NoSQL之Redis---PUB/SUB(订阅与发布)---JAVA实现

[不忘初心]

前文我们介绍了使用Redis基本命令的方式来实现发布与订阅的功能，但是在实际开发中，我们更多会使用高级语言使用Redis。本文我们就来演示如何使用java语言来实现订阅与发布功能。先特别声明：本文所示代码参考自其他博文，详情见篇尾。

准备工作：

a.操作系统：windows 7

b.其他软件：redis 3.2 ， jdk 1.7，eclipse mars

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一。非持久化的订阅与发布

1.新建Maven工程，工程类型为quickstart。并修改buildpath中的jre版本为1.7.

2.修改pom文件内容，具体如下：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.csdn.ingo</groupId><artifactId>redis-pub-sub</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>redis-pub-sub</name><url>http://maven.apache.org</url><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>3.8.1</version><scope>test</scope></dependency><dependency><groupId>redis.clients</groupId><artifactId>jedis</artifactId><version>2.8.0</version></dependency><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.17</version></dependency></dependencies></project>

3.读者按需增加日志配置文件，下文我们使用系统输出代替日志。

log4j.rootLogger=info,stdout  log4j.appender.stdout=org.apache.log4j.ConsoleAppender  log4j.appender.stdout.layout=org.apache.log4j.PatternLayout  log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n  

4.创建Publisher.java文件，作为消息的发布者，具体内容如下：

package com.csdn.ingo.redis_pub_sub;import java.io.BufferedReader;import java.io.InputStreamReader;import redis.clients.jedis.Jedis;/***@author 作者 E-mail：ingo*@version 创建时间：2016年6月14日上午9:49:41*类说明*/public class Publisher {private Jedis publisherJedis;private String channel;public Publisher(Jedis publishJedis,String channel){this.publisherJedis=publishJedis;this.channel=channel;}public void startPublish(){try{BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));while(true){System.out.println("请输入message:");String line = reader.readLine();if(!"quit".equals(line)){publisherJedis.publish(channel, line);}else{break;}}}catch(Exception e){e.printStackTrace();}}}

5.创建Subscriber.java文件，作为消息的接收者，具体内容如下：

package com.csdn.ingo.redis_pub_sub;import redis.clients.jedis.JedisPubSub;public class Subscriber extends JedisPubSub {@Overridepublic void onMessage(String channel, String message) {System.out.println("Channel:" + channel + ",Message:" + message);}@Overridepublic void onPMessage(String pattern, String channel, String message) {System.out.println("Pattern:" + pattern + ",Channel:" + channel + ",Message:" + message);}@Overridepublic void onSubscribe(String channel, int subscribedChannels) {System.out.println("onSubscribe---channel:"+channel+",subscribedChannels:"+subscribedChannels);}@Overridepublic void onPUnsubscribe(String pattern, int subscribedChannels) {System.out.println("onPUnsubscribe---pattern:"+pattern+",subscribedChannels:"+subscribedChannels);}@Overridepublic void onPSubscribe(String pattern, int subscribedChannels) {System.out.println("onPSubscribe---pattern:"+pattern+",subscribedChannels:"+subscribedChannels);}}

6.创建测试Main.java，具体内容如下：

package com.csdn.ingo.redis_pub_sub;import redis.clients.jedis.Jedis;import redis.clients.jedis.JedisPool;import redis.clients.jedis.JedisPoolConfig;/** * @author 作者 E-mail：ingo * @version 创建时间：2016年6月14日上午9:55:01 类说明 */public class TestMain {public static final String CHANNEL = "mychannel";public static final String HOST = "127.0.0.1";public static final int PORT = 6379;private final static JedisPoolConfig POOL_CONFIG = new JedisPoolConfig();private final static JedisPool JEDIS_POOL = new JedisPool(POOL_CONFIG, HOST, PORT, 0);public static void main(String[] args) {final Jedis subscriberJedis = JEDIS_POOL.getResource();final Jedis publisherJedis = JEDIS_POOL.getResource();final Subscriber subscriber = new Subscriber();new Thread(new Runnable() {public void run() {try {System.out.println("Subscribing to mychannel,this thread will be block");subscriberJedis.subscribe(subscriber, CHANNEL);System.out.println("subscription ended");} catch (Exception e) {e.printStackTrace();}}}).start();new Publisher(publisherJedis, CHANNEL).startPublish();publisherJedis.close();subscriber.unsubscribe();subscriberJedis.close();}}

7.测试方法：首先，启动main方法中所示地址的Redis服务器；然后，运行main方法，观察控制台输出。并且我们是以控制台输入内容作为消息发布的内容，各位看官可以在控制台输入任意内容，点击回车键，观察控制台输出。示例如下：

注意：此方法实现的发布与订阅功能，消息不会在Redis客户端进行缓存。

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二。持久化的订阅与发布。【其本质就是在发布消息之前，将消息先存入到Redis中，在调用发布命令】

1.在上文使用的工程中新建持久化方式的package，或者新建与上文同样的工程。

2.新建PPubClient.java，作为持久化的发布者，具体内容如下：

package com.csdn.ingo.redis.persistence;import java.util.Set;import redis.clients.jedis.Jedis;/***@author 作者 E-mail：ingo*@version 创建时间：2016年6月16日上午8:55:21*类说明*/public class PPubClient {private Jedis jedis;private String CONSTANT_CLIENTSET = "clientSet";public PPubClient(String host,int port){jedis = new Jedis(host,port);}private void put(String message){Set<String> subClients = jedis.smembers(CONSTANT);for(String clientKey:subClients){jedis.rpush(clientKey, message);}}public void pub(String channel,String message){Long txid = jedis.incr("MAXID");String content = txid+"/"+message;this.put(content);jedis.publish(channel, message);}public void close(String channel){jedis.publish(channel, "quit");jedis.del(channel);}}

