Basic CRUD

Now that you've created your first instance of BigMemory with the Ehcache interface, let's exercise its basic CRUD functions.

Create Configuration File

Create a new configuration file called "ehcache-crud.xml" in your classpath and add a new cache called "crud."

<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="http://www.ehcache.org/ehcache.xsd"
     name="CRUDConfig" maxBytesLocalHeap="64M">
  <cache name="hello-world"/>
  <cache name="crud"/>
</ehcache>

(Notice that the maxByteLocalHeap setting has been moved to the top-level <ehcache> element—BigMemory gives you the ability to sculpt the memomory profile of your individual data sets as well as apply bulk settings to all data sets.)

Create Crud.java

Create and compile a Java class called Crud:

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

public class Crud {
    public static void main(final String[] args) {
        // Create a cache manager using the factory method
        // AND specify the new configuration file
        final CacheManager cacheManager = 
              CacheManager.newInstance(
                Crud.class.getResource("/ehcache-crud.xml"));

        // Get the "crud" cache from the cache manager...
        final Cache dataStore = cacheManager.getCache("crud");

        // Set up the first data element...
        final String myKey = "My Key";
        final String myData = "My Data";
        final Element createElement = new Element(myKey, myData);

        // CREATE data using the put(Element) method...
        dataStore.put(createElement);
        System.out.println("Created data: " + createElement);

        // READ data using the get(Object) method...
        Element readElement = dataStore.get(myKey);
        System.out.println("Read data:    " + readElement);

        // Check to make sure the data is the same...
        if (! myData.equals(readElement.getObjectValue())) {
            throw new RuntimeException("My data doesn't match!");
        }

        // UPDATE data by mapping a new value to the same key...
        final String myNewData = "My New Data";
        final Element updateElement = new Element(myKey, myNewData);
        dataStore.put(updateElement);
        System.out.println("Updated data: " + updateElement);

        // Test to see that the data is updated...
        readElement = dataStore.get(myKey);
        if (! myNewData.equals(readElement.getObjectValue())) {
            throw new RuntimeException("My data doesn't match!");
        }

        // DELETE data using the remove(Object) method...
        final boolean wasRemoved = dataStore.remove(myKey);
        System.out.println("Removed data: " + wasRemoved);
        if (! wasRemoved) {
            throw new RuntimeException("My data wasn't removed!");
        }

        // Be polite and release the CacheManager resources...
        cacheManager.shutdown();
    }
}

Execute

When you run the Crud program in a terminal, you should see output like this:

Created data: [ key = My Key, value=My Data, version=1, hitCount=0,
 
          CreationTime = 1361401376761, LastAccessTime = 1361401376761 ]

Read data:    [ key = My Key, value=My Data, version=1, hitCount=1, 

          CreationTime = 1361401376761, LastAccessTime = 1361401376775 ]

Updated data: [ key = My Key, value=My New Data, version=1, hitCount=0, 

          CreationTime = 1361401376776, LastAccessTime = 1361401376776 ]

Removed data: true

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