Redis---監聽Key過期事件

在實際的開發項目中，監聽 key 的過期事件，應用非常廣泛，例如：優惠券過期，處理各種超時事件等等

先貼出SpringBoot工程結構

實現步驟： 

1.修改Redis配置文件

   找到 redis.windows.conf或redis.conf 文件，搜索 “notify-keyspace-events”找到原本的notify-keyspace-events " "，修改為 “notify-keyspace-events Ex”，這樣我們的 Redis 就支持 key 過期事件的監聽了

  

 2.添加依賴

<!-- redis -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

3.配置yml

spring:
  application:
    name: Redis
  redis:
    host: 127.0.0.1
    port: 6379

4.創建監聽類

package com.zk.redis.redisTimeoutEvent;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.connection.Message;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.listener.KeyExpirationEventMessageListener;
import org.springframework.data.redis.listener.RedisMessageListenerContainer;
import org.springframework.stereotype.Component;
import java.nio.charset.StandardCharsets;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.TimeUnit;

@Slf4j
@Component
public class KeyExpiredListener extends KeyExpirationEventMessageListener {

    @Autowired
    public RedisTemplate<String,String> redisTemplate;

    public KeyExpiredListener(RedisMessageListenerContainer listenerContainer) {
        super(listenerContainer);
    }

    @Override
    public void onMessage(Message message, byte[] bytes) {
        //獲取失效key名稱
        String expireKey = new String(message.getBody(), StandardCharsets.UTF_8);
        //獲取key原本的value 獲取不到 是null
        String expireKeyValue = redisTemplate.opsForValue().get("myKey");
        log.info("expireKey---"+expireKey);
        log.info("expireKeyValue---"+expireKeyValue);
    }
}

5.創建一個配置類RedisListenerConfig

package com.zk.redis.redisTimeoutEvent;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.listener.RedisMessageListenerContainer;

@Configuration
public class RedisListenerConfig {
    @Bean
    RedisMessageListenerContainer container(RedisConnectionFactory connectionFactory) {
        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
        container.setConnectionFactory(connectionFactory);
        return container;
    }
}

6.寫一個Controller測試一下

package com.zk.redis.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

@RestController
public class RedisController {

    @Autowired
    public RedisTemplate<String,String> redisTemplate;

    @RequestMapping(value = "/redisTest", method = RequestMethod.GET, produces = "application/json;charset=UTF-8")
    public Map<String,Object> redisTest(){
         //redis中存入5秒失效的key
        redisTemplate.opsForValue().set("myKey", "myValue",5, TimeUnit.SECONDS);
        String myKey = redisTemplate.opsForValue().get("myKey");
        Map<String,Object> resultMap = new HashMap<String,Object>();
        resultMap.put("myKey",myKey);
        return resultMap;
    }
}

7.項目運行后，瀏覽器輸入訪問地址，輸出結果，說明key失效后觸發onMessage().

上圖說明成功監聽並觸發事件.