Redis Java客户端Jedis

2019-11-08 20:37:22

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目前Redis基于java语言的Client：

Jredis：https://github.com/alphazero/jredisJedis：https://github.com/xetorthio/jedisRedis4J：https://github.com/guming/redis4j

Jedis是官方提供的唯一Redis Client For Java PRovider。

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<dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.6.2</version> </dependency>

一、Jedis简单使用

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package cn.slimsmart.redis.demo.jedis; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; import redis.clients.jedis.Jedis; @SuppressWarnings("resource") public class JedisTest { private static final String HASH_KEY = "key"; public static void main(String[] args) { Jedis jedis = new Jedis("192.168.36.189", 6379); /** * 存储String key-value */ jedis.set(HASH_KEY, "value"); /** * 如果已经存在key了，先删除掉 */ if (jedis.exists(HASH_KEY)) { System.out.println(jedis.get(HASH_KEY)); jedis.del(HASH_KEY); } /** * 存入单个key-value */ jedis.hset(HASH_KEY, "username", "yourUsername"); /** * 存入多个key-value键值对 */ Map<String, String> keyValueMap = new HashMap<String, String>(); keyValueMap.put("passWord", "YourPassword"); keyValueMap.put("age", "20"); jedis.hmset(HASH_KEY, keyValueMap); /** * 判断某个key是否在指定的Hash key中 */ boolean existsUsernameKey = jedis.hexists(HASH_KEY, "username"); // true System.out.println(existsUsernameKey); /** * 获取某个hash中键值对的数量 */ Long len = jedis.hlen(HASH_KEY); // 3 System.out.println(len); /** * 获取一个hash中的所有key */ Set<String> keys = jedis.hkeys(HASH_KEY); // [password, username, age] System.out.println(keys); /** * 获取一个hash中的所有values */ List<String> values = jedis.hvals(HASH_KEY); // [yourUsername, YourPassword, 20] System.out.println(values); /** * 获取指定hash的所有的键值对 */ Map<String, String> allKVMap = jedis.hgetAll(HASH_KEY); // {username=yourUsername, age=20, password=YourPassword} System.out.println(allKVMap); /** * 从一个hash中获取某个field的值 */ String value = jedis.hget(HASH_KEY, "username"); // yourUsername System.out.println(value); List<String> multValues = jedis.hmget(HASH_KEY, "username", "password"); // [yourUsername, YourPassword] System.out.println(multValues); } } 二、连接池的使用

Jedis使用commons-pool完成池化实现。1.配置文件redis.properties

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redis.pool.maxTotal=10 redis.pool.minIdle=2 redis.pool.maxIdle=10 redis.pool.maxWait=1000 redis.pool.testWhileIdle=true redis.pool.testOnBorrow=true redis.pool.testOnReturn=true #ip redis.ip=192.168.36.189 #Port redis.port=6379 2.实例代码

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package cn.slimsmart.redis.demo.jedis; import java.util.ResourceBundle; import redis.clients.jedis.Jedis; import redis.clients.jedis.JedisPool; import redis.clients.jedis.JedisPoolConfig; public class JedisPoolTest { public static void main(String[] args) { ResourceBundle bundle = ResourceBundle.getBundle("redis"); if (bundle == null) { throw new IllegalArgumentException("[redis.properties] is not found!"); } JedisPoolConfig config = new JedisPoolConfig(); config.setMaxTotal(Integer.valueOf(bundle.getString("redis.pool.maxTotal"))); config.setMinIdle(Integer.valueOf(bundle.getString("redis.pool.minIdle"))); config.setMaxIdle(Integer.valueOf(bundle.getString("redis.pool.maxIdle"))); config.setMaxWaitMillis(Long.valueOf(bundle.getString("redis.pool.maxWait"))); config.setTestWhileIdle(Boolean.valueOf(bundle.getString("redis.pool.testWhileIdle"))); config.setTestOnBorrow(Boolean.valueOf(bundle.getString("redis.pool.testOnBorrow"))); config.setTestOnReturn(Boolean.valueOf(bundle.getString("redis.pool.testOnReturn"))); JedisPool pool = new JedisPool(config, bundle.getString("redis.ip"), Integer.valueOf(bundle.getString("redis.port"))); // 从池中获取一个Jedis对象 Jedis jedis = pool.getResource(); String key = "key"; // 删数据 jedis.del(key); // 存数据 jedis.set(key, "abc123"); // 取数据 String value = jedis.get(key); System.out.println(value); // 释放对象池 pool.returnResource(jedis); } } 三、一致性哈希

