Java tutorial
/******************************************************************************* * Copyright (c) 2014 antoniomariasanchez at gmail.com. * All rights reserved. This program and the accompanying materials * are made available under the terms of the GNU Public License v3.0 * which accompanies this distribution, and is available at * http://www.gnu.org/licenses/gpl.html * * Contributors: * antoniomaria - initial API and implementation ******************************************************************************/ package net.sf.gazpachoquest.qbe; import static javax.persistence.metamodel.Attribute.PersistentAttributeType.EMBEDDED; import static javax.persistence.metamodel.Attribute.PersistentAttributeType.MANY_TO_ONE; import static javax.persistence.metamodel.Attribute.PersistentAttributeType.ONE_TO_ONE; import static org.apache.commons.lang3.StringUtils.isNotEmpty; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.ArrayList; import java.util.List; import java.util.Map; import java.util.Set; import javax.persistence.EntityManager; import javax.persistence.criteria.CriteriaBuilder; import javax.persistence.criteria.CriteriaQuery; import javax.persistence.criteria.ListJoin; import javax.persistence.criteria.Path; import javax.persistence.criteria.Predicate; import javax.persistence.criteria.Root; import javax.persistence.criteria.SetJoin; import javax.persistence.metamodel.Attribute; import javax.persistence.metamodel.ManagedType; import javax.persistence.metamodel.PluralAttribute; import javax.persistence.metamodel.SingularAttribute; import net.sf.gazpachoquest.domain.support.Persistable; import org.apache.commons.lang3.Validate; import org.eclipse.persistence.indirection.ValueHolderInterface; import org.springframework.data.jpa.domain.Specification; import org.springframework.util.ReflectionUtils; public class ByExampleSpecification { private final EntityManager em; public ByExampleSpecification(final EntityManager em) { this.em = em; } public <T extends Persistable> Specification<T> byExampleOnEntity(final T example, final SearchParameters sp) { Validate.notNull(example, "example must not be null"); return new Specification<T>() { @Override public Predicate toPredicate(final Root<T> rootPath, final CriteriaQuery<?> query, final CriteriaBuilder builder) { Class<T> type = rootPath.getModel().getBindableJavaType(); ManagedType<T> mt = em.getMetamodel().entity(type); List<Predicate> predicates = new ArrayList<Predicate>(); predicates.addAll(byExample(mt, rootPath, example, sp, builder)); predicates.addAll(byExampleOnXToOne(mt, rootPath, example, sp, builder)); // 1 level deep only predicates.addAll(byExampleOnManyToMany(mt, rootPath, example, sp, builder)); // order by query.orderBy(JpaUtil.buildJpaOrders(sp.getOrders(), rootPath, builder)); return JpaUtil.andPredicate(builder, predicates); } //https://github.com/jaxio/generated-projects/tree/master/jsf2-spring-conversation/src/main/generated-java/com/jaxio/appli/repository/support public <T extends Persistable> List<Predicate> byExample(final ManagedType<T> mt, final Path<T> mtPath, final T mtValue, final SearchParameters sp, final CriteriaBuilder builder) { List<Predicate> predicates = new ArrayList<Predicate>(); for (SingularAttribute<? super T, ?> attr : mt.getSingularAttributes()) { if (attr.getPersistentAttributeType() == MANY_TO_ONE || attr.getPersistentAttributeType() == ONE_TO_ONE || attr.getPersistentAttributeType() == EMBEDDED || attr.getJavaType().isAssignableFrom(Map.class)) { continue; } Object attrValue = getValue(mtValue, attr); if (attrValue != null) { if (attr.getJavaType() == String.class) { if (isNotEmpty((String) attrValue)) { SingularAttribute<? super T, String> stringAttribute = mt .getSingularAttribute(attr.getName(), String.class); predicates.add(JpaUtil.stringPredicate(mtPath.get(stringAttribute), attrValue, sp, builder)); } } else { SingularAttribute<? super T, ?> attribute = mt.getSingularAttribute(attr.getName(), attr.getJavaType()); // apply equal predicates.add(builder.equal(mtPath.get(attribute), attrValue)); } } } return predicates; } /** * Construct a join predicate on collection (eg many to many, List) */ public <T extends Persistable> List<Predicate> byExampleOnManyToMany(final ManagedType<T> mt, final Root<T> mtPath, final T mtValue, final SearchParameters sp, final CriteriaBuilder builder) { List<Predicate> predicates = new ArrayList<Predicate>(); for (PluralAttribute<T, ?, ?> pa : mt.getDeclaredPluralAttributes()) { if (pa.getCollectionType() == PluralAttribute.CollectionType.LIST) { List<?> value = (List<?>) getValue(mtValue, mt.getAttribute(pa.getName())); if (value != null && !value.isEmpty()) { ListJoin<T, ?> join = mtPath.join(mt.getDeclaredList(pa.getName())); predicates.add(join.in(value)); } } if (pa.getCollectionType() == PluralAttribute.CollectionType.SET) { Set<?> value = (Set<?>) getValue(mtValue, mt.getAttribute(pa.getName())); if (value != null && !value.isEmpty()) { SetJoin<T, ?> join = mtPath.join(mt.getDeclaredSet(pa.getName())); predicates.add(join.in(value)); } } } return predicates; } /** * Invoke byExample method for each not null x-to-one association * when their pk is not set. This allows you * to search entities based on an associated entity's properties * value. */ @SuppressWarnings("unchecked") public <T extends Persistable, M2O extends Persistable> List<Predicate> byExampleOnXToOne( final ManagedType<T> mt, final Root<T> mtPath, final T mtValue, final SearchParameters sp, final CriteriaBuilder builder) { List<Predicate> predicates = new ArrayList<Predicate>(); for (SingularAttribute<? super T, ?> attr : mt.getSingularAttributes()) { if (attr.getPersistentAttributeType() == MANY_TO_ONE || attr.getPersistentAttributeType() == ONE_TO_ONE) { // M2O m2oValue = (M2O) getValue(mtValue, mt.getAttribute(attr.getName())); if (m2oValue != null) { Class<M2O> m2oType = (Class<M2O>) attr.getBindableJavaType(); ManagedType<M2O> m2oMt = em.getMetamodel().entity(m2oType); Path<M2O> m2oPath = (Path<M2O>) mtPath.get(attr); predicates.addAll(byExample(m2oMt, m2oPath, m2oValue, sp, builder)); } } } return predicates; } private <T> Object getValue(final T example, final Attribute<? super T, ?> attr) { Object value = null; try { if (attr.getJavaMember() instanceof Method) { value = ((Method) attr.getJavaMember()).invoke(example, new Object[0]); } else if (attr.getJavaMember() instanceof Field) { value = ReflectionUtils.getField((Field) attr.getJavaMember(), example); } if (value instanceof ValueHolderInterface) { value = ((ValueHolderInterface) value).getValue(); } } catch (IllegalAccessException e) { throw new RuntimeException(e); } catch (InvocationTargetException e) { throw new RuntimeException(e); } return value; } }; } }