Spring Data Redis实现一个订阅/发布系统
Redis是一个key-value的存储系统,提供的key-value类似与Memcached而数据结构又多于memcached,而且性能优异.广泛用于缓存,临时存储等.而我今天 这个例子是使用Redis实现一个订阅/发布系统,而不是如何使用它存储key-value的数据.
Redis是天生支持订阅/发布的,不是我牵强附会拼凑而实现这样的效果,如果真是这样性能没法保证,而且要实现订阅/发布这样的系统是有很多解决方案的.
下载,安装和配置Redis,见:
- http://www.linuxidc.com/Linux/2012-10/73081.htm
- http://www.linuxidc.com/Linux/2012-10/73082.htm
- http://www.linuxidc.com/Linux/2012-10/73080.htm
- http://www.linuxidc.com/Linux/2012-10/73078.htm
- http://www.linuxidc.com/Linux/2012-10/73079.htm
Spring一直秉承不发明轮子的,对于很多其他技术都是提供一个模板:Template,如JDBC-JdbcTemplate,JMSTemplate等,Redis他也提供RedisTemplate,有了这个RedisTemplate你可以做任何事,存取key-value,订阅,发布等都通过这个对象实现.
实现一个RedisDAO,接口我不贴了
public class RedisDAOImpl implements RedisDAO {
private RedisTemplate<String, Object> redisTemplate = null;
public RedisDAOImpl() {
}
@Override
public void sendMessage(String channel, Serializable message) {
redisTemplate.convertAndSend(channel, message);
}
public RedisTemplate getRedisTemplate() {
return redisTemplate;
}
public void setRedisTemplate(RedisTemplate redisTemplate) {
this.redisTemplate = redisTemplate;
}
}
可以看到,通过这个 sendMessage方法,我可以把一条可序列化的消息发送到channel频道,订阅者只要订阅了这个channel,他就会接收发布者发布的消息.
当然有了发布消息的sendMessage也得有个接收消息的Listener,用于接收订阅到的消息.
代码如:
public class MessageDelegateListenerImpl implements MessageDelegateListener {
@Override
public void handleMessage(Serializable message) {
//什么都不做,只输出
if(message == null){
System.out.println("null");
} else if(message.getClass().isArray()){
System.out.println(Arrays.toString((Object[])message));
} else if(message instanceof List<?>) {
System.out.println(message);
} else if(message instanceof Map<? , ?>) {
System.out.println(message);
} else {
System.out.println(ToStringBuilder.reflectionToString(message));
}
}
}
好了,有上面的两个类,加上Spring基本上就可以工作了.当然还得启动Redis.
Spring Schema:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:redis="http://www.springframework.org/schema/redis"
xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.springframework.org/schema/redis
http://www.springframework.org/schema/redis/spring-redis-1.0.xsd">
<bean id="redisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"
p:hostname="localhost" p:port="6379" p:usePool="true">
</bean>
<!-- redis template definition -->
<bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate"
p:connectionFactory-ref="redisConnectionFactory"/>
<bean id="redisDAO" class="net.dredis.dao.impl.RedisDAOImpl">
<property name="redisTemplate" ref="redisTemplate" />
</bean>
<bean id="listener" class="net.dredis.listener.impl.MessageDelegateListenerImpl"/>
<!-- the default ConnectionFactory -->
<bean id="jdkSerializer" class="org.springframework.data.redis.serializer.JdkSerializationRedisSerializer" />
<redis:listener-container>
<!-- the method attribute can be skipped as the default method name is "handleMessage" -->
<redis:listener ref="listener" serializer="jdkSerializer" method="handleMessage" topic="java" />
</redis:listener-container>
</beans>