Searching
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://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