Problem Statement

I have a data provider (basically, system-of-record) which can return me a huge data set. What I want to do is, write these records in a cache, and then, return a set of records page-by-page from the cache. The cache here acts like a buffer to ensure that there is no strain on the memory. In the following example, I have just stopped short of the actual paging solution. Instead I have tried to illustrate how its possible using EhCache.

Maven Configuration

Just putting ehcache and slf4j should be good enough.

      
			net.sf.ehcache
			ehcache
			2.8.3
		
		
			org.slf4j
			slf4j-api
			${slf4j.version}
		
		
			org.slf4j
			slf4j-log4j12
			${slf4j.version}
		
		
			log4j
			log4j
			1.2.14
		

EhCache Configuration

The ehCache configuration file, my-demo-ehcache.xml in this case, looks like:

Getting a handle to the Cache

CacheManager cacheManager = CacheManager.newInstance(CacheBackedRssReader.class.getResource("/my-demo-ehcache.xml"));
Cache cache = cacheManager.getCache("myCache1");

Note that we are loading the ehCache configuration file and then retrieving a cache named myCache1, which I had defined in the configuartion xml.

 Putting stuff into the cache

If you are planning to write this cache on a disk, then you need to make sure that the object that you are storing is Serializable.

        Element cacheElement = new Element("MyIdentifier", mySerializableObject);
        cache.put(cacheElement);

Retrieving stuff from the cache

       Element element = cache.get("MyIdentifier");
       MySerializableObject myObject = (MySerializableObject) element.getObjectValue();

Resources

The sources for this can be found here: https://github.com/paawak/blog/tree/master/code/ehcache-simple