使用redis存储对象或集合时，不能直接存储。需要将对象或集

合通过序列化转换为可存储的json，这里使用了fastjson来转型

redis是一个key-value存储系统。和Memcached类似，它支持存储的value类型相对更多，包括string(字符串)、list(链表)、set(集合)、

zset(sorted set --有序集合)和hash（哈希类型）

所用到的依赖,可以在maven仓库中查找

<!-- redis客户端:Jedis -->
<dependency><groupId>redis.clients</groupId><artifactId>jedis</artifactId><version>2.7.3</version>
</dependency>

<!-- https://mvnrepository.com/artifact/net.sf.json-lib/json-lib -->
<dependency><groupId>net.sf.json-lib</groupId><artifactId>json-lib</artifactId><version>2.4</version>
</dependency>

1.redis工具类，里面写了部分redis常用命令

package com.bcc.util;import java.util.List;
import java.util.Map;
import java.util.Set;import org.apache.commons.lang.StringUtils;import com.fasterxml.jackson.databind.ObjectMapper;import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;
import redis.clients.util.SafeEncoder;public class jedisUtil {private static String HOST = "localhost";private static int PORT = 6379;private static JedisPool pool = null;static {JedisPoolConfig config = new JedisPoolConfig();config.setMaxTotal(128);config.setMaxIdle(80);config.setMaxWaitMillis(2001);pool = new JedisPool(config, HOST, PORT, 2000);}/*** 把key存入redis中** @param key     k* @param value   v* @param seconds 过期时间（秒）* @return boolean*/public static boolean set(byte[] key, byte[] value, int seconds) {Jedis jedis = null;try {jedis = pool.getResource();String result = jedis.set(key, value);if (seconds > 0) {Long r = jedis.expire(key, seconds);}} catch (Exception e) {return false;} finally {if (null != jedis) {jedis.close();}}return true;}public static byte[] get(byte[] key) {byte[] value = null;Jedis jedis = null;try {jedis = pool.getResource();value = jedis.get(key);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return value;}/*** 向缓存中设置对象** @param key key* @param obj value* @return boolean*/public static boolean set(String key, Object obj, Integer seconds) {Jedis jedis = null;try {jedis = pool.getResource();ObjectMapper mapper = new ObjectMapper();String value = mapper.writeValueAsString(obj);jedis.set(SafeEncoder.encode(key), SafeEncoder.encode(value));if (seconds != null) {jedis.expire(key, seconds);}return true;} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return false;}/*** 向缓存中设置对象** @param key   key* @param value value* @return boolean*/public static boolean set(String key, String value, Integer seconds) {Jedis jedis = null;try {jedis = pool.getResource();jedis.set(SafeEncoder.encode(key), SafeEncoder.encode(value));if (seconds != null) {jedis.expire(key, seconds);}return true;} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return false;}/*** 移除缓存中设置对象** @param keys 被删除的KEYS* @return Long 被删除个数*/public static Long del(String... keys) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.del(keys);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}/*** 根据key 获取对象** @param key key* @return T*/public static <T> T get(String key, Class<T> clazz) {Jedis jedis = null;try {jedis = pool.getResource();String v = jedis.get(key);if (StringUtils.isNotEmpty(v)) {ObjectMapper mapper = new ObjectMapper();return mapper.readValue(v, clazz);}} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}/*** 根据key值得到String类型的返回值** @param key key* @return String*/public static String get(String key) {Jedis jedis = null;try {jedis = pool.getResource();String v = jedis.get(key);if (StringUtils.isNotEmpty(v)) {return v;}} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}public static Boolean exists(String key) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.exists(key);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}/*** redis的list操作：* 把元素插入到列表的尾部** @param key     KEY* @param strings 要插入的值，变参* @return 返回插入后list的大小*/public static Long rpush(String key, String... strings) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.rpush(key, strings);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}/*** redis的list操作：* 根据开始与结束下标取list中的值** @param key   KEY* @param start 开始下标* @param end   结束下标* @return List<String>*/public static List<String> lrange(String key, int start, int end) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.lrange(key, start, end);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}/*** redis的list操作：* 取列表的长度** @param key key* @return Long*/public static Long llen(String key) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.llen(key);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}/*** redis的list操作：* 根据值移除list中的元素** @param key   KEY* @param count ：*              count > 0 : 从表头开始向表尾搜索，移除与 value 相等的元素，数量为 count 。*              count < 0 : 从表尾开始向表头搜索，移除与 value 相等的元素，数量为 count 的绝对值。*              count = 0 : 移除表中所有与 value 相等的值。* @param value 要删除的值* @return 返回被移除的个数*/public static Long lrem(String key, long count, String value) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.lrem(key, count, value);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}public static boolean setLong(String key, Long value) {Jedis jedis = null;try {jedis = pool.getResource();return "OK".equals(jedis.set(key, String.valueOf(value)));} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return false;}public static Long getLong(String key) {String result = get(key);return result == null ? null : Long.valueOf(result);}public static Long incrBy(String key, Long increment) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.incrBy(key, increment);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}public static Long hashSet(String key, String field, String value) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.hset(key, field, value);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return -1L;}public static Long hashSetLong(String key, String field, Long value) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.hset(key, field, String.valueOf(value));} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return -1L;}public static Long hashIncrBy(String key, String field, Long increment) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.hincrBy(key, field, increment);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return -1L;}public static Map<String, String> hashGetAll(String key) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.hgetAll(key);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}public static Set<String> hashKeys(String key) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.hkeys(key);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}public static Long hashDelAll(String key, String... fields) {Jedis jedis = null;try {jedis = pool.getResource();return jedis.hdel(key, fields);} catch (Exception e) {} finally {if (null != jedis) {jedis.close();}}return null;}
}

2.实现类中调用

package com.bcc.service;import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.bcc.dao.usermapper;
import com.bcc.pojo.City;
import com.bcc.util.jedisUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.util.List;@Service
public class userserviceimpl implements userservice{@Autowiredprivate usermapper um;//这里展示一个简单的查询方法，返回的是list集合，把list集合存入redis@Overridepublic List<City> listCity(String sname) {//首先先判断redis中是否存在该key值String aa1 = jedisUtil.get("aoo");if (aa1==null){ //若不存在首先走一下方法，从数据库中查询数据List<City> cities  = um.listCity(sname);//然后调用JSON.toJSONString()方法转为jsonString ss = JSON.toJSONString(cities);//存入redisjedisUtil.set("aoo", ss, 10000*100000);return cities;}else {//若存在，将key值查询出来，此时的key值还是json形式String aoo = jedisUtil.get("aoo");//调用JSON.parseArray()方法转为list集合List<City> cities = JSON.parseArray(aoo,City.class);//JSON.parseObject方法是转为对象/*City city = JSON.parseObject(aoo, City.class);*/return cities;}}
}

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使用redis存储对象或集合时，不能直接存储。需要将对象或集

合通过序列化转换为可存储的json，这里使用了fastjson来转型

1.redis工具类，里面写了部分redis常用命令

2.实现类中调用

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