大家在工作中可能会遇到这样的需求，即Redis读写分离，目的是为了压力分散化。下面我将为大家介绍借助AWS的ELB实现读写分离，以写主读从为例。

实现 引用库文件 <!-- redis客户端 --> <dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.6.2</version> </dependency> 方式一，借助切面 JedisPoolSelector

此类的目的是为读和写分别配置不同的注解，用来区分是主还是从。

package com.silence.spring.redis.readwriteseparation; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; /** * Created by keysilence on 16/10/26. */ @Retention(RetentionPolicy.RUNTIME) @Target(ElementType.METHOD) public @interface JedisPoolSelector { String value(); } JedisPoolAspect

此类的目的是针对主和从的注解，进行动态链接池调配，即主的使用主链接池，从的使用从连接池。

package com.silence.spring.redis.readwriteseparation; import org.aspectj.lang.JoinPoint; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.aspectj.lang.annotation.Pointcut; import org.aspectj.lang.reflect.MethodSignature; import org.springframework.beans.BeansException; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import redis.clients.jedis.JedisPool; import javax.annotation.PostConstruct; import java.lang.reflect.Method; import java.util.Date; /** * Created by keysilence on 16/10/26. */ @Aspect public class JedisPoolAspect implements ApplicationContextAware { private ApplicationContext ctx; @PostConstruct public void init() { System.out.println('jedis pool aspectj started @' + new Date()); } @Pointcut('execution(* com.silence.spring.redis.readwriteseparation.util.*.*(..))') private void allMethod() { } @Before('allMethod()') public void before(JoinPoint point) { Object target = point.getTarget(); String method = point.getSignature().getName(); Class classz = target.getClass(); Class<?>[] parameterTypes = ((MethodSignature) point.getSignature()) .getMethod().getParameterTypes(); try { Method m = classz.getMethod(method, parameterTypes); if (m != null && m.isAnnotationPresent(JedisPoolSelector.class)) { JedisPoolSelector data = m .getAnnotation(JedisPoolSelector.class); JedisPool jedisPool = (JedisPool) ctx.getBean(data.value()); DynamicJedisPoolHolder.putJedisPool(jedisPool); } } catch (Exception e) { e.printStackTrace(); } } public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { this.ctx = applicationContext; } } DynamicJedisPoolHolder

此类目的是存储当前使用的JedisPool，即上面类赋值后的结果保存。

package com.silence.spring.redis.readwriteseparation; import redis.clients.jedis.JedisPool; /** * Created by keysilence on 16/10/26. */ public class DynamicJedisPoolHolder { public static final ThreadLocal<JedisPool> holder = new ThreadLocal<JedisPool>(); public static void putJedisPool(JedisPool jedisPool) { holder.set(jedisPool); } public static JedisPool getJedisPool() { return holder.get(); } } RedisUtils

此类目的是对Redis具体的调用，里面包含使用主还是从的方式调用。

package com.silence.spring.redis.readwriteseparation.util; import com.silence.spring.redis.readwriteseparation.DynamicJedisPoolHolder; import com.silence.spring.redis.readwriteseparation.JedisPoolSelector; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Created by keysilence on 16/10/26. */ public class RedisUtils { private static Logger logger = LoggerFactory.getLogger(RedisUtils.class); @JedisPoolSelector('master') public String setString(final String key, final String value) { String ret = DynamicJedisPoolHolder.getJedisPool().getResource().set(key, value); System.out.println('key:' + key + ',value:' + value + ',ret:' + ret); return ret; } @JedisPoolSelector('slave') public String get(final String key) { String ret = DynamicJedisPoolHolder.getJedisPool().getResource().get(key); System.out.println('key:' + key + ',ret:' + ret); return ret; } } spring-datasource.xml <?xml version='1.0' encoding='UTF-8'?> <beans xmlns='' xmlns:xsi='' xmlns:aop='' xsi:schemaLocation=' http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop/spring-aop.xsd'> <bean id='poolConfig' class='redis.clients.jedis.JedisPoolConfig'> <!-- 池中最大链接数 --> <property name='maxTotal' value='100'/> <!-- 池中最大空闲链接数 --> <property name='maxIdle' value='50'/> <!-- 池中最小空闲链接数 --> <property name='minIdle' value='20'/> <!-- 当池中链接耗尽，调用者最大阻塞时间，超出此时间将跑出异常。（单位：毫秒；默认为-1，表示永不超时） --> <property name='maxWaitMillis' value='1000'/> <!-- 参考： --> <!-- 调用者获取链接时，是否检测当前链接有效性。无效则从链接池中移除，并尝试继续获取。（默认为false） --> <property name='testOnBorrow' value='true' /> <!-- 向链接池中归还链接时，是否检测链接有效性。（默认为false） --> <property name='testOnReturn' value='true' /> <!-- 调用者获取链接时，是否检测空闲超时。如果超时，则会被移除（默认为false） --> <property name='testWhileIdle' value='true' /> <!-- 空闲链接检测线程一次运行检测多少条链接 --> <property name='numTestsPerEvictionRun' value='10' /> <!-- 空闲链接检测线程检测周期。如果为负值，表示不运行检测线程。（单位：毫秒，默认为-1） --> <property name='timeBetweenEvictionRunsMillis' value='60000' /> <!-- 链接获取方式。队列：false；栈：true --> <!--<property name='lifo' value='false' />--> </bean> <bean id='master' class='redis.clients.jedis.JedisPool'> <constructor-arg index='0' ref='poolConfig'/> <constructor-arg index='1' value='192.168.100.110' type='java.lang.String'/> <constructor-arg index='2' value='6379' type='int'/> </bean> <bean id='slave' class='redis.clients.jedis.JedisPool'> <constructor-arg index='0' ref='poolConfig'/> <!-- 此处Host配置成ELB地址 --> <constructor-arg index='1' value='192.168.100.110' type='java.lang.String'/> <constructor-arg index='2' value='6380' type='int'/> </bean> <bean id='redisUtils' class='com.silence.spring.redis.readwriteseparation.util.RedisUtils'> </bean> <bean id='jedisPoolAspect' class='com.silence.spring.redis.readwriteseparation.JedisPoolAspect' /> <aop:aspectj-autoproxy proxy-target-class='true'/> </beans> Test package com.silence.spring.redis.readwriteseparation; import com.silence.spring.redis.readwriteseparation.util.RedisUtils; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; /** * Created by keysilence on 16/10/26. */ public class Test { public static void main(String[] args) { ApplicationContext ctx = new ClassPathXmlApplicationContext('spring-datasource.xml'); System.out.println(ctx); RedisUtils redisUtils = (RedisUtils) ctx.getBean('redisUtils'); redisUtils.setString('aaa', '111'); System.out.println(redisUtils.get('aaa')); } } 方式二，依赖注入