2.新建PPSubClient.java，作为持久化的接收者，具体内容如下：

package com.csdn.ingo.redis.persistence;import redis.clients.jedis.Jedis;import redis.clients.jedis.JedisPubSub;/***@author 作者 E-mail：ingo*@version 创建时间：2016年6月16日上午9:01:45*类说明*/public class PPSubClient {private Jedis jedis;private JedisPubSub listener;private String CONSTANT_CLIENTSET="clientSet";public PPSubClient(String host,int port,String clientId){jedis = new Jedis(host,port);listener = new PPrintListener(clientId,new Jedis(host,port));jedis.sadd(<span style="font-family: 'Microsoft YaHei';">CONSTANT_CLIENTSET</span><span style="font-family: 'Microsoft YaHei';">, clientId);</span>}public void sub(String channel){jedis.subscribe(listener, channel);}public void unsubscribe(String channel){listener.unsubscribe(channel);}}

3.新建PPrintListener.java，作为持久化消息接收者的输出。具体内容如下：

package com.csdn.ingo.redis.persistence;import java.util.Date;import redis.clients.jedis.Jedis;import redis.clients.jedis.JedisPubSub;/** * @author 作者 E-mail：ingo * @version 创建时间：2016年6月16日上午8:30:00 类说明 */public class PPrintListener extends JedisPubSub {private String clientId;private PSubHandler handler;private String CONSTANT = "clientSet";public PPrintListener(String clientId, Jedis jedis) {this.clientId = clientId;handler = new PSubHandler(jedis);}@Overridepublic void onMessage(String channel, String message) {if (message.equalsIgnoreCase("quit")) {this.unsubscribe(channel);}handler.handle(channel, message);System.out.println("message receive:" + message + ",channel:" + channel);}private void message(String channel, String message) {Date time = new Date();System.out.println("message receive:" + message + ",channel:" + channel + time.toString());}@Overridepublic void onPMessage(String pattern, String channel, String message) {System.out.println("message receive:" + message + ",pattern channel:" + channel);}@Overridepublic void onSubscribe(String channel, int subscribedChannels) {handler.subscribe(channel);System.out.println("subscribe:" + channel + ",total channels:" + subscribedChannels);}@Overridepublic void onUnsubscribe(String channel, int subscribedChannels) {handler.unsubscribe(channel);System.out.println("unsubscribe:" + channel + ",total channels:" + subscribedChannels);}@Overridepublic void onPSubscribe(String pattern, int subscribedChannels) {System.out.println("subscribe pattern:" + pattern + ",total channels:" + subscribedChannels);}@Overridepublic void unsubscribe(String... channels) {super.unsubscribe(channels);for (String channel : channels) {handler.unsubscribe(channel);}}class PSubHandler {private Jedis jedis;PSubHandler(Jedis jedis) {this.jedis = jedis;}public void handle(String channel, String message) {int index = message.indexOf("/");if (index < 0) {return;}Long txid = Long.valueOf(message.substring(0, index));String key = clientId + "/" + channel;while (true) {String lm = jedis.lindex(key, 0);if (lm == null) {break;}int li = lm.indexOf("/");if(li<0){String result = jedis.lpop(key);if(result == null){break;}message(channel, lm);continue;}Long lxid = Long.valueOf(lm.substring(0, li));if(txid>=lxid){jedis.lpop(key);message(channel,lm);continue;}else{break;}}}public void subscribe(String channel){String key = clientId+"/"+channel;boolean exist = jedis.sismember(CONSTANT, key);if(!exist){jedis.sadd(CONSTANT, key);}}public void unsubscribe(String channel){String key = clientId+"/"+channel;jedis.srem(CONSTANT, key);jedis.del(key);}}}

4.创建测试Main方法，具体内容如下：

package com.csdn.ingo.redis.persistence;/** * @author 作者 E-mail：ingo * @version 创建时间：2016年6月16日上午9:07:00 类说明 */public class PPubSubTestMain {public static void main(String[] args) throws Exception {String host = "127.0.0.1";int port = 6379;String clientId = "myclient";PPubClient pubClient = new PPubClient(host, port);final String channel = "mychannel";final PPSubClient subClient = new PPSubClient(host, port, clientId);Thread subThread = new Thread(new Runnable() {public void run() {System.out.println("------------sub----start------------");subClient.sub(channel);System.out.println("------------sub----end------------");}});subThread.setDaemon(true);subThread.start();int i = 0;while (i < 20) {String message = "message--" + i;pubClient.pub(channel, message);i++;Thread.sleep(100);}subClient.unsubscribe(channel);}}

5.测试方法：首先，启动main方法中所示地址的Redis服务器；然后，运行main方法，观察控制台输出。这次我们是以循环调用作为输入内容作为消息发布的内容，各位看官观察控制台输出。示例如下：

然后，打开Redis客户端，观察当前Redis中保留的所有数据：

题外的话：

Redis目前提供的发布与订阅功能，将会完全阻塞订阅者的客户端，在java实现时，即需要保留一个线程来专门处理发布者与订阅者的连接。因此，在实际应用时，更加推荐的做法是使用MQ组件来实现该功能。

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至此，NoSQL之Redis---PUB/SUB(订阅与发布)---JAVA实现 结束

在此，对以下参考资料的作者表示感谢！：

参考资料：

redis官网：

http://redis.io/topics/pubsub

其他博文：

http://my.oschina.net/itblog/blog/601284?fromerr=FiejlElw

http://www.sxrczx.com/pages/shift-alt-ctrl.iteye.com/blog/1867454.html