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redis发布订阅Java代码实现

冰湖一角 2019-01-23 16:51:00 阅读数:169 评论数:0 点赞数:0 收藏数:0

Redis除了可以用作缓存数据外,另一个重要用途是它实现了发布订阅(pub/sub)消息通信模式:发送者(pub)发送消息,订阅者(sub)接收消息。

为了实现redis的发布订阅机制,首先要打开redis服务;其次,引入redis需要的jar包,在pom.xml配置文件加入以下代码:

<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.1.0</version>
</dependency>

由于订阅消息通道需要再tomcat启动时触发,因此,需要创建一个listener监听器,在监听器里实现redis订阅,在web.xml里配置监听器如下:

<listener>
<listener-class>com.test.listener.InitListener</listener-class>
</listener>

一、订阅消息(InitListener实现)

redis支持多通道订阅,一个客户端可以同时订阅多个消息通道,如下代码所示,订阅了13个通道。由于订阅机制是线程阻塞的,需要额外开启一个线程专门用于处理订阅消息及接收消息处理。

public class InitListener implements ServletContextListener{
private Logger logger = Logger.getLogger(InitListener.class);
@Override
public void contextInitialized(ServletContextEvent sce) {
logger.info("启动tomcat");// 连接redis
Map<String, String> proMap = PropertyReader.getProperties();
final String url = proMap.get("redis.host");
final Integer port = Integer.parseInt(proMap.get("redis.port"));
final ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("classpath*:applicationContext.xml");
final RedisSubListener redisSubListener = (RedisSubListener) classPathXmlApplicationContext.getBean("redisSubListener");
// 为防止阻塞tomcat启动,开启线程执行
new Thread(new Runnable(){
public void run(){
// 连接redis,建立监听
Jedis jedis = null;
while(true){
//解码资源更新通知,画面选看回复,画面选看停止回复,预案启动,预案停止,轮切启动,轮切停止,预案启动回复,预案停止回复,轮切启动回复,轮切停止回复,监视屏分屏状态通知,画面状态通知
String[] channels = new String[] { "decodeResourceUpdateNtf", "tvSplitPlayRsp","tvSplitPlayStopRsp",
"planStartStatusNtf", "planStopStatusNtf", "pollStartStatusNtf", "pollStopStatusNtf",
"planStartRsp","planStopRsp","pollStartRsp","pollStopRsp","tvSplitTypeNtf","tvSplitStatusNtf"};
try{
jedis = new Jedis(url,port);
logger.info("redis请求订阅通道");
jedis.subscribe(redisSubListener,channels);
logger.info("redis订阅结束");
}catch(JedisConnectionException e){
logger.error("Jedis连接异常,异常信息 :" + e);
}catch(IllegalStateException e){
logger.error("Jedis异常,异常信息 :" + e);
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
if(jedis != null){
jedis = null;
}
}
}})
.start();
}

最后在spring配置文件里接入以下配置:

<!-- redis -->
<bean id="redisMessageService" class="com.test.service.impl.RedisMessageServiceImpl" scope="singleton">
<property name="webSocketService"><ref local="webSocketService" /></property>
<property name="tvSplitStatusDao" ref="tvSplitStatusDao"></property>
</bean>
<bean id="redisSubListener" class="com.test.common.RedisSubListener" scope="singleton">
<property name="redisMessageService"><ref local="redisMessageService" /></property>
</bean>
RedisMessageServiceImpl用于处理接收的redis消息。

二、发布消息

public class RedisPublishUtil {
private Logger logger = Logger.getLogger(RedisPublishUtil.class);
public static Jedis pubJedis;
private static Map<String, String> proMap = PropertyReader.getProperties();
private static final String redisPort = proMap.get("redis.port");
private static String url = proMap.get("redis.host");
private static final int port = Integer.parseInt(redisPort);
public void setPubJedis(Jedis jedis) {
RedisPublishUtil.pubJedis = jedis;
}

public Jedis getPubJedis() {
if (pubJedis == null) {
createJedisConnect();
}
// 返回对象
return pubJedis;
}
public Jedis createJedisConnect(){
// 连接redis
logger.info("===创建连接jedis=====");
try {
pubJedis = new Jedis(url, port);
} catch (JedisConnectionException e) {
logger.error("Jedis连接异常,异常信息 :" + e.getMessage());
try {
Thread.sleep(1000);
logger.info("发起重新连接jedis");
createJedisConnect();
} catch (InterruptedException except) {
except.printStackTrace();
}
}
// 返回对象
return pubJedis;
}
//公共发布接口
public void pubRedisMsg(String msgType,String msg){
logger.info("redis准备发布消息内容:" + msg);
try {
this.getPubJedis().publish(msgType, msg);
} catch (JedisConnectionException e) {
logger.error("redis发布消息失败!", e);
this.setPubJedis(null);
logger.info("重新发布消息,channel="+msgType);
pubRedisMsg(msgType, msg);
}
}
}
public class PropertyReader {
private static Logger logger = Logger.getLogger(PropertyReader.class);
/*
* 获得数据库链接的配置文件
*/
public static Map<String,String> getProperties(){
logger.info("读取redis配置文件开始。。。");
Properties prop = new Properties();
Map<String,String> proMap = new HashMap<String,String>();
try {
//读取属性文件redis.properties
InputStream in= PropertyReader.class.getClassLoader().getResourceAsStream("redis.properties");
prop.load(in); ///加载属性列表
Iterator<String> it=prop.stringPropertyNames().iterator();
while(it.hasNext()){
String key=it.next();
proMap.put(key, prop.getProperty(key));
}
in.close();
logger.info("读取redis配置文件成功。。。");
} catch (Exception e) {
logger.error("读取redis配置文件异常!", e);
e.printStackTrace();
}
return proMap;
}
}

 

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本文为[冰湖一角]所创,转载请带上原文链接,感谢
https://www.cnblogs.com/bingyimeiling/p/10309970.html

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