I was using Spring Boot and wanted to implement a cache, so I tried it.
Several caches are available in Spring Boot. https://docs.spring.io/spring-boot/docs/2.1.6.RELEASE/reference/html/boot-features-caching.html
Looking from above, EhCache 2.x seems to be easy to install. It is said that if there is ehcache.xml in the classpath, it will be used, so it seems easy to introduce, so I will try it.
EhCache 2.x
This time, let's call it from the class annotated with @ SpringBootApplication.
Annotate @EnableCaching
CacheApplication.java
@SpringBootApplication
@EnableCaching
public class CacheApplication implements CommandLineRunner {
@Autowired
Cache cache;
private final static Logger logger = LoggerFactory.getLogger(CacheApplication.class);
private final static DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("HH:mm:ss");
public static void main(String[] args) {
SpringApplication.run(CacheApplication.class, args);
}
public void run(String[] args){
this.getValue("Be cached");
this.getValue("Be cached");//Be cached
this.getValue("Not cached because the arguments are different");//Not cached because the arguments are different
this.getValue("Be cached");//引数違うのを挟んでBe cached
try {
Thread.sleep(3000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
this.getValue("Be cached");//The arguments are the same, but they are not cached because they have passed the lifetime.
}
public void getValue(String key){
logger.info(key + " Start at: " + LocalDateTime.now().format(dateTimeFormatter));
String ret = cache.getFromCache(key); //Cache-enabled methods
logger.info(ret + " End at: " + LocalDateTime.now().format(dateTimeFormatter));
}
}
Add @Cacheable to the method you want to enable caching
Cache.java
@Component
public class Cache {
@Cacheable("getCache") //Enable caching for this method
public String getFromCache(String key){
try {
Thread.sleep(3000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
return "End getFromCache:" + key;
}
}
pom.xml
Add two systems, spring-boot-starter-cache and ʻehcache`, to pom.xml.
pom.xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-cache</artifactId>
</dependency>
<dependency>
<groupId>net.sf.ehcache</groupId>
<artifactId>ehcache</artifactId>
<version>2.10.3</version>
</dependency>
ehcache.xml
Create ehcache.xml under src / main / resources /.
Set timeToLiveSeconds to 5 and set the cache lifetime to 5 seconds.
ehcache.xml
<?xml version="1.0" encoding="UTF-8"?>
<ehcache>
<diskStore path="java.io.tmpdir"/>
<cache
name="getCache"
timeToLiveSeconds="5"
maxEntriesLocalHeap="0">
</cache>
</ehcache>
application.properties Add the following settings to application.properties to use ehcache. This is not necessary if the only cache available is ehcache.
spring.cache.type=ehcache
I will do it. The execution result is like this.
2020-02-29 21:29:48 -Cached Start at: 21:29:48
2020-02-29 21:29:51 - End getFromCache:Cached End at: 21:29:51
2020-02-29 21:29:51 -Cached Start at: 21:29:51
2020-02-29 21:29:51 - End getFromCache:Cached End at: 21:29:51
2020-02-29 21:29:51 -Not cached because the arguments are different Start at: 21:29:51
2020-02-29 21:29:54 - End getFromCache:Not cached because the arguments are different End at: 21:29:54
2020-02-29 21:29:54 -Cached Start at: 21:29:54
2020-02-29 21:29:54 - End getFromCache:Cached End at: 21:29:54
2020-02-29 21:29:57 -Cached Start at: 21:29:57
2020-02-29 21:30:00 - End getFromCache:Cached End at: 21:30:00
We will see the results below. The first time it takes 3 seconds, but the second time is a moment, so the cache seems to be working.
2020-02-29 21:29:48 -Cached Start at: 21:29:48
2020-02-29 21:29:51 - End getFromCache:Cached End at: 21:29:51
2020-02-29 21:29:51 -Cached Start at: 21:29:51
2020-02-29 21:29:51 - End getFromCache:Cached End at: 21:29:51
If you pass a different argument, it will not be cached, so it will take another 3 seconds.
2020-02-29 21:29:51 -Not cached because the arguments are different Start at: 21:29:51
2020-02-29 21:29:54 - End getFromCache:Not cached because the arguments are different End at: 21:29:54
The following is over 5 seconds of survival time, so it is not cached and takes 3 seconds.
2020-02-29 21:29:57 -Cached Start at: 21:29:57
2020-02-29 21:30:00 - End getFromCache:Cached End at: 21:30:00
The cache behaves as intended.
I thought that SpringBoot and EhCache2.X are quick because the cache can be implemented only with annotations and configuration files. However, after learning that the EhCache3 series is already available, you may not dare to use the EhCache2 series.
When I tried caffeine, I was able to implement the cache in the same way, so it seems that I can use that as well. The following article was helpful. https://qiita.com/yut_arrows/items/4b664acdfa852c0bd6cd
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