许久没发博客，转载一篇Spring Data Redis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://my.oschina.net/u/729474/blog/79128 和http://www.php100.com/html/webkaifa/PHP/PHPyingyong/2011/0406/7873.html

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

01	public class RedisDAOImpl implements RedisDAO {

02

03	private RedisTemplate<String, Object> redisTemplate = null;

04

05	public RedisDAOImpl() {

06

07

}

08

09

@Override

10	public void sendMessage(String channel, Serializable message) {

11	redisTemplate.convertAndSend(channel, message);

12

}

13

14

15	public RedisTemplate getRedisTemplate() {

16	return redisTemplate;

17

}

18

19	public void setRedisTemplate(RedisTemplate redisTemplate) {

20	this.redisTemplate = redisTemplate;

21

}

22

}

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: 

01	public class MessageDelegateListenerImpl implements MessageDelegateListener {

02

03

@Override

04	public void handleMessage(Serializable message) {

05	//什么都不做,只输出

06	if(message == null){

07	System.out.println("null");

08	} else if(message.getClass().isArray()){

09	System.out.println(Arrays.toString((Object[])message));

10	} else if(message instanceof List<?>) {

11	System.out.println(message);

12	} else if(message instanceof Map<? , ?>) {

13	System.out.println(message);

14

} else {

15	System.out.println(ToStringBuilder.reflectionToString(message));

16

}

17

}

18

}

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:

01	<?xml version="1.0" encoding="UTF-8"?>

02	<beans xmlns="http://www.springframework.org/schema/beans"

03	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

04	xmlns:context="http://www.springframework.org/schema/context"

05	xmlns:redis="http://www.springframework.org/schema/redis"

06	xmlns:p="http://www.springframework.org/schema/p"

07

08	xsi:schemaLocation="http://www.springframework.org/schema/beans

09	http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

10	http://www.springframework.org/schema/context

11	http://www.springframework.org/schema/context/spring-context-3.0.xsd

12	http://www.springframework.org/schema/redis

13	http://www.springframework.org/schema/redis/spring-redis-1.0.xsd">

14

15	<bean id="redisConnectionFactory"class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"

16	p:hostName="localhost" p:port="6379" p:usePool="true">

17

</bean>

18

19	<!-- redis template definition -->

20	<bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate"

21	p:connectionFactory-ref="redisConnectionFactory"/>

22

23	<bean id="redisDAO" class="net.dredis.dao.impl.RedisDAOImpl">

24	<property name="redisTemplate" ref="redisTemplate" />

25

</bean>

26

27	<bean id="listener" class="net.dredis.listener.impl.MessageDelegateListenerImpl"/>

28

29	<!-- the default ConnectionFactory -->

30	<bean id="jdkSerializer"class="org.springframework.data.redis.serializer.JdkSerializationRedisSerializer" />

31

32	<redis:listener-container>

33	<!-- the method attribute can be skipped as the default method name is "handleMessage" -->

34	<redis:listener ref="listener" serializer="jdkSerializer" method="handleMessage"topic="java" />

35	</redis:listener-container>

36

</beans>

如上面的配置, jdkSerializer是jdk默认的序列化的实现,当然还有很多其他序列化Java对象的方法,这里使用jdk默认实现. 
Method属性是配置订阅系统接收消息的方法,默认也是"handleMessage" 
topic就是订阅的channel频道,是有发布到java这个channel的消息才会被接收. 

测试类: 

01	public static void main(String[] args) {

02	new ClassPathXmlApplicationContext("pubsubAppContext1.xml");;

03	while (true) { //这里是一个死循环,目的就是让进程不退出,用于接收发布的消息

04

try {

05	System.out.println("current time: " + new Date());

06

07	Thread.sleep(3000);

08	} catch (InterruptedException e) {

09	e.printStackTrace();

10

}

11

}

12

}

OK,启动了订阅系统后,我们就可以发布消息,测试类如: 

01

@Test

02	public void testPublishMessage() throws Exception {

03	String msg = "Hello, Redis!";

04	redisDAO.sendMessage("java", msg); //发布字符串消息

05

06

07	RedisTestBean bean = new RedisTestBean("123456");

08	bean.setName("Redis");

09	bean.setOld((byte)2);

10	bean.setSeliry((short)40);

11	bean.setManbers(new String[]{"234567", "3456789"});

12	redisDAO.sendMessage("java", bean); //发布一个普通的javabean消息

13

14

15	Integer[] values = new Integer[]{21341,123123,12323};

16	redisDAO.sendMessage("java", values);  //发布一个数组消息

17

}

如测试,我连续发布了3条消息,都是不同的数据类型.订阅端输出如:

1	current time: Fri Oct 26 20:38:31 CST 2012

2	[21341, 123123, 12323]

3	java.lang.String@379faa8c[value={H,e,l,l,o,,, ,R,e,d,i,s,!},hash=1345989452]

4	net.dredis.entity.RedisTestBean@7dee05dc[uid=123456,name=Redis,seliry=40,old=2,manbers={234567,3456789}]

5	current time: Fri Oct 26 20:38:34 CST 2012

6	current time: Fri Oct 26 20:38:37 CST 2012

OK他接收到了这3条消息,而且和预期一样. 
对于Spring还有传统风格的配置方式,实现的功能和前面一模一样. 

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01	<?xml version="1.0" encoding="UTF-8"?>

02	<beans xmlns="http://www.springframework.org/schema/beans"

03	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

04	xmlns:context="http://www.springframework.org/schema/context"

05	xmlns:p="http://www.springframework.org/schema/p"

06

07	xsi:schemaLocation="http://www.springframework.org/schema/beans

08	http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

09	http://www.springframework.org/schema/context

10	http://www.springframework.org/schema/context/spring-context-3.0.xsd">

11

12	<bean id="jedisConnectionFactory"class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"

13	p:hostName="localhost" p:port="6379" p:usePool="true">

14

</bean>

15

16	<!-- redis template definition -->

17	<bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate"

18	p:connectionFactory-ref="jedisConnectionFactory"/>

19

20	<bean id="redisDAO" class="net.dredis.dao.impl.RedisDAOImpl">

21	<property name="redisTemplate" ref="redisTemplate" />

22

</bean>

23

24	<bean id="serialization"class="org.springframework.data.redis.serializer.JdkSerializationRedisSerializer" />

25

26	<bean id="messageDelegateListener"class="net.dredis.listener.impl.MessageDelegateListenerImpl" />

27

28	<bean id="messageListener"class="org.springframework.data.redis.listener.adapter.MessageListenerAdapter">

29	<property name="delegate" ref="messageDelegateListener" />

30	<property name="serializer" ref="serialization" />

31

</bean>

32

33	<bean id="redisContainer"class="org.springframework.data.redis.listener.RedisMessageListenerContainer">

34	<property name="connectionFactory" ref="jedisConnectionFactory"/>

35	<property name="messageListeners">

36	<!-- map of listeners and their associated topics (channels or/and patterns) -->

37

<map>

38	<entry key-ref="messageListener">

39	<bean class="org.springframework.data.redis.listener.ChannelTopic">

40	<constructor-arg value="java" />

41

</bean>

42

</entry>

43

</map>

44	</property>

45

</bean>

46

</beans>