数，浏览量，评论数，如果每一次请求后都去数据库中update字段，服务器很容易卡死。因为在更新数据库的时候，对该字段的行是上锁的。解决的办法是将数组存到某一个地方，每次收到请求后服务器先记录，每隔一段时间写回数据库中，这样用户看到的是一秒前的访问量，过了一秒，访问量蹭的上去了，对于用户来说一秒反应是没什么感觉的，对于服务器能防止卡死。可以将值存到Redis中。
Redis可以设置有效期，在登陆的时候可以用到，把用户登陆服务器下发的token存到Redis中，设置过期时间，时间到自动删除了。比存在数据库中判断expired_time更方便。
public class JedisAdapter implements InitializingBean {
private static final Logger logger = LoggerFactory.getLogger(JedisAdapter.class);
private Jedis jedis = null;
private JedisPool pool = null;
public static void print(int index, Object obj) {
System.out.println(String.format("%d,%s", index, obj.toString()));
}
public static void main(String[] args) {
Jedis jedis = new Jedis();
print(3, jedis.keys("*"));
jedis.flushAll();
// get,set
jedis.set("hello", "world");
print(1, jedis.get("hello"));
jedis.rename("hello", "newhello");
print(1, jedis.get("newhello"));
jedis.setex("hello2", 15, "world"); //有过期时间
try {
Thread.sleep(20000);
} catch (InterruptedException e) {
e.printStackTrace();
}
// 数值操作
jedis.set("pv", "100");
jedis.incr("pv");
jedis.decrBy("pv", 5);
print(2, jedis.get("pv"));
print(3, jedis.keys("*"));
// 列表操作, 最近来访, 粉丝列表，消息队列
String listName = "list";
jedis.del(listName);
for (int i = 0; i < 10; ++i) {
jedis.lpush(listName, "a" + String.valueOf(i)); //从左推进去
}
print(4, jedis.lrange(listName, 0, 12)); // 最近来访10个id
print(5, jedis.llen(listName));
print(6, jedis.lpop(listName));
print(7, jedis.llen(listName));
print(8, jedis.lrange(listName, 2, 6)); // 最近来访10个id
print(9, jedis.lindex(listName, 3));
print(10, jedis.linsert(listName, BinaryClient.LIST_POSITION.AFTER, "a4", "xx"));
print(10, jedis.linsert(listName, BinaryClient.LIST_POSITION.BEFORE, "a4", "bb"));
print(11, jedis.lrange(listName, 0, 12));
// hash, 可变字段
String userKey = "userxx";
jedis.hset(userKey, "name", "jim");
jedis.hset(userKey, "age", "12");
jedis.hset(userKey, "phone", "18666666666");
print(12, jedis.hget(userKey, "name"));
print(13, jedis.hgetAll(userKey));
jedis.hdel(userKey, "phone");
print(14, jedis.hgetAll(userKey));
print(15, jedis.hexists(userKey, "email"));
print(16, jedis.hexists(userKey, "age"));
print(17, jedis.hkeys(userKey));
print(18, jedis.hvals(userKey));
jedis.hsetnx(userKey, "school", "zju"); //hset if not exist
jedis.hsetnx(userKey, "name", "yxy");
print(19, jedis.hgetAll(userKey));
// 集合，点赞用户群, 共同好友
String likeKey1 = "newsLike1";
String likeKey2 = "newsLike2";
for (int i = 0; i < 10; ++i) {
jedis.sadd(likeKey1, String.valueOf(i));
jedis.sadd(likeKey2, String.valueOf(i * 2));
}
print(20, jedis.smembers(likeKey1));
print(21, jedis.smembers(likeKey2));
print(22, jedis.sunion(likeKey1, likeKey2)); //求并 可以用来求共同好友，共同规范
print(23, jedis.sdiff(likeKey1, likeKey2));//求互异
print(24, jedis.sinter(likeKey1, likeKey2)); //求交集
print(25, jedis.sismember(likeKey1, "12"));
print(26, jedis.sismember(likeKey2, "12"));
jedis.srem(likeKey1, "5"); //删掉5
print(27, jedis.smembers(likeKey1));
// 从1移动到2
jedis.smove(likeKey2, likeKey1, "14");
print(28, jedis.smembers(likeKey1));
print(29, jedis.scard(likeKey1)); //likeKey1中有多少个值
// 排序集合，优先队列，排行榜 zsort sorted set
String rankKey = "rankKey";
jedis.zadd(rankKey, 15, "Jim");
jedis.zadd(rankKey, 60, "Ben");
jedis.zadd(rankKey, 90, "Lee");
jedis.zadd(rankKey, 75, "Lucy");
jedis.zadd(rankKey, 80, "Mei");
print(30, jedis.zcard(rankKey));
print(31, jedis.zcount(rankKey, 61, 100));
// 改错卷了
print(32, jedis.zscore(rankKey, "Lucy"));
jedis.zincrby(rankKey, 2, "Lucy");
print(33, jedis.zscore(rankKey, "Lucy"));
jedis.zincrby(rankKey, 2, "Luc");
print(34, jedis.zscore(rankKey, "Luc"));
print(35, jedis.zcount(rankKey, 0, 100));
// 1-4 名 Luc
print(36, jedis.zrange(rankKey, 0, 10));
print(36, jedis.zrange(rankKey, 1, 3));
print(36, jedis.zrevrange(rankKey, 1, 3));
for (Tuple tuple : jedis.zrangeByScoreWithScores(rankKey, "0", "100")) {
