spring-boot ehcache example added (#6012)

spring-ehcache/src/main/java/com/baeldung/cachetest/Application.java

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+package com.baeldung.cachetest;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+
+	public static void main(String[] args) {
+		SpringApplication.run(Application.class, args);
+	}
+
+}

spring-ehcache/src/main/java/com/baeldung/cachetest/config/CacheConfig.java

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+package com.baeldung.cachetest.config;
+
+import java.math.BigDecimal;
+import java.time.Duration;
+
+import javax.cache.CacheManager;
+
+import org.ehcache.config.CacheConfiguration;
+import org.ehcache.config.ResourcePools;
+import org.ehcache.config.builders.CacheConfigurationBuilder;
+import org.ehcache.config.builders.CacheEventListenerConfigurationBuilder;
+import org.ehcache.config.builders.ExpiryPolicyBuilder;
+import org.ehcache.config.builders.ResourcePoolsBuilder;
+import org.ehcache.config.units.EntryUnit;
+import org.ehcache.config.units.MemoryUnit;
+import org.ehcache.event.EventType;
+import org.ehcache.jsr107.Eh107Configuration;
+import org.springframework.boot.autoconfigure.cache.JCacheManagerCustomizer;
+import org.springframework.cache.annotation.EnableCaching;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@EnableCaching
+public class CacheConfig {
+
+	private static final int ON_HEAP_CACHE_SIZE_ENTRIES = 2;
+	private static final int OFF_HEAP_CACHE_SIZE_MB = 10;
+	private static final int CACHE_EXPIRY_SECONDS = 30;
+
+	@Bean
+	public JCacheManagerCustomizer jcacheManagerCustomizer() {
+		return new JCacheManagerCustomizer() {
+
+			@Override
+			public void customize(CacheManager cacheManager) {
+				ResourcePools resourcePools = ResourcePoolsBuilder.newResourcePoolsBuilder()
+						.heap(ON_HEAP_CACHE_SIZE_ENTRIES, EntryUnit.ENTRIES)
+						.offheap(OFF_HEAP_CACHE_SIZE_MB, MemoryUnit.MB).build();
+
+				CacheEventListenerConfigurationBuilder eventLoggerConfig = CacheEventListenerConfigurationBuilder
+						.newEventListenerConfiguration(new CacheEventLogger(), EventType.CREATED, EventType.EXPIRED)
+						.unordered().asynchronous();
+
+				CacheConfiguration<?, ?> cacheConfiguration = CacheConfigurationBuilder
+						.newCacheConfigurationBuilder(Long.class, BigDecimal.class, resourcePools)
+						.withExpiry(ExpiryPolicyBuilder.timeToLiveExpiration(Duration.ofSeconds(CACHE_EXPIRY_SECONDS)))
+						.add(eventLoggerConfig).build();
+
+				cacheManager.createCache("squareCache",
+						Eh107Configuration.fromEhcacheCacheConfiguration(cacheConfiguration));
+
+			}
+		};
+	}
+
+}

spring-ehcache/src/main/java/com/baeldung/cachetest/config/CacheEventLogger.java

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+package com.baeldung.cachetest.config;
+
+import org.ehcache.event.CacheEvent;
+import org.ehcache.event.CacheEventListener;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class CacheEventLogger implements CacheEventListener<Object, Object> {
+
+	private static final Logger log = LoggerFactory.getLogger(CacheEventLogger.class);
+
+	@Override
+	public void onEvent(CacheEvent<? extends Object, ? extends Object> cacheEvent) {
+		log.info("Cache event {} for item with key {}. Old value = {}, New value = {}", cacheEvent.getType(),
+				cacheEvent.getKey(), cacheEvent.getOldValue(), cacheEvent.getNewValue());
+	}
+
+}

spring-ehcache/src/main/java/com/baeldung/cachetest/rest/NumberController.java

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+package com.baeldung.cachetest.rest;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.MediaType;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.baeldung.cachetest.service.NumberService;
+
+@RestController
+@RequestMapping(path = "/number", produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
+public class NumberController {
+
+	private final static Logger log = LoggerFactory.getLogger(NumberController.class);
+
+	@Autowired
+	private NumberService numberService;
+
+	@GetMapping(path = "/square/{number}")
+	public String getThing(@PathVariable Long number) {
+		log.info("call numberService to square {}", number);
+		return String.format("{\"square\": %s}", numberService.square(number));
+	}
+
+}

spring-ehcache/src/main/java/com/baeldung/cachetest/service/NumberService.java

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+package com.baeldung.cachetest.service;
+
+import java.math.BigDecimal;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.cache.annotation.Cacheable;
+import org.springframework.stereotype.Service;
+
+@Service
+public class NumberService {
+
+	private final static Logger log = LoggerFactory.getLogger(NumberService.class);
+
+	@Cacheable(value = "squareCache", key = "#number", condition = "#number>10")
+	public BigDecimal square(Long number) {
+		BigDecimal square = BigDecimal.valueOf(number).multiply(BigDecimal.valueOf(number));
+		log.info("square of {} is {}", number, square);
+		return square;
+	}
+
+}