ORM module of the UJO Framework
am easy to use implementation of the object-relation mapping
- framework has a type safe query language which allows the java compiler find a syntax error similar like a 4GL language
- never more a LazyInitialization exception though a lazy initialization is supported
- no confusing proxy business objects
- no list properties are supported but a special object called
UjoIteratoris designed for a collection. The UjoIterator provides a toList() method however - easy to configure the ORM model by java source code, optionaly by annotations or a XML file
- very small framework without more library dependencies, the current size of the JAR file is around 160 kB
- great performance mainly for the SQL SELECT statement
- all persistent objects are based on the
OrmUjointerface, namely on theOrmTableimplementation - resources for ORM mapping can be a database table, view, or your own SQL SELECT
- default ORM mapping is described by
UjoPropertieshowever there is possible overwrite the mapping by annotations and the annotations can be overwrited by a XML files - JDBC query parameters are passed by a question notation to the PreparedStatement for a high security
- internal object cache is based on the WeakHashMap class so that large transactions does not cause any OutOfMemoryException
- the API was inspired by ORM frameworks Cayenne and Hibernate
A sample of use
See how to create database and to how to INSERT an order with two items into database:
OrmHandler.getInstance().loadDatabase(Database.class);
Order order = new Order();
order.setDate(new Date());
order.setDescr("John's order");
Item item1 = new Item();
item1.setOrder(order);
item1.setDescr("Yellow table");
Item item2 = new Item();
item2.setOrder(order);
item2.setDescr("Green window");
Session session = OrmHandler.getInstance().getSession();
session.save(order);
session.save(item1);
session.save(item2);
session.commit();
The next source code calls a SELECT by the UJO Criteria:
Criterion<Order> criter1 = Criterion.newInstance(Order.DESCR, "John's order");
Criterion<Order> criter2 = Criterion.newInstance(Order.DATE, Operator.LE, new Date());
Criterion<Order> criterion = criter1.and(criter2);
Session session = OrmHandler.getInstance().getSession();
UjoIterator<Order> orders = session.createQuery(criterion).iterate();
System.out.println("ORDER COUNT: " + orders.count()); // method calls SQL SELECT COUNT(*) in case the iterator can provide first item!
for (Order order : orders) {
String descr = order.getDescr();
System.out.println("ORDER ROW: " + order + " // descr: " + descr);
}
The next source code calls a SELECT by an UJO object relation:
Session session = OrmHandler.getInstance().getSession();
Database db = session.getDatabase();
UjoIterator<Order> orders = db.get(Database.ORDERS);
for (Order order : orders) {
String descr = order.getDescr();
System.out.println("Order: " + order + " // descr: " + descr);
for (Item item : order.getItems()) {
Long itemId = item.getId();
String itemDescr = item.getDescr();
System.out.println(" Item id: " + itemId + " descr: " + itemDescr);
}
}
More sources:
License:
- UJO Framework has a license Apache License, Version 2.0
- no more dependences