Ehcache hello world example

In this tutorial, we will show you two examples to help you getting started with Ehcache.

Tools used :

1. Ehcache 2.9
2. Maven 3
3. Gradle 2
4. JDK 1.7

P.S Ehcache required JDK 1.5 or above.

1. Project Directory Structure

.
├── build.gradle
├── pom.xml
├── README.md
├── src
│   └── main
│       ├── java
│       │   └── com
│       │       └── favtuts
│       │           └── cache
│       │               └── HelloEhCache.java
│       └── resources
│           └── ehcache.xml
└── target

2. Hello World

Assume this is a Maven project :

pom.xml

	<dependency>
		<groupId>net.sf.ehcache</groupId>
		<artifactId>ehcache</artifactId>
		<version>2.9.0</version>
	</dependency>

Read comments for self-explanatory.

HelloEhCache.java

package com.favtuts.cache;

import net.sf.ehcache.Cache;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Element;

public class HelloEhCache{
	
	public static void main(String[] args) {
		
		//1. Create a cache manager
		CacheManager cm = CacheManager.getInstance();
		
		//2. Create a cache called "cache1"
		cm.addCache("cache1");
		
		//3. Get a cache called "cache1"
		Cache cache = cm.getCache("cache1");
		
		//4. Put few elements in cache
		cache.put(new Element("1","Jan"));
		cache.put(new Element("2","Feb"));
		cache.put(new Element("3","Mar"));
		
		//5. Get element from cache
		Element ele = cache.get("1");
		
		//6. Print out the element
		String output = (ele == null ? null : ele.getObjectValue().toString());
		System.out.println(output);
		
		//7. Is key in cache?
		System.out.println(cache.isKeyInCache("1"));
		System.out.println(cache.isKeyInCache("5"));
		
		//8. shut down the cache manager
		cm.shutdown();
		
	}
	
}

Output

06:03:37.007 [main] WARN  n.s.e.config.ConfigurationFactory - No configuration found. 
	Configuring ehcache from ehcache-failsafe.xml  found in the classpath: 
//...

Jan
true
false

//...

Note

More APIs info, refer to this Performing Basic Cache Operations

Note

The Ehcache framework can be configured via ehcache.xml file, if this file is not available, a default ehcache-failsafe.xml will be used.

2. Ehcache Configuration

In this example, we will show you how to configure Ehcache via an ehcache.xml file.

Assume this is a Gradle project :

gradle.build

apply plugin: 'java'
apply plugin: 'eclipse-wtp'
 
version = '1.0'

// Uses JDK 7
sourceCompatibility = 1.7
targetCompatibility = 1.7

// Get dependencies from Maven central repository
repositories {
	mavenCentral()
}
 
//Project dependencies
dependencies {
	compile 'net.sf.ehcache:ehcache:2.9.0'
}

Create an ehcache.xml, and put it into the src/main/resources folder.

src/main/resources/ehcache.xml

<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:noNamespaceSchemaLocation="ehcache.xsd" updateCheck="true"
	monitoring="autodetect" dynamicConfig="true">

	<!-- By default, Ehcache stored the cached files in temp folder. -->
	<!-- <diskStore path="java.io.tmpdir" /> -->
	
	<!-- Ask Ehcache to store cache in this path -->
	<diskStore path="c:\\cache" />

	<!-- Sample cache named cache1
    This cache contains a maximum in memory of 10000 elements, and will expire
    an element if it is idle for more than 5 minutes and lives for more than
    10 minutes.

    If there are more than 10000 elements it will overflow to the
    disk cache, which in this configuration will go to wherever java.io.tmp is
    defined on your system. On a standard Linux system this will be /tmp" -->
	<cache name="cache1" 
		maxEntriesLocalHeap="10000"
		maxEntriesLocalDisk="1000" 
		eternal="false" 
		diskSpoolBufferSizeMB="20"
		timeToIdleSeconds="300" timeToLiveSeconds="600"
		memoryStoreEvictionPolicy="LFU" 
		transactionalMode="off">
		<persistence strategy="localTempSwap" />
	</cache>

</ehcache>

To understand more, read this official ehcache.xml example.

HelloEhCache.java

package com.favtuts.cache;

import net.sf.ehcache.Cache;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Element;

public class HelloEhCache{
	
	public static void main(String[] args) {
		
		//1. Create a cache manager
		CacheManager cm = CacheManager.newInstance();
		
		//cm.addCache("cache1");
		
		//2. Get a cache called "cache1", declared in ehcache.xml
		Cache cache = cm.getCache("cache1");
		
		//3. Put few elements in cache
		cache.put(new Element("1","Jan"));
		cache.put(new Element("2","Feb"));
		cache.put(new Element("3","Mar"));
		
		//4. Get element from cache
		Element ele = cache.get("2");
		
		//5. Print out the element
		String output = (ele == null ? null : ele.getObjectValue().toString());
		System.out.println(output);
		
		//6. Is key in cache?
		System.out.println(cache.isKeyInCache("3"));
		System.out.println(cache.isKeyInCache("10"));
		
		//7. shut down the cache manager
		cm.shutdown();
		
	}
	
}

Output

06:45:56.294 [main] DEBUG n.s.e.config.ConfigurationFactory - 
  Configuring ehcache from ehcache.xml found in the classpath: 
  file:/C:/Users/mkyong/workspace2/JavaCache/target/classes/ehcache.xml
//...

Feb
true
false

//...

Note

More info about Loading a Configuration

Download Source Code

$ git clone https://github.com/favtuts/java-core-tutorials-examples.git
$ cd java-caching/ehcache-hello

References

1. Ehcache documentation
2. ehcache.xml examples
3. Wikipedia : Ehcache
4. Java – Read A File From Resources Folder
5. Ehcache Logging example
6. Spring Caching and Ehcache example