ConstructorMethodImpl.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.felix.scr.impl.inject;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.util.Map;

import org.apache.felix.scr.impl.inject.ValueUtils.ValueType;
import org.apache.felix.scr.impl.inject.field.FieldUtils;
import org.apache.felix.scr.impl.manager.ComponentContextImpl;
import org.apache.felix.scr.impl.metadata.ReferenceMetadata;

/**
 * This implementation is used to construct a component instance object,
 * call the constructor and set the activation fields.
 */
public class ConstructorMethodImpl<T> implements ConstructorMethod<T>
{
    private volatile boolean m_initialized = false;

    private volatile ValueType[] m_paramTypes;
    private volatile Field[] m_fields;

    private volatile Constructor<T> m_constructor;
    private volatile ValueType[] m_constructorArgTypes;

    @SuppressWarnings("unchecked")
    @Override
    public <S> T newInstance(Class<T> componentClass,
            ComponentContextImpl<T> componentContext,
            Map<Integer, ReferencePair<S>> parameterMap)
    throws Exception
    {
        if ( !m_initialized ) {
            // activation fields
            if ( componentContext.getComponentMetadata().getActivationFields() != null )
            {
                m_paramTypes = new ValueType[componentContext.getComponentMetadata().getActivationFields().size()];
                m_fields = new Field[m_paramTypes.length];

                int index = 0;
                for(final String fieldName : componentContext.getComponentMetadata().getActivationFields() )
                {
                    final FieldUtils.FieldSearchResult result = FieldUtils.searchField(componentClass, fieldName, componentContext.getLogger());
                    if ( result == null || result.field == null )
                    {
                        m_paramTypes[index] = null;
                        m_fields[index] = null;
                    }
                    else
                    {
                        if ( result.usable )
                        {
                            m_paramTypes[index] = ValueUtils.getValueType(result.field.getType());
                            m_fields[index] = result.field;
                        }
                        else
                        {
                            m_paramTypes[index] = ValueType.ignore;
                            m_fields[index] = null;
                        }
                    }
                    index++;
                }
            }
            else
            {
                m_paramTypes = ValueUtils.EMPTY_VALUE_TYPES;
                m_fields = null;
            }
            // constructor injection
            if ( componentContext.getComponentMetadata().isActivateConstructor() )
            {
                // TODO search constructor
                m_constructor = null;

                boolean hasFailure = false;
                final Class<?>[] argTypes = m_constructor.getParameterTypes();
                m_constructorArgTypes = new ValueType[argTypes.length];
                for(int i=0;i<m_constructorArgTypes.length;i++)
                {
                    final ReferencePair<S> pair = parameterMap.get(i);
                    ReferenceMetadata reference = pair == null ? null : pair.dependencyManager.getReferenceMetadata();
                    if ( reference == null )
                    {
                        m_constructorArgTypes[i] = ValueUtils.getValueType(argTypes[i]);
                    }
                    else
                    {
                        m_constructorArgTypes[i] = ValueUtils.getReferenceValueType(componentClass, reference, argTypes[i], null, componentContext.getLogger());
                    }
                    if ( m_constructorArgTypes[i] == ValueType.ignore )
                    {
                        hasFailure = true;
                        break;
                    }
                }
                if ( hasFailure )
                {
                    m_constructor = null;
                }
            }

            // done
            m_initialized = true;
        }

        // if we have fields and one is in state failure (type == null) we can directly throw
        int index = 0;
        for(final ValueType t : m_paramTypes)
        {
            if ( t == null )
            {
                throw new InstantiationException("Field " + componentContext.getComponentMetadata().getActivationFields().get(index)
                        + " not found; Component will fail");
            }
            index++;
        }

        // constructor
        final T component;
        if ( componentContext.getComponentMetadata().isActivateConstructor() )
        {
            if ( m_constructor == null )
            {
                throw new InstantiationException("Constructor not found; Component will fail");
            }
            final Object[] args = new Object[m_constructorArgTypes.length];
            for(int i=0; i<args.length; i++)
            {
                // TODO - get ref pair
                final ReferencePair<S> pair = parameterMap.get(i);
                args[i] = ValueUtils.getValue(componentClass.getName(),
                        m_constructorArgTypes[i],
                        m_constructor.getParameterTypes()[i],
                        componentContext,
                        null);
            }
            component = m_constructor.newInstance(args);
        }
        else
        {
            component = (T)ConstructorMethod.DEFAULT.newInstance((Class<Object>)componentClass,
                    (ComponentContextImpl<Object>)componentContext, null);
        }

        // activation fields
        for(int i = 0; i<m_paramTypes.length; i++)
        {
            if ( m_paramTypes[i] != ValueType.ignore )
            {
                final Object value = ValueUtils.getValue(componentClass.getName(),
                        m_paramTypes[i],
                        m_fields[i].getType(),
                        componentContext,
                        null);
                FieldUtils.setField(m_fields[i], component, value, componentContext.getLogger());
            }
        }

        return component;
    }
}