Memcached完全基于分布式集群，而Redis是Master-Slave，如果想把Reids，做成集群模式，无外乎多做几套Master-Slave，每套Master-Slave完成各自的容灾处理，通过Client工具，完成一致性哈希。Memcached是在Server端完成Sharding，Redis只能依靠各个Client做Sharding。在Redis%203.0系列支持Server端Sharding。

shared一致性哈希采用以下方案：1.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)2.将划分虚拟节点采用TreeMap存储3.对每个Redis服务器的物理连接采用LinkedHashMap存储4.对Key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。

1.配置文件redis.properties

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redis.pool.maxTotal=10 redis.pool.minIdle=2 redis.pool.maxIdle=10 redis.pool.maxWait=1000 redis.pool.testWhileIdle=true redis.pool.testOnBorrow=true redis.pool.testOnReturn=true #IP redis1.ip=192.168.36.189 redis2.ip=192.168.36.54 #Port redis.port=6379 2.实例代码

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package cn.slimsmart.redis.demo.jedis; import java.util.LinkedList; import java.util.List; import java.util.ResourceBundle; import redis.clients.jedis.JedisPoolConfig; import redis.clients.jedis.JedisShardInfo; import redis.clients.jedis.ShardedJedis; import redis.clients.jedis.ShardedJedisPool; public class JedisShardInfoTest { public static void main(String[] args) { ResourceBundle bundle = ResourceBundle.getBundle("redis"); if (bundle == null) { throw new IllegalArgumentException("[redis.properties] is not found!"); } JedisPoolConfig config = new JedisPoolConfig(); config.setMaxTotal(Integer.valueOf(bundle.getString("redis.pool.maxTotal"))); config.setMinIdle(Integer.valueOf(bundle.getString("redis.pool.minIdle"))); config.setMaxIdle(Integer.valueOf(bundle.getString("redis.pool.maxIdle"))); config.setMaxWaitMillis(Long.valueOf(bundle.getString("redis.pool.maxWait"))); config.setTestWhileIdle(Boolean.valueOf(bundle.getString("redis.pool.testWhileIdle"))); config.setTestOnBorrow(Boolean.valueOf(bundle.getString("redis.pool.testOnBorrow"))); config.setTestOnReturn(Boolean.valueOf(bundle.getString("redis.pool.testOnReturn"))); JedisShardInfo jedisShardInfo1 = new JedisShardInfo(bundle.getString("redis1.ip"), Integer.valueOf(bundle.getString("redis.port"))); JedisShardInfo jedisShardInfo2 = new JedisShardInfo(bundle.getString("redis2.ip"), Integer.valueOf(bundle.getString("redis.port"))); List<JedisShardInfo> list = new LinkedList<JedisShardInfo>(); list.add(jedisShardInfo1); list.add(jedisShardInfo2); // 初始化ShardedJedisPool代替JedisPool ShardedJedisPool pool = new ShardedJedisPool(config, list); // 从池中获取一个Jedis对象 ShardedJedis jedis = pool.getResource(); String keys = "key"; String value = "abc123"; // 删数据 jedis.del(keys); // 存数据 jedis.set(keys, value); // 取数据 String v = jedis.get(keys); System.out.println(v); // 释放对象池 pool.returnResource(jedis); } } 通过以上方式，向redis进行set操作的key-value，会通过hash而均匀的分配到pool里的redis机器中。

四、spring集成

如果有必要，可以用Spring封装初始化。

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<context:property-placeholder location="classpath:redis.properties" /> <bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig"> <property name="maxTotal" value="${redis.pool.maxTotal}" /> <property name="minIdle" value="${redis.pool.minIdle}" /> <property name="maxIdle" value="${redis.pool.maxIdle}" /> <property name="maxWait" value="${redis.pool.maxWait}" /> <property name="testWhileIdle" value="${redis.pool.testWhileIdle}" /> <property name="testOnBorrow" value="${redis.pool.testOnBorrow}" /> <property name="testOnReturn" value="${redis.pool.testOnReturn}" /> </bean> <bean id="shardedJedisPool" class="redis.clients.jedis.ShardedJedisPool"> <constructor-arg index="0" ref="jedisPoolConfig" /> <constructor-arg index="1"> <list> <bean class="redis.clients.jedis.JedisShardInfo"> <constructor-arg index="0" value="${redis1.ip}" /> <constructor-arg index="1" value="${redis.port}" type="int" /> </bean> <bean class="redis.clients.jedis.JedisShardInfo"> <constructor-arg index="0" value="${redis2.ip}" /> <constructor-arg index="1" value="${redis.port}" type="int" /> </bean> </list> </constructor-arg> </bean> 当然，Spring提供了对于Redis的专门支持：spring-data-redis。

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