本篇内容介绍了“Redis监听过期的key实现流程是什么”的有关知识,在实际案例的操作过程中,不少人都会遇到这样的困境,接下来就让小编带领大家学习一下如何处理这些情况吧!希望大家仔细阅读,能够学有所成!
一、简介
我们来个最简单的集群架构,如下图:
我们上面图中看到是服务A和服务B就是同一个服务的不同实例。
二、maven依赖
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.6.0</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.alian</groupId>
<artifactId>expiration</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>expiration</name>
<description>redis-key-expiration-listener</description>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<project.package.directory>target</project.package.directory>
<java.version>1.8</java.version>
<!--com.fasterxml.jackson 版本-->
<jackson.version>2.9.10</jackson.version>
<!--阿里巴巴fastjson 版本-->
<fastjson.version>1.2.68</fastjson.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
</dependency>
<!--redis依赖-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
<version>${parent.version}</version>
</dependency>
<!--用于序列化-->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>${jackson.version}</version>
</dependency>
<!--java 8时间序列化-->
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-jsr310</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.68</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.16.14</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.2</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
三、编码实现
3.1、application.properties
# 端口
server.port=8090
# 上下文路径
server.servlet.context-path=/expiration# Redis数据库索引(默认为0)
spring.redis.database=0
# Redis服务器地址
spring.redis.host=192.168.0.193
#spring.redis.host=127.0.0.1
# Redis服务器连接端口
spring.redis.port=6379
# Redis服务器连接密码(默认为空)
spring.redis.password=
# 连接池最大连接数(使用负值表示没有限制)
spring.redis.jedis.pool.max-active=20
# 连接池中的最小空闲连接
spring.redis.jedis.pool.min-idle=10
# 连接池中的最大空闲连接
spring.redis.jedis.pool.max-idle=10
# 连接池最大阻塞等待时间(使用负值表示没有限制)
spring.redis.jedis.pool.max-wait=20000
# 读时间(毫秒)
spring.redis.timeout=10000
# 连接超时时间(毫秒)
spring.redis.connect-timeout=10000
3.2、Redis配置类
RedisConfig
package com.alian.expiration.config;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.listener.RedisMessageListenerContainer;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
@Configuration
public class RedisConfig {
/**
* redis配置
*
* @param redisConnectionFactory
* @return
*/
@Bean
public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
// 实例化redisTemplate
RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
//设置连接工厂
redisTemplate.setConnectionFactory(redisConnectionFactory);
// key采用String的序列化
redisTemplate.setKeySerializer(keySerializer());
// value采用jackson序列化
redisTemplate.setValueSerializer(valueSerializer());
// Hash key采用String的序列化
redisTemplate.setHashKeySerializer(keySerializer());
// Hash value采用jackson序列化
redisTemplate.setHashValueSerializer(valueSerializer());
// 支持事务
// redisTemplate.setEnableTransactionSupport(true);
//执行函数,初始化RedisTemplate
redisTemplate.afterPropertiesSet();
return redisTemplate;
}
/**
* key类型采用String序列化
*
* @return
*/
private RedisSerializer<String> keySerializer() {
return new StringRedisSerializer();
}
/**
* value采用JSON序列化
*
* @return
*/
private RedisSerializer<Object> valueSerializer() {
//设置jackson序列化
Jackson2JsonRedisSerializer<Object> jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer<>(Object.class);
//设置序列化对象
jackson2JsonRedisSerializer.setObjectMapper(getMapper());
return jackson2JsonRedisSerializer;