print(37, tuple.getElement() + ":" + String.valueOf(tuple.getScore()));
}
print(38, jedis.zrank(rankKey, "Ben"));
print(39, jedis.zrevrank(rankKey, "Ben"));
String setKey = "zset";
jedis.zadd(setKey, 1, "a");
jedis.zadd(setKey, 1, "b");
jedis.zadd(setKey, 1, "c");
jedis.zadd(setKey, 1, "d");
jedis.zadd(setKey, 1, "e");
print(40, jedis.zlexcount(setKey, "-", "+"));
print(41, jedis.zlexcount(setKey, "(b", "[d"));
print(42, jedis.zlexcount(setKey, "[b", "[d"));
jedis.zrem(setKey, "b");
print(43, jedis.zrange(setKey, 0, 10));
jedis.zremrangeByLex(setKey, "(c", "+");
print(44, jedis.zrange(setKey, 0, 2));
/* jedis.lpush("aaa", "A"); jedis.lpush("aaa", "B"); jedis.lpush("aaa", "C"); print(45, jedis.brpop(0, "aaa")); print(45, jedis.brpop(0, "aaa")); print(45, jedis.brpop(0, "aaa")); */
//池子概念
JedisPool pool = new JedisPool();
for (int i = 0; i < 100; ++i) {
Jedis j = pool.getResource(); //默认8条线程
j.get("a");
j.close();
}
}
@Override
public void afterPropertiesSet() throws Exception {
//jedis = new Jedis("localhost");
pool = new JedisPool("localhost", 6379);
}
private Jedis getJedis() {
//return jedis;
return pool.getResource();
}
public String get(String key) {
Jedis jedis = null;
try {
jedis = pool.getResource();
return getJedis().get(key);
} catch (Exception e) {
logger.error("发生异常" + e.getMessage());
return null;
} finally {
if (jedis != null) {
jedis.close();
}
}
}
public void set(String key, String value) {
Jedis jedis = null;
try {
jedis = pool.getResource();
jedis.set(key, value);
} catch (Exception e) {
logger.error("发生异常" + e.getMessage());
} finally {
if (jedis != null) {
jedis.close();
}
}
}
public long sadd(String key, String value) { //将点赞用户的集合放进Redis的集合中
Jedis jedis = null;
try {
jedis = pool.getResource(); //从池里取一个
return jedis.sadd(key, value);
} catch (Exception e) {
logger.error("发生异常" + e.getMessage());
return 0;
} finally {
if (jedis != null) {
jedis.close();
}
}
}
public long srem(String key, String value) {
Jedis jedis = null;
try {
jedis = pool.getResource();
return jedis.srem(key, value);
} catch (Exception e) {
logger.error("发生异常" + e.getMessage());
return 0;
} finally {
if (jedis != null) {
jedis.close();
}
}
}
public boolean sismember(String key, String value) {
Jedis jedis = null;
try {
jedis = pool.getResource();
return jedis.sismember(key, value);
} catch (Exception e) {
logger.error("发生异常" + e.getMessage());
return false;
} finally {
if (jedis != null) {
jedis.close();
}
}
}
public long scard(String key) {
Jedis jedis = null;
try {
jedis = pool.getResource();
return jedis.scard(key);
} catch (Exception e) {
logger.error("发生异常" + e.getMessage());
return 0;
} finally {
if (jedis != null) {
jedis.close();
}
}
}
public void setex(String key, String value) {
// 验证码, 防机器注册，记录上次注册时间，有效期3天
Jedis jedis = null;
try {
jedis = pool.getResource();
jedis.setex(key, 10, value);
} catch (Exception e) {
logger.error("发生异常" + e.getMessage());
} finally {
if (jedis != null) {
jedis.close();
}
}
}
public long lpush(String key, String value) {
Jedis jedis = null;
try {
jedis = pool.getResource();
return jedis.lpush(key, value);
} catch (Exception e) {
logger.error("发生异常" + e.getMessage());
return 0;
} finally {
if (jedis != null) {
jedis.close();
}
}
}
public List<String> brpop(int timeout, String key) {
Jedis jedis = null;
try {
jedis = pool.getResource();
return jedis.brpop(timeout, key);
} catch (Exception e) {
logger.error("发生异常" + e.getMessage());
return null;
} finally {
if (jedis != null) {
jedis.close();
}
}
}
public void setObject(String key, Object obj) {
set(key, JSON.toJSONString(obj));
}
public <T> T getObject(String key, Class<T> clazz) {
String value = get(key);
if (value != null) {
return JSON.parseObject(value, clazz);
}
return null;
}
}