许久没发博客，转载一篇Spring Data Redis订阅/发布系统 -

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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

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public class RedisDAOImpl implements RedisDAO {

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    private RedisTemplate<String, Object> redisTemplate = null;

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    public RedisDAOImpl() {

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    }

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    @Override

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    public void sendMessage(String channel, Serializable message) {

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        redisTemplate.convertAndSend(channel, message);

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    }

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    public RedisTemplate getRedisTemplate() {

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        return redisTemplate;

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    }

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    public void setRedisTemplate(RedisTemplate redisTemplate) {

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        this.redisTemplate = redisTemplate;

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    }

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}

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:

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public class MessageDelegateListenerImpl implements MessageDelegateListener {

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    @Override

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    public void handleMessage(Serializable message) {

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        //什么都不做,只输出

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        if(message == null){

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            System.out.println("null");

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

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

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

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            System.out.println(message);

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

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            System.out.println(message);

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        } else {

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

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        }

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    }

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}

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:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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    </bean>

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    <!-- redis template definition -->

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

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          p:connectionFactory-ref="redisConnectionFactory"/>

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

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

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    </bean>

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

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    <!-- the default ConnectionFactory -->

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

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    <redis:listener-container>

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

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

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    </redis:listener-container>

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</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:

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public static void main(String[] args) {

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        new ClassPathXmlApplicationContext("pubsubAppContext1.xml");;

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        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

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            try {

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

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                Thread.sleep(3000);

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            } catch (InterruptedException e) {

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                e.printStackTrace();

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            }

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        }

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    }

OK,启动了订阅系统后,我们就可以发布消息,测试类如:

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@Test

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    public void testPublishMessage() throws Exception {

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        String msg = "Hello, Redis!";

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

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        RedisTestBean bean = new RedisTestBean("123456");

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        bean.setName("Redis");

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        bean.setOld((byte)2);

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        bean.setSeliry((short)40);

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

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

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

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

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    }

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:

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

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[21341, 123123, 12323]

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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    </bean>

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    <!-- redis template definition -->

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

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          p:connectionFactory-ref="jedisConnectionFactory"/>

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

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

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    </bean>

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

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

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

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

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

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    </bean>

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

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

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        <property name="messageListeners">

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

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            <map>

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                <entry key-ref="messageListener">

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

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                        <constructor-arg value="java" />

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                    </bean>

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                </entry>

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            </map>

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        </property>

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    </bean>

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</beans>