}
/**
* 使用com.fasterxml.jackson.databind.ObjectMapper
* 对数据进行处理包括java8里的时间
*
* @return
*/
private ObjectMapper getMapper() {
ObjectMapper mapper = new ObjectMapper();
//设置可见性
mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
//默认键入对象
mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
//设置Java 8 时间序列化
JavaTimeModule timeModule = new JavaTimeModule();
timeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
timeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
timeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
timeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
timeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
timeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
//禁用把时间转为时间戳
mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
mapper.registerModule(timeModule);
return mapper;
}
@Bean
RedisMessageListenerContainer container(RedisConnectionFactory connectionFactory) {
RedisMessageListenerContainer container = new RedisMessageListenerContainer();
container.setConnectionFactory(connectionFactory);
return container;
}
}
和我们之前整合redis差不多,只不过在最后增加了一个redis消息监听监听容器RedisMessageListenerContainer
3.3、监听器
RedisKeyExpirationListener
package com.alian.expiration.listener;
import com.alian.expiration.service.RedisExpirationService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.connection.Message;
import org.springframework.data.redis.listener.KeyExpirationEventMessageListener;
import org.springframework.data.redis.listener.RedisMessageListenerContainer;
import org.springframework.stereotype.Component;
@Slf4j
@Component
public class RedisKeyExpirationListener extends KeyExpirationEventMessageListener {
@Autowired
private RedisExpirationService redisExpirationService;
// 把我们上面一步配置的bean注入进去
public RedisKeyExpirationListener(RedisMessageListenerContainer listenerContainer) {
super(listenerContainer);
}
/**
* 针对redis数据失效事件,进行数据处理
*
* @param message
* @param pattern
*/
@Override
public void onMessage(Message message, byte[] pattern) {
// 用户做自己的业务处理即可,注意message.toString()可以获取失效的key
String expiredKey = message.toString();
log.info("onMessage --> redis 过期的key是:{}", expiredKey);
try {
// 对过期key进行处理
redisExpirationService.processingExpiredKey(expiredKey);
log.info("过期key处理完成:{}", expiredKey);
} catch (Exception e) {
e.printStackTrace();
log.error("处理redis 过期的key异常:{}", expiredKey, e);
}
}
}
实现的步骤如下:
继承KeyExpirationEventMessageListener
把redis消息监听监听容器RedisMessageListenerContainer 注入到密钥空间事件消息侦 听器中
重写onMessage方法
通过Message 的 toString() 方法就可以获取到过期的key
对key中关键信息进行业务处理,比如 id
3.4、服务类
RedisExpirationService
package com.alian.expiration.service;
import com.alian.expiration.util.SignUtils;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;
import java.util.concurrent.TimeUnit;
@Slf4j
@Service
public class RedisExpirationService {
@Autowired
private RedisTemplate<String, Object> redisTemplate;
public void processingExpiredKey(String expiredKey) {
// 如果是优惠券的key(一定要规范命名)
if (expiredKey.startsWith("com.mall.coupon.id")) {
// 临时key,此key可以在业务处理完,然后延迟一定时间删除,或者不处理
String tempKey = SignUtils.md5(expiredKey, "UTF-8");
// 临时key不存在才设置值,key超时时间为10秒(此处相当于分布式锁的应用)
Boolean exist = redisTemplate.opsForValue().setIfAbsent(tempKey, "1", 10, TimeUnit.SECONDS);
if (Boolean.TRUE.equals(exist)) {
log.info("Business Handing...");
// 比如截取里面的id,然后关联数据库进行处理
} else {
