Jedis的基本使用

前言

Redis在Java’中的客户端在GitHub上start最高的是Jedis和Redisson。Jedis提供了完整的Redis命令，而Redisson有更多分布式的容器实现

如何使用Jedis

1.导入依赖

首先通过Maven引入Jedis的依赖

<dependency><groupId>redis.clients</groupId><artifactId>jedis</artifactId><version>2.8.0</version>
</dependency>

2.创建Jedis对象

 Jedis jedis = new Jedis("localhost", 6379);jedis.set("singleJedis", "hello jedis!");System.out.println(jedis.get("singleJedis"));jedis.close();

Jedis对象不是线程安全的，在多线程下使用同一个Jedis对象会出现并发问题，为了避免每次使用Jedis对象时都需要重新创建，Jedis提供了JedisPool。Jedis是线程安全的连接池

3.配置属性文件

#redis config start
redis.ip=127.0.0.1
redis.port=6379#最大连接数
redis.max.total=20#最大空闲数
redis.max.idle=10#最小空闲数
redis.min.idle=2#从jedis连接池获取连接时，校验并返回可用的连接
redis.test.borrow=true#把连接放回jedis连接池时，校验并返回可用的连接
redis.test.return=true

4.JedisPool

public class RedisPool {private static JedisPool pool;//jedis连接池private static Integer maxTotal = Integer.parseInt(PropertiesUtil.getProperty("redis.max.total","20")); //最大连接数private static Integer maxIdle = Integer.parseInt(PropertiesUtil.getProperty("redis.max.idle","20"));//在jedispool中最大的idle状态(空闲的)的jedis实例的个数private static Integer minIdle = Integer.parseInt(PropertiesUtil.getProperty("redis.min.idle","20"));//在jedispool中最小的idle状态(空闲的)的jedis实例的个数private static Boolean testOnBorrow = Boolean.parseBoolean(PropertiesUtil.getProperty("redis.test.borrow","true"));//在borrow一个jedis实例的时候，是否要进行验证操作，如果赋值true。则得到的jedis实例肯定是可以用的。private static Boolean testOnReturn = Boolean.parseBoolean(PropertiesUtil.getProperty("redis.test.return","true"));//在return一个jedis实例的时候，是否要进行验证操作，如果赋值true。则放回jedispool的jedis实例肯定是可以用的。private static String redisIp = PropertiesUtil.getProperty("redis.ip");private static Integer redisPort = Integer.parseInt(PropertiesUtil.getProperty("redis.port"));private static void initPool(){JedisPoolConfig config = new JedisPoolConfig();config.setMaxTotal(maxTotal);config.setMaxIdle(maxIdle);config.setMinIdle(minIdle);config.setTestOnBorrow(testOnBorrow);config.setTestOnReturn(testOnReturn);config.setBlockWhenExhausted(true);//连接耗尽的时候，是否阻塞，false会抛出异常，true阻塞直到超时。默认为true。pool = new JedisPool(config,redisIp,redisPort,1000*2);}//静态代码块，初始化Redis池static{initPool();}public static Jedis getJedis(){return pool.getResource();}public static void returnBrokenResource(Jedis jedis){pool.returnBrokenResource(jedis);}public static void returnResource(Jedis jedis){pool.returnResource(jedis);}}