与方式一类似，但是需要写死具体使用主的池还是从的池，思路如下：
放弃注解的方式，直接将主和从的两个链接池注入到具体实现类中。

RedisUtils package com.silence.spring.redis.readwriteseparation.util; import com.silence.spring.redis.readwriteseparation.DynamicJedisPoolHolder; import com.silence.spring.redis.readwriteseparation.JedisPoolSelector; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import redis.clients.jedis.JedisPool; /** * Created by keysilence on 16/10/26. */ public class RedisUtils { private static Logger logger = LoggerFactory.getLogger(RedisUtils.class); private JedisPool masterJedisPool; private JedisPool slaveJedisPool; public void setMasterJedisPool(JedisPool masterJedisPool) { this.masterJedisPool = masterJedisPool; } public void setSlaveJedisPool(JedisPool slaveJedisPool) { this.slaveJedisPool = slaveJedisPool; } public String setString(final String key, final String value) { String ret = masterJedisPool.getResource().set(key, value); System.out.println('key:' + key + ',value:' + value + ',ret:' + ret); return ret; } public String get(final String key) { String ret = slaveJedisPool.getResource().get(key); System.out.println('key:' + key + ',ret:' + ret); return ret; } } spring-datasource.xml <?xml version='1.0' encoding='UTF-8'?> <beans xmlns='' xmlns:xsi='' xmlns:aop='' xsi:schemaLocation=' http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop/spring-aop.xsd'> <bean id='poolConfig' class='redis.clients.jedis.JedisPoolConfig'> <!-- 池中最大链接数 --> <property name='maxTotal' value='100'/> <!-- 池中最大空闲链接数 --> <property name='maxIdle' value='50'/> <!-- 池中最小空闲链接数 --> <property name='minIdle' value='20'/> <!-- 当池中链接耗尽，调用者最大阻塞时间，超出此时间将跑出异常。（单位：毫秒；默认为-1，表示永不超时） --> <property name='maxWaitMillis' value='1000'/> <!-- 参考： --> <!-- 调用者获取链接时，是否检测当前链接有效性。无效则从链接池中移除，并尝试继续获取。（默认为false） --> <property name='testOnBorrow' value='true' /> <!-- 向链接池中归还链接时，是否检测链接有效性。（默认为false） --> <property name='testOnReturn' value='true' /> <!-- 调用者获取链接时，是否检测空闲超时。如果超时，则会被移除（默认为false） --> <property name='testWhileIdle' value='true' /> <!-- 空闲链接检测线程一次运行检测多少条链接 --> <property name='numTestsPerEvictionRun' value='10' /> <!-- 空闲链接检测线程检测周期。如果为负值，表示不运行检测线程。（单位：毫秒，默认为-1） --> <property name='timeBetweenEvictionRunsMillis' value='60000' /> <!-- 链接获取方式。队列：false；栈：true --> <!--<property name='lifo' value='false' />--> </bean> <bean id='masterJedisPool' class='redis.clients.jedis.JedisPool'> <constructor-arg index='0' ref='poolConfig'/> <constructor-arg index='1' value='192.168.100.110' type='java.lang.String'/> <constructor-arg index='2' value='6379' type='int'/> </bean> <bean id='slaveJedisPool' class='redis.clients.jedis.JedisPool'> <constructor-arg index='0' ref='poolConfig'/> <constructor-arg index='1' value='192.168.100.110' type='java.lang.String'/> <constructor-arg index='2' value='6380' type='int'/> </bean> <bean id='redisUtils' class='com.silence.spring.redis.readwriteseparation.util.RedisUtils'> <property name='masterJedisPool' ref='masterJedisPool'/> <property name='slaveJedisPool' ref='slaveJedisPool'/> </bean> </beans>