org.onebusaway.webapp.impl.GWTAbstractFactory.java Source code

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Here is the source code for org.onebusaway.webapp.impl.GWTAbstractFactory.java

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/**
 * Copyright (C) 2011 Brian Ferris <bdferris@onebusaway.org>
 *
 * 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.onebusaway.webapp.impl;

import org.springframework.beans.factory.FactoryBean;

public abstract class GWTAbstractFactory implements FactoryBean {

    protected Class<?> _type;

    private boolean _singleton = false;

    private Object _instance = null;

    private Class<?> _parentType;

    public GWTAbstractFactory(Class<?> parentType) {
        _parentType = parentType;
    }

    public void setType(Class<?> type) {
        if (!_parentType.isAssignableFrom(type))
            throw new IllegalStateException("type is not assignable to " + _parentType);
        _type = type;
    }

    public void setSingleton(boolean singleton) {
        _singleton = singleton;
    }

    /*****************************************************************************
     * {@link FactoryBean} Interface
     ****************************************************************************/

    public Class<?> getObjectType() {
        return _type;
    }

    public boolean isSingleton() {
        return _singleton;
    }

    public synchronized Object getObject() throws Exception {
        if (!_singleton)
            return createInstance();
        if (_instance == null)
            _instance = createInstance();
        return _instance;
    }

    /*****************************************************************************
     * Private Methods
     ****************************************************************************/

    protected abstract Object createInstance() throws Exception;
}