Redis实战之Redis + Jedis

言归正传，目前Redis大概有3中基于Java语言的Client：

Jredis
Jedis
Redis4J

这里只说Jedis，因为它是官方提供的唯一Redis Client For Java Provider！

一、简单使用Jedis

需要Jedis就从Maven获取吧！

Maven Pom.xml

Xml代码



<dependency>

<groupId>redis.clients</groupId>

<artifactId>jedis</artifactId>

<version>2.1.0</version>

<type>jar</type>

<scope>compile</scope>

</dependency>

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<dependency>

<groupId>redis.clients</groupId>

<artifactId>jedis</artifactId>

<version>2.1.0</version>

<type>jar</type>

<scope>compile</scope>

</dependency>

如果只是简单使用Jedis，以下这么几行代码足够：

Java代码



Jedis jedis = new Jedis("10.11.20.140");

String keys = "name";

// 删数据

jedis.del(keys);

// 存数据

jedis.set(keys, "snowolf");

// 取数据

String value = jedis.get(keys);

System.out.println(value);

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Jedis jedis = new Jedis("10.11.20.140");

String keys = "name";

// 删数据

jedis.del(keys);

// 存数据

jedis.set(keys, "snowolf");

// 取数据

String value = jedis.get(keys);

System.out.println(value);

二、池化使用Jedis

Jedis使用commons-pool完成池化实现。

先做个配置文件：

Properties代码



#最大分配的对象数

redis.pool.maxActive=1024

#最大能够保持idel状态的对象数

redis.pool.maxIdle=200

#当池内没有返回对象时，最大等待时间

redis.pool.maxWait=1000

#当调用borrow Object方法时，是否进行有效性检查

redis.pool.testOnBorrow=true

#当调用return Object方法时，是否进行有效性检查

redis.pool.testOnReturn=true

#IP

redis.ip=10.11.20.140

#Port

redis.port=6379

在静态代码段中完成初始化：

Java代码

private static JedisPool pool;

static {

ResourceBundle bundle = ResourceBundle.getBundle("redis");

if (bundle == null) {

throw new IllegalArgumentException(

"[redis.properties] is not found!");

}

JedisPoolConfig config = new JedisPoolConfig();

config.setMaxActive(Integer.valueOf(bundle

.getString("redis.pool.maxActive")));

config.setMaxIdle(Integer.valueOf(bundle

.getString("redis.pool.maxIdle")));

config.setMaxWait(Long.valueOf(bundle.getString("redis.pool.maxWait")));

config.setTestOnBorrow(Boolean.valueOf(bundle

.getString("redis.pool.testOnBorrow")));

config.setTestOnReturn(Boolean.valueOf(bundle

.getString("redis.pool.testOnReturn")));

pool = new JedisPool(config, bundle.getString("redis.ip"),

Integer.valueOf(bundle.getString("redis.port")));

}

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private static JedisPool pool;

static {

ResourceBundle bundle = ResourceBundle.getBundle("redis");

if (bundle == null) {

throw new IllegalArgumentException(

"[redis.properties] is not found!");

}

JedisPoolConfig config = new JedisPoolConfig();

config.setMaxActive(Integer.valueOf(bundle

.getString("redis.pool.maxActive")));

config.setMaxIdle(Integer.valueOf(bundle

.getString("redis.pool.maxIdle")));

config.setMaxWait(Long.valueOf(bundle.getString("redis.pool.maxWait")));

config.setTestOnBorrow(Boolean.valueOf(bundle

.getString("redis.pool.testOnBorrow")));

config.setTestOnReturn(Boolean.valueOf(bundle

.getString("redis.pool.testOnReturn")));

pool = new JedisPool(config, bundle.getString("redis.ip"),

Integer.valueOf(bundle.getString("redis.port")));

}

然后，修改前面那段jedis操作Redis

Java代码

// 从池中获取一个Jedis对象

Jedis jedis = pool.getResource();