log.info("Other service is handing...");
}
} else {
log.info("Expired keys without processing");
}
}
}
基本流程如下:
判断是否是需要处理的key,一般这种key通过命名规范加以处理
以当前key生成一个新的key作为分布式key
如果redis中不存在这个新的key,则为新的key设置一个值,达到分布式服务处理(核心)
设置成功的,进行业务处理;设置失败了,说明其他服务正在处理这个key
根据 key 的关键信息(比如截取id),进行业务处理
3.5、工具类
SignUtils
package com.alian.expiration.util;
import java.security.MessageDigest;
public class SignUtils {
public static final String md5(String s, String charset) {
char[] hexDigits = new char[]{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
try {
byte[] btInput = s.getBytes(charset);
MessageDigest mdInst = MessageDigest.getInstance("MD5");
mdInst.update(btInput);
byte[] md = mdInst.digest();
int j = md.length;
char[] str = new char[j * 2];
int k = 0;
for (byte byte0 : md) {
str[k++] = hexDigits[byte0 >>> 4 & 15];
str[k++] = hexDigits[byte0 & 15];
}
return new String(str);
} catch (Exception var11) {
return "";
}
}
}
四、测试
4.1、测试类
简单模拟下发送一个优惠券数据到redis,然后设置超时时间
package com.alian.expiration;
import lombok.extern.slf4j.Slf4j;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
@Slf4j
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
public class RedisKeyExpirationTest {
@Autowired
private RedisTemplate<String, Object> redisTemplate;
@Test
public void keyExpiration() {
// 优惠券信息
String id = "2023021685264735";
Map<String, String> map = new HashMap<>();
map.put("id", id);
map.put("amount", "1000");
map.put("type", "1001");
map.put("describe", "满减红包");
// 缓存到redis
redisTemplate.opsForHash().putAll("com.mall.coupon.id." + id, map);
// 设置过期时间
redisTemplate.expire("com.mall.coupon.id." + id, 10, TimeUnit.SECONDS);
}
}
4.2、单实例
单实例就是服务只部署了一份,我们启动一份,端口是8090,然后通过上面的测试类,发送一个消息,结果如下:
10:23:39 701 INFO [container-2]:onMessage --> redis 过期的key是:com.mall.coupon.id.2023021685264735
10:23:39 988 INFO [container-2]:Business Handing...
10:23:39 989 INFO [container-2]:过期key处理完成:com.mall.coupon.id.2023021685264735
10:23:50 005 INFO [container-3]:onMessage --> redis 过期的key是:450FCC35415BADC16805962CA5BC7E12
10:23:50 005 INFO [container-3]:Expired keys without processing
10:23:50 005 INFO [container-3]:过期key处理完成:450FCC35415BADC16805962CA5BC7E12
4.3、多实例
多实例就是服务部署了多份,比如我们启动两份,端口分别为8090和8091,然后通过上面的测试类,发送一个消息,8090端口的服务结果如下(Business Handing…):
11:39:06 691 INFO [container-2]:onMessage --> redis 过期的key是:com.mall.coupon.id.2023021685264735
11:39:06 707 INFO [container-2]:Business Handing...
11:39:06 707 INFO [container-2]:过期key处理完成:com.mall.coupon.id.2023021685264735
11:39:16 796 INFO [container-3]:onMessage --> redis 过期的key是:450FCC35415BADC16805962CA5BC7E12
11:39:16 796 INFO [container-3]:Expired keys without processing
11:39:16 796 INFO [container-3]:过期key处理完成:450FCC35415BADC16805962CA5BC7E12
8091端口的服务结果如下(Other service is handing…):
11:39:06 691 INFO [container-2]:onMessage --> redis 过期的key是:com.mall.coupon.id.2023021685264735
11:39:06 707 INFO [container-2]:Other service is handing...
11:39:06 707 INFO [container-2]:过期key处理完成:com.mall.coupon.id.2023021685264735
11:39:16 796 INFO [container-3]:onMessage --> redis 过期的key是:450FCC35415BADC16805962CA5BC7E12
11:39:16 796 INFO [container-3]:Expired keys without processing
11:39:16 796 INFO [container-3]:过期key处理完成:450FCC35415BADC16805962CA5BC7E12
结果分析:
多实例的情况下,每个实例都会收到过期key通知
通过redis分布式锁,实现只有一个实例会进行业务处理,防止重复
使用分布式锁会有一个新的key过期,并且收到该key的通知,你可以业务执行完延迟一定时间(避免重复执行),再删除,也可以不处理(因为本就不是要处理业务的key)