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Added by Xircles System User, last edited by Anders Norås on Oct 10, 2007  (view change)

Quaere is an open source, extensible framework that adds a querying syntax reminiscent of SQL to Java applications. Quaere allows you to filter, enumerate and create projections over a number of collections and other queryable resources using a common, expressive syntax.

Selecting all integers that are less than five from an array of integers
Integer[] numbers={5, 4, 1, 3, 9, 8, 7, 2, 0};
Iterable<Integer> lowNumbers=
        from("n").in(numbers).
        where(lt("n",5).
        select("n");

System.out.println("All numbers that are less than five:")
for (Integer n: lowNumbers) {
    System.out.println(n);
}

Quaere detaches queries from the query API used by different queryable resources such as databases, catalogs and other structured data, allowing one language to be used to query numerous resources.

Selecting all customers in the Washington region from a database
// Setup a JPA entity manager...
SessionFactory sessionFactory=new Configuration().configure().buildSessionFactory();
EntityManagerFactory entityManagerFactory = 
    new EntityManagerFactoryImpl(sessionFactory, PersistenceUnitTransactionType.RESOURCE_LOCAL, true);
QueryableEntityManager entityManager = 
    new QueryableEntityManager(entityManagerFactory.createEntityManager());

// Select all customers in the Washington region
Iterable<Customer> waCustomers =
        from("c").in(entityManager.entity(Customer.class)).
        where(eq("c.getRegion()", "WA")).
        select("c");

System.out.println("These customers are located in the Washington region:");
for (Customer c : waCustomers) {
    System.out.println(c.getCompanyName());
}

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