org.fabric3.implementation.system.introspection.SystemConstructorHeuristic Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of fabric3-system Show documentation
Fabric3 System Implementation Type.
The newest version!
/*
* Fabric3
* Copyright (c) 2009-2013 Metaform Systems
*
* Fabric3 is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as
* published by the Free Software Foundation, either version 3 of
* the License, or (at your option) any later version, with the
* following exception:
*
* Linking this software statically or dynamically with other
* modules is making a combined work based on this software.
* Thus, the terms and conditions of the GNU General Public
* License cover the whole combination.
*
* As a special exception, the copyright holders of this software
* give you permission to link this software with independent
* modules to produce an executable, regardless of the license
* terms of these independent modules, and to copy and distribute
* the resulting executable under terms of your choice, provided
* that you also meet, for each linked independent module, the
* terms and conditions of the license of that module. An
* independent module is a module which is not derived from or
* based on this software. If you modify this software, you may
* extend this exception to your version of the software, but
* you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version.
*
* Fabric3 is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the
* GNU General Public License along with Fabric3.
* If not, see .
*/
package org.fabric3.implementation.system.introspection;

import java.lang.reflect.Constructor;

import org.fabric3.spi.introspection.IntrospectionContext;
import org.fabric3.spi.introspection.java.HeuristicProcessor;
import org.fabric3.spi.introspection.java.NoConstructorFound;
import org.fabric3.spi.introspection.java.annotation.AmbiguousConstructor;
import org.fabric3.spi.model.type.java.InjectingComponentType;
import org.fabric3.spi.model.type.java.Signature;

/**
 * Heuristic that selects the constructor to use.
 */
public class SystemConstructorHeuristic implements HeuristicProcessor {

    public void applyHeuristics(InjectingComponentType componentType, Class implClass, IntrospectionContext context) {
        // if there is already a defined constructor then do nothing
        if (componentType.getConstructor() != null) {
            return;
        }

        Signature signature = findConstructor(implClass, componentType, context);
        componentType.setConstructor(signature);
    }

    /**
     * Find the constructor to use.
     * 
     * For now, we require that the class have a single constructor or one annotated with @Constructor. If there is more than one, the default
     * constructor will be selected or an org.osoa.sca.annotations.Constructor annotation must be used.
     *
     * @param implClass     the class we are inspecting
     * @param componentType the parent component type
     * @param context       the introspection context to report errors and warnings
     * @return the signature of the constructor to use
     */
    Signature findConstructor(Class implClass, InjectingComponentType componentType, IntrospectionContext context) {
        Constructor[] constructors = implClass.getDeclaredConstructors();
        Constructor selected = null;
        if (constructors.length == 1) {
            selected = constructors[0];
        } else {
            for (Constructor constructor : constructors) {
                if (constructor.isAnnotationPresent(org.oasisopen.sca.annotation.Constructor.class)) {
                    if (selected != null) {
                        context.addError(new AmbiguousConstructor(implClass, componentType));
                        return null;
                    }
                    selected = constructor;
                }
            }
            if (selected == null) {
                try {
                    selected = implClass.getConstructor();
                } catch (NoSuchMethodException e) {
                    context.addError(new NoConstructorFound(implClass, componentType));
                    return null;
                }
            }
        }
        return new Signature(selected);
    }

}