String keys = "name";

// 删数据

jedis.del(keys);

// 存数据

jedis.set(keys, "snowolf");

// 取数据

String value = jedis.get(keys);

System.out.println(value);

// 释放对象池

pool.returnResource(jedis);

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// 从池中获取一个Jedis对象

Jedis jedis = pool.getResource();

String keys = "name";

// 删数据

jedis.del(keys);

// 存数据

jedis.set(keys, "snowolf");

// 取数据

String value = jedis.get(keys);

System.out.println(value);

// 释放对象池

pool.returnResource(jedis);

改为从对象池中，获取Jedis实例：

Java代码

// 从池中获取一个Jedis对象

Jedis jedis = pool.getResource();

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// 从池中获取一个Jedis对象

Jedis jedis = pool.getResource();

切记，最后使用后，释放Jedis对象：

Java代码

// 释放对象池

pool.returnResource(jedis);

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// 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。

PS:Memcached是在Server端完成Sharding，Redis只能依靠各个Client做Sharding。可能会在Redis 3.0系列支持Server端Sharding。

保留前面的JedisPoolConfig，新增两个Redis的IP（redis1.ip，redis2.ip），完成两个JedisShardInfo实例，并将其丢进List中：

Java代码

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);

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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：

Java代码

ShardedJedisPool pool = new ShardedJedisPool(config, list);

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ShardedJedisPool pool = new ShardedJedisPool(config, list);

改由ShardedJedis，获取Jedis对象：

Java代码

// 从池中获取一个Jedis对象

ShardedJedis jedis = pool.getResource();

String keys = "name";

String value = "snowolf";

// 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);

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// 从池中获取一个Jedi
4000
s对象

ShardedJedis jedis = pool.getResource();

String keys = "name";

String value = "snowolf";

// 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);

四、Spring封装参考

Ok，完成上述代码足够完成简单任务，如果有必要，可以用Spring封装初始化：

Xml代码

<context:property-placeholder location="classpath:redis.properties" />

<bean

id="jedisPoolConfig"

class="redis.clients.jedis.JedisPoolConfig"

>

<property

name="maxActive"

value="${redis.pool.maxActive}" />

<property

name="maxIdle"

value="${redis.pool.maxIdle}" />

<property

name="maxWait"

value="${redis.pool.maxWait}" />

<property

name="testOnBorrow"

value="${redis.pool.testOnBorrow}" />

</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>

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<context:property-placeholder location="classpath:redis.properties" />

<bean

id="jedisPoolConfig"

class="redis.clients.jedis.JedisPoolConfig"

>

<property

name="maxActive"

value="${redis.pool.maxActive}" />

<property

name="maxIdle"

value="${redis.pool.maxIdle}" />

<property

name="maxWait"

value="${redis.pool.maxWait}" />

<property

name="testOnBorrow"

value="${redis.pool.testOnBorrow}" />

</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>

代码可以更简洁一些：

Java代码

private ApplicationContext app;

private ShardedJedisPool pool;

@Before

public void before() throws Exception {

app = new ClassPathXmlApplicationContext("applicationContext.xml");

pool = (ShardedJedisPool) app.getBean("shardedJedisPool");

}

@Test

public void test() {

// 从池中获取一个Jedis对象

ShardedJedis jedis = pool.getResource();

String keys = "name";

String value = "snowolf";

// 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);

assertEquals(value, v);

}

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private ApplicationContext app;

private ShardedJedisPool pool;

@Before

public void before() throws Exception {

app = new ClassPathXmlApplicationContext("applicationContext.xml");

pool = (ShardedJedisPool) app.getBean("shardedJedisPool");

}

@Test

public void test() {

// 从池中获取一个Jedis对象

ShardedJedis jedis = pool.getResource();

String keys = "name";

String value = "snowolf";

// 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);

assertEquals(value, v);

}

当然，Spring提供了对于Redis的专门支持：spring-data-redis，以后有机会再深入研究。