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Quick ORM implementation based on the UJO objects.
/*
* Copyright 2007-2010 Pavel Ponec
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.ujoframework.criterion;
import org.ujoframework.Ujo;
import org.ujoframework.UjoProperty;
/**
* An abstract criterion provides a basic interface and static factory methods. You can use it:
*
* - like a generic UJO object validator (2)
* - to create a query on the UJO list (1)
* - the class is used to build 'SQL query' in the module ujo-orm (sience 0.90)
*
*
* There is allowed to join two instances (based on the same BO) to a binary tree by a new Criterion.
* Some common operators (and, or, not) are implemeted into a special join method of the Criteron class.
*
* Example of use
* // Make a criterion:
* Criterion<Person> crn1 = Criterion.newInstance(CASH, Operator.GT, 10.0);
* Criterion<Person> crn2 = Criterion.newInstance(CASH, Operator.LE, 20.0);
* Criterion<Person> criterion = crn1.and(crn2);
*
* // Use a criterion (1):
* CriteriaTool<Person> ct = CriteriaTool.newInstance();
* List<Person> result = ct.select(persons, criterion);
* assertEquals(1, result.size());
* assertEquals(20.0, CASH.of(result.get(0)));
*
* // Use a criterion (2):
* Person person = result.get(0);
* boolean validation = criterion.evaluate(person);
* assertTrue(validation);
*
*
* @since 0.90
* @author Pavel Ponec
* @composed 1 - 1 AbstractOperator
*/
public abstract class Criterion {
public abstract boolean evaluate(UJO ujo);
public Criterion join(BinaryOperator operator, Criterion criterion) {
return new BinaryCriterion(this, operator, criterion);
}
public Criterion and(Criterion criterion) {
return join(BinaryOperator.AND, criterion);
}
public Criterion or(Criterion criterion) {
return join(BinaryOperator.OR, criterion);
}
public Criterion not() {
return new BinaryCriterion(this, BinaryOperator.NOT, this);
}
/** Returns the left node of the parrent */
abstract public Object getLeftNode();
/** Returns the right node of the parrent */
abstract public Object getRightNode();
/** Returns an operator */
abstract public AbstractOperator getOperator();
// ------ STATIC FACTORY --------
/**
* New criterion instance
* @param property UjoProperty
* @param operator Operator
*
* - VALUE - the parameter value
* - UjoProperty - reference to a related entity
* - List<TYPE> - list of values (TODO - this type is planned in the future)
* - THE SAME property - the value will be assigned using the property later (TODO in future)
*
* @return A new criterion
*/
public static Criterion newInstance
( UjoProperty property
, Operator operator
, TYPE value
) {
return new ValueCriterion(property, operator, value);
}
/**
* New criterion instance
* @param property UjoProperty
* @param operator Operator
*
* - VALUE - the parameter value
* - UjoProperty - reference to a related entity
* - List<TYPE> - list of values (TODO - this type is planned in the future)
* - THE SAME property - the value will be assigned using the property later (TODO in future)
*
* @return A new criterion
*/
public static Criterion newInstance
( UjoProperty property
, Operator operator
, UjoProperty value
) {
return new ValueCriterion(property, operator, value);
}
/**
* New equals instance
* @param property UjoProperty
*
* - TYPE - parameter value
* - List<TYPE> - list of values
* - UjoProperty - reference to a related entity
* - THE SAME property - the value will be assigned using the property later
*
* @return A the new Criterion
*/
public static Criterion newInstance
( UjoProperty property
, TYPE value
) {
return new ValueCriterion(property, null, value);
}
/**
* New equals instance
* @param property UjoProperty
* @param value Value or UjoProperty can be type a direct of indirect (for a relation) property
* @return A the new Criterion
*/
public static Criterion newInstance
( UjoProperty property
, UjoProperty value
) {
return new ValueCriterion(property, null, value);
}
/**
* New equals instance
* @param property UjoProperty
*
* - TYPE - parameter value
* - List<TYPE> - list of values
* - UjoProperty - reference to a related entity
* - THE SAME property - the value will be assigned using the property later
*
*/
public static Criterion newInstance(UjoProperty property) {
return new ValueCriterion(property, Operator.EQ, property);
}
/** This is an constane criterion independed on an entity.
* It is recommended not to use this solution in ORM.
*/
@SuppressWarnings("unchecked")
public static Criterion newInstance(boolean value) {
return (Criterion) (value
? ValueCriterion.TRUE
: ValueCriterion.FALSE
);
}
/** This is a constant criterion independed on the property and the ujo entity. A result is the TRUE always. */
public static Criterion newInstanceTrue(UjoProperty property) {
return new ValueCriterion(property, Operator.X_FIXED, true);
}
/** This is a constant criterion independed on the property and the ujo entity. A result is the FALSE always. */
public static Criterion newInstanceFalse(UjoProperty property) {
return new ValueCriterion(property, Operator.X_FIXED, false);
}
/** Is the class a Binary criterion? */
public boolean isBinary() {
return false;
}
}