Search

Now that you've experimented with BigMemory's basic CRUD operations, let's take a look at some of the search capabilities.

We will create a data set of Person objects that has some searchable attributes, including height, weight and body mass index.

Create Configuration File

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

<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="http://www.ehcache.org/ehcache.xsd"
     name="SearchConfig" maxBytesLocalHeap="64M">
  <cache name="hello-world"/>
  <cache name="crud"/>
  <cache name="search">
    <searchable>
        <searchAttribute name="height"/>
        <searchAttribute name="weight"/>
        <searchAttribute name="bodyMassIndex" />
    </searchable>
  </cache>
</ehcache>

Create Search.java

Create and compile a Java class called Search:

import net.sf.ehcache.Cache;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Element;
import net.sf.ehcache.search.Attribute;
import net.sf.ehcache.search.Query;
import net.sf.ehcache.search.Result;
import net.sf.ehcache.search.Results;

public class Search {

  public static void main(final String[] args) {

    // Create a cache manager using the factory method...
    final CacheManager cacheManager = CacheManager.newInstance(Crud.class
        .getResource("/ehcache-search.xml"));

    // Retrieve the "search" data set...
    final Cache dataSet = cacheManager.getCache("search");

    // Create some searchable objects...
    final Person janeAusten = new Person(1, "Jane", "Austen", 5 * 12 + 7, 130);
    final Person charlesDickens = new Person(2, "Charles", "Dickens",
        5 * 12 + 9, 160);
    final Person janeDoe = new Person(3, "Jane", "Doe", 5 * 12 + 5, 145);

    // Put the searchable objects into the data set...
    dataSet.put(new Element(janeAusten.getId(), janeAusten));
    dataSet.put(new Element(charlesDickens.getId(), charlesDickens));
    dataSet.put(new Element(janeDoe.getId(), janeDoe));

    // Fetch the Body Mass Index (BMI) attribute...
    Attribute<Object> bmi = dataSet.getSearchAttribute("bodyMassIndex");

    // Create a query for all people with a BMI greater than 23...
    final Query query = dataSet.createQuery().addCriteria(bmi.gt(23F))
        .includeValues();

    // Execute the query...
    final Results results = query.execute();

    // Print the results...
    for (Result result : results.all()) {
      System.out.println(result.getValue());
    }
  }

  public static class Person {
    private final String firstName;
    private final String lastName;
    private final long id;
    private final int height;
    private final int weight;

    public Person(long id, final String firstName, final String lastName,
        final int height, final int weight) {
      this.id = id;
      this.firstName = firstName;
      this.lastName = lastName;
      this.height = height;
      this.weight = weight;
    }

    public String getFirstName() {
      return firstName;
    }

    public String getLastName() {
      return lastName;
    }

    public int getHeight() {
      return height;
    }

    public int getWeight() {
      return weight;
    }

    public float getBodyMassIndex() {
      return ((float) weight / ((float) height * (float) height)) * 703;
    }

    public long getId() {
      return id;
    }

    public String toString() {
      return "[id=" + id + ", firstName=" + firstName + ", lastName="
          + lastName + ", height=" + height + " in" + ", weight=" + weight
          + " lbs" + ", bmi=" + getBodyMassIndex() + "]";
    }
  }

}

Execute

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

[id=2, firstName=Charles, lastName=Dickens, height=69 in, weight=160 lbs, bmi=23.625288]

[id=3, firstName=Jane, lastName=Doe, height=65 in, weight=145 lbs, bmi=24.126627]

Next Step

Next Step: Sorting Results ›