十. redis java client

 

    redis主页上列出的java 客户端有JDBC-Redis JRedis Jedis三种,下面分别介绍三种客户端的优缺点及其他相关的工具.

	支持redis版本	性能	维护	推荐
JDBC-Redis		not good
JRedis	1.2.n release 2.0.0 尚未release版本	fast
Jedis	2.0.0 release	fast	actively developed	推荐

 

JDBC-Redis

JDBC-Redis is just a JDBC wrapper for JRedis database.
If you plan on using your code with different back-ends then JDBC is a good way to go. NOTE: It is not a complete JDBC implementation and the NOSQL will bleed through.

If you are going to stay with Redis then I would suggest using the API, which will give you more flexibility. Use a DAO layer pattern to encapsulate your DB Access and down the road that is all you will need to change.

- Romain Hippeau

Redis syntax is completely different from standard SQL so using JDBC doesn't help encapsulating different back-ends as you suggest: I would have to write new queries anyway... – muriloq Jun 16 '10 at 14:00

@muriloq - but the mechanical acquiring and releasing resources is standard. – Romain Hippeau

 

 

spring wrapper

Spring provides a wrapper around both implementations(Jredis Jedis) and they're providing serialization/deserialization, amongst other things:

Person p = new Person("Joe", "Trader", 33);
template.convertAndSet("trader:1", p);
Person samePerson = template.getAndConvert("trader:1", Person.class);
Assert.assertEquals(p, samePerson);     

上面的方法可能已经调整,请参见最新的 http://static.springsource.org/spring-data/data-keyvalue/docs/1.0.0.M2/reference/html/#redis

放弃spring wrapper

项目中本来打算使用spring wrapper,出于以下原因最终还是放弃,直接使用Jedis,等有时间在把:

1.spring wrapper的版本是1.0.0.M2，里面有些bug (*)

2.对shard的支持没有jedis好

3.依赖spring3.0(主要是spring3.0 core中的convert及serializer),我们目前大多项目还是采用spring2.5.6(主要)

4.经过多层封装后性能还是会有损耗

spring nosql/cross-store

prototype implementation allowing entities to be stored in multiple types of data stores (i.e. JPA and Neo4j or JPA and Redis etc.)

 

JOhm

JOhm is a blazingly fast Object-Hash Mapping library for Java inspired by the awesome Ohm. The JOhm OHM is a modern-day avatar of the old ORM's like Hibernate with the difference being that we are not dealing with an RDBMS here but with a NoSQL rockstar.

homepage:https://github.com/xetorthio/johm

 

jedis pool的问题

在使用jedis pool时遇到了这个问题：It seems like server has closed the connection

原因分析：

1.redis server 关闭了此客户端的连接:server端设置了maxidletime(默认是5分钟），服务端会不断循环检测clinet的最后一次通信时间（lastinteraction），如果大于maxidletime，则关闭连接，并回收相关资源。client在向该连接中写数据后就会由于server端已经关闭而出现 broken pipe的问题。

2.pool的设置错误:

<bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig">
        <property name="maxActive"  value="20" />
        <property name="maxIdle" value="10" />
        <property name="maxWait" value="1000" />
    </bean>

<!-- jedis shard信息配置 -->
<bean id="jedis.shardInfo" class="redis.clients.jedis.JedisShardInfo">
<constructor-arg index="0" value="*.*.*.*" />
<constructor-arg index="1" value="6379" />
</bean>

<!-- jedis shard pool配置 -->
<bean id="shardedJedisPool" class="redis.clients.jedis.ShardedJedisPool">
<constructor-arg index="0" ref="jedisPoolConfig" />
<constructor-arg index="1">
<list>
<ref bean="jedis.shardInfo" />
</list>
</constructor-arg>
</bean>

<bean id="jedisCommands" factory-bean="shardedJedisPool"
factory-method="getResource" />

上面的这种配法在spring初始化时获取一次实例化jedisCommands，而后每次的redis的调用时并未从pool中获取

解决方案：

设置

<!-- POOL配置 -->
    <bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig">
        <property name="maxActive"  value="20" />
        <property name="maxIdle" value="10" />
        <property name="maxWait" value="1000" />
        <property name="testOnBorrow"  value="true"/>
    </bean>

    <!-- jedis shard信息配置 -->
    <bean id="jedis.shardInfo" class="redis.clients.jedis.JedisShardInfo">
        <constructor-arg index="0" value="*.*.*.*" />
        <constructor-arg index="1" value="6379" />
    </bean>

    <!-- jedis shard pool配置 -->
    <bean id="shardedJedisPool" class="redis.clients.jedis.ShardedJedisPool">
        <constructor-arg index="0" ref="jedisPoolConfig" />
        <constructor-arg index="1">
            <list>
                <ref bean="jedis.shardInfo" />
            </list>
        </constructor-arg>
    </bean>

参考:
http://stackoverflow.com/questions/3047010/best-redis-library-for-java
https://github.com/xetorthio/johm

https://github.com/xetorthio/jedis/issues/closed#issue/76