Redis（一）------主从实现读写分离
#前言
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.clients
jedis
2.6.2
##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 holder = new ThreadLocal();
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
###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