5.封装Jedis

@Slf4j
public class RedisPoolUtil {/*** 设置key的有效期，单位是秒* @param key* @param exTime* @return*/public static Long expire(String key,int exTime){Jedis jedis = null;Long result = null;try {//从Redis连接池中获得Jedis对象jedis = RedisPool.getJedis();//设置成功则返回Jedis对象result = jedis.expire(key,exTime);} catch (Exception e) {log.error("expire key:{} error",key,e);RedisPool.returnBrokenResource(jedis);return result;}RedisPool.returnResource(jedis);return result;}//exTime的单位是秒//设置key-value并且设置超时时间public static String setEx(String key,String value,int exTime){Jedis jedis = null;String result = null;try {jedis = RedisPool.getJedis();result = jedis.setex(key,exTime,value);} catch (Exception e) {log.error("setex key:{} value:{} error",key,value,e);RedisPool.returnBrokenResource(jedis);return result;}RedisPool.returnResource(jedis);return result;}public static String set(String key,String value){Jedis jedis = null;String result = null;try {jedis = RedisPool.getJedis();result = jedis.set(key,value);} catch (Exception e) {log.error("set key:{} value:{} error",key,value,e);RedisPool.returnBrokenResource(jedis);return result;}RedisPool.returnResource(jedis);return result;}public static String get(String key){Jedis jedis = null;String result = null;try {jedis = RedisPool.getJedis();result = jedis.get(key);} catch (Exception e) {log.error("get key:{} error",key,e);RedisPool.returnBrokenResource(jedis);return result;}RedisPool.returnResource(jedis);return result;}public static Long del(String key){Jedis jedis = null;Long result = null;try {jedis = RedisPool.getJedis();result = jedis.del(key);} catch (Exception e) {log.error("del key:{} error",key,e);RedisPool.returnBrokenResource(jedis);return result;}RedisPool.returnResource(jedis);return result;}

SharedJedis

为了提高应用的性能，我们通常不止使用一台Redis做缓存服务，而在Redis2.x版本中并没有支持集群，Redis从3.x版本才开始支持集群。Redis2.x版本下实现Redis服务器的扩展需要通过横向扩展的方式，即多个相互独立的主从服务器群，使用SharedJedis实现分布式缓存，SharedJedis通过一致性哈希来实现分布式缓存，即实现一定的策略将不同的key分配到不同的Redis Server上，达到横向扩展的目的

1.RedisSharedPool

public class RedisShardedPool {private static ShardedJedisPool pool;//sharded jedis连接池private static Integer maxTotal = Integer.parseInt(PropertiesUtil.getProperty("redis.max.total","20")); //最大连接数private static Integer maxIdle = Integer.parseInt(PropertiesUtil.getProperty("redis.max.idle","20"));//在jedispool中最大的idle状态(空闲的)的jedis实例的个数private static Integer minIdle = Integer.parseInt(PropertiesUtil.getProperty("redis.min.idle","20"));//在jedispool中最小的idle状态(空闲的)的jedis实例的个数private static Boolean testOnBorrow = Boolean.parseBoolean(PropertiesUtil.getProperty("redis.test.borrow","true"));//在borrow一个jedis实例的时候，是否要进行验证操作，如果赋值true。则得到的jedis实例肯定是可以用的。private static Boolean testOnReturn = Boolean.parseBoolean(PropertiesUtil.getProperty("redis.test.return","true"));//在return一个jedis实例的时候，是否要进行验证操作，如果赋值true。则放回jedispool的jedis实例肯定是可以用的。//获取Redis1相关信息private static String redis1Ip = PropertiesUtil.getProperty("redis1.ip");private static Integer redis1Port = Integer.parseInt(PropertiesUtil.getProperty("redis1.port"));//获取Redis2的相关信息private static String redis2Ip = PropertiesUtil.getProperty("redis2.ip");private static Integer redis2Port = Integer.parseInt(PropertiesUtil.getProperty("redis2.port"));private static void initPool(){JedisPoolConfig config = new JedisPoolConfig();config.setMaxTotal(maxTotal);config.setMaxIdle(maxIdle);config.setMinIdle(minIdle);config.setTestOnBorrow(testOnBorrow);config.setTestOnReturn(testOnReturn);config.setBlockWhenExhausted(true);//连接耗尽的时候，是否阻塞，false会抛出异常，true阻塞直到超时。默认为true。JedisShardInfo info1 = new JedisShardInfo(redis1Ip,redis1Port,1000*2);JedisShardInfo info2 = new JedisShardInfo(redis2Ip,redis2Port,1000*2);//创建一个JedisListList<JedisShardInfo> jedisShardInfoList = new ArrayList<JedisShardInfo>(2);jedisShardInfoList.add(info1);jedisShardInfoList.add(info2);//RedisSharedPool传入JedisListpool = new ShardedJedisPool(config,jedisShardInfoList, Hashing.MURMUR_HASH, Sharded.DEFAULT_KEY_TAG_PATTERN);}static{initPool();}public static ShardedJedis getJedis(){return pool.getResource();}public static void returnBrokenResource(ShardedJedis jedis){pool.returnBrokenResource(jedis);}public static void returnResource(ShardedJedis jedis){pool.returnResource(jedis);}}

