org.hibernate.transform.AliasToBeanResultTransformer.java Source code

Introduction

Here is the source code for org.hibernate.transform.AliasToBeanResultTransformer.java

Source

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.transform;

import java.util.Arrays;

import org.hibernate.HibernateException;
import org.hibernate.property.access.internal.PropertyAccessStrategyBasicImpl;
import org.hibernate.property.access.internal.PropertyAccessStrategyChainedImpl;
import org.hibernate.property.access.internal.PropertyAccessStrategyFieldImpl;
import org.hibernate.property.access.internal.PropertyAccessStrategyMapImpl;
import org.hibernate.property.access.spi.Setter;

/**
 * Result transformer that allows to transform a result to
 * a user specified class which will be populated via setter
 * methods or fields matching the alias names.
 * <p/>
 * <pre>
 * List resultWithAliasedBean = s.createCriteria(Enrolment.class)
 *          .createAlias("student", "st")
 *          .createAlias("course", "co")
 *          .setProjection( Projections.projectionList()
 *                .add( Projections.property("co.description"), "courseDescription" )
 *          )
 *          .setResultTransformer( new AliasToBeanResultTransformer(StudentDTO.class) )
 *          .list();
 * <p/>
 *  StudentDTO dto = (StudentDTO)resultWithAliasedBean.get(0);
 *    </pre>
 *
 * @author max
 */
public class AliasToBeanResultTransformer extends AliasedTupleSubsetResultTransformer {

    // IMPL NOTE : due to the delayed population of setters (setters cached
    //       for performance), we really cannot properly define equality for
    //       this transformer

    private final Class resultClass;
    private boolean isInitialized;
    private String[] aliases;
    private Setter[] setters;

    public AliasToBeanResultTransformer(Class resultClass) {
        if (resultClass == null) {
            throw new IllegalArgumentException("resultClass cannot be null");
        }
        isInitialized = false;
        this.resultClass = resultClass;
    }

    @Override
    public boolean isTransformedValueATupleElement(String[] aliases, int tupleLength) {
        return false;
    }

    @Override
    public Object transformTuple(Object[] tuple, String[] aliases) {
        Object result;

        try {
            if (!isInitialized) {
                initialize(aliases);
            } else {
                check(aliases);
            }

            result = resultClass.newInstance();

            for (int i = 0; i < aliases.length; i++) {
                if (setters[i] != null) {
                    setters[i].set(result, tuple[i], null);
                }
            }
        } catch (InstantiationException e) {
            throw new HibernateException("Could not instantiate resultclass: " + resultClass.getName());
        } catch (IllegalAccessException e) {
            throw new HibernateException("Could not instantiate resultclass: " + resultClass.getName());
        }

        return result;
    }

    private void initialize(String[] aliases) {
        PropertyAccessStrategyChainedImpl propertyAccessStrategy = new PropertyAccessStrategyChainedImpl(
                PropertyAccessStrategyBasicImpl.INSTANCE, PropertyAccessStrategyFieldImpl.INSTANCE,
                PropertyAccessStrategyMapImpl.INSTANCE);
        this.aliases = new String[aliases.length];
        setters = new Setter[aliases.length];
        for (int i = 0; i < aliases.length; i++) {
            String alias = aliases[i];
            if (alias != null) {
                this.aliases[i] = alias;
                setters[i] = propertyAccessStrategy.buildPropertyAccess(resultClass, alias).getSetter();
            }
        }
        isInitialized = true;
    }

    private void check(String[] aliases) {
        if (!Arrays.equals(aliases, this.aliases)) {
            throw new IllegalStateException("aliases are different from what is cached; aliases="
                    + Arrays.asList(aliases) + " cached=" + Arrays.asList(this.aliases));
        }
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        AliasToBeanResultTransformer that = (AliasToBeanResultTransformer) o;

        if (!resultClass.equals(that.resultClass)) {
            return false;
        }
        if (!Arrays.equals(aliases, that.aliases)) {
            return false;
        }

        return true;
    }

    @Override
    public int hashCode() {
        int result = resultClass.hashCode();
        result = 31 * result + (aliases != null ? Arrays.hashCode(aliases) : 0);
        return result;
    }
}