2.封装ShraedJedis

@Slf4j
public class RedisShardedPoolUtil {/*** 设置key的有效期，单位是秒* @param key* @param exTime* @return*/public static Long expire(String key,int exTime){ShardedJedis jedis = null;Long result = null;try {//根据SharedJedis的一致性哈希策略从对应的Redis Server获取值或设置值jedis = RedisShardedPool.getJedis();result = jedis.expire(key,exTime);} catch (Exception e) {log.error("expire key:{} error",key,e);RedisShardedPool.returnBrokenResource(jedis);return result;}RedisShardedPool.returnResource(jedis);return result;}//exTime的单位是秒public static String setEx(String key,String value,int exTime){ShardedJedis jedis = null;String result = null;try {jedis = RedisShardedPool.getJedis();result = jedis.setex(key,exTime,value);} catch (Exception e) {log.error("setex key:{} value:{} error",key,value,e);RedisShardedPool.returnBrokenResource(jedis);return result;}RedisShardedPool.returnResource(jedis);return result;}public static String set(String key,String value){ShardedJedis jedis = null;String result = null;try {jedis = RedisShardedPool.getJedis();result = jedis.set(key,value);} catch (Exception e) {log.error("set key:{} value:{} error",key,value,e);RedisShardedPool.returnBrokenResource(jedis);return result;}RedisShardedPool.returnResource(jedis);return result;}public static String getSet(String key,String value){ShardedJedis jedis = null;String result = null;try {jedis = RedisShardedPool.getJedis();result = jedis.getSet(key,value);} catch (Exception e) {log.error("getset key:{} value:{} error",key,value,e);RedisShardedPool.returnBrokenResource(jedis);return result;}RedisShardedPool.returnResource(jedis);return result;}public static String get(String key){ShardedJedis jedis = null;String result = null;try {jedis = RedisShardedPool.getJedis();result = jedis.get(key);} catch (Exception e) {log.error("get key:{} error",key,e);RedisShardedPool.returnBrokenResource(jedis);return result;}RedisShardedPool.returnResource(jedis);return result;}public static Long del(String key){ShardedJedis jedis = null;Long result = null;try {jedis = RedisShardedPool.getJedis();result = jedis.del(key);} catch (Exception e) {log.error("del key:{} error",key,e);RedisShardedPool.returnBrokenResource(jedis);return result;}RedisShardedPool.returnResource(jedis);return result;}public static Long setnx(String key,String value){ShardedJedis jedis = null;Long result = null;try {jedis = RedisShardedPool.getJedis();result = jedis.setnx(key,value);} catch (Exception e) {log.error("setnx key:{} value:{} error",key,value,e);RedisShardedPool.returnBrokenResource(jedis);return result;}RedisShardedPool.returnResource(jedis);return result;}
}

除了初始化SharedJedisPool时需要加入多个Redis服务器信息外，其他和Jedis差不多

Shared一致性哈希实现

shared一致性哈希实现采用以下方案：
Redis服务器节点划分：将每台服务器节点采用hash算法划分为160个虚拟节点(可以配置划分权重)

将划分的虚拟节点采用TreeMap存储
对每个Redis服务器的物理连接采用LinkedHashMap存储
对Key or KeyTag 采用同样的hash算法，然后从TreeMap获取大于等于键hash值得节点，取最邻近节点存储；当key的hash值大于虚拟节点hash值得最大值时，存入第一个虚拟节点

sharded采用的hash算法：MD5 和 MurmurHash两种；默认采用64位的MurmurHash算法；MurmurHash是一种高效，低碰撞的hash算法