org.apache.commons.discovery.tools.SPInterface.java Source code

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Here is the source code for org.apache.commons.discovery.tools.SPInterface.java

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/*
 * 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.commons.discovery.tools;

import java.lang.reflect.InvocationTargetException;

import org.apache.commons.discovery.DiscoveryException;

/**
 * Represents a Service Programming Interface (spi).
 * - SPI's name
 * - SPI's (provider) class
 * - SPI's (alternate) override property name
 * 
 * In addition, while there are many cases where this is NOT
 * usefull, for those in which it is:
 * 
 * - expected constructor argument types and parameters values.
 * 
 * @author Richard A. Sitze
 */
public class SPInterface {
    /**
     * The service programming interface: intended to be
     * an interface or abstract class, but not limited
     * to those two.
     */
    private final Class spi;

    /**
     * The property name to be used for finding the name of
     * the SPI implementation class.
     */
    private final String propertyName;

    private Class paramClasses[] = null;
    private Object params[] = null;

    /**
     * Construct object representing Class <code>provider</code>.
     * 
     * @param provider The SPI class
     */
    public SPInterface(Class provider) {
        this(provider, provider.getName());
    }

    /**
     * Construct object representing Class <code>provider</code>.
     * 
     * @param spi The SPI class
     * 
     * @param propertyName when looking for the name of a class implementing
     *        the provider class, a discovery strategy may involve looking for
     *        (system or other) properties having either the name of the class
     *        (provider) or the <code>propertyName</code>.
     */
    public SPInterface(Class spi, String propertyName) {
        this.spi = spi;
        this.propertyName = propertyName;
    }

    /**
     * Construct object representing Class <code>provider</code>.
     * 
     * @param provider The SPI class
     * 
     * @param constructorParamClasses classes representing the
     *        constructor argument types.
     * 
     * @param constructorParams objects representing the
     *        constructor arguments.
     */
    public SPInterface(Class provider, Class constructorParamClasses[], Object constructorParams[]) {
        this(provider, provider.getName(), constructorParamClasses, constructorParams);
    }

    /**
     * Construct object representing Class <code>provider</code>.
     * 
     * @param spi The SPI class
     * 
     * @param propertyName when looking for the name of a class implementing
     *        the provider class, a discovery strategy may involve looking for
     *        (system or other) properties having either the name of the class
     *        (provider) or the <code>propertyName</code>.
     * 
     * @param constructorParamClasses classes representing the
     *        constructor argument types.
     * 
     * @param constructorParams objects representing the
     *        constructor arguments.
     */
    public SPInterface(Class spi, String propertyName, Class constructorParamClasses[],
            Object constructorParams[]) {
        this.spi = spi;
        this.propertyName = propertyName;
        this.paramClasses = constructorParamClasses;
        this.params = constructorParams;
    }

    public String getSPName() {
        return spi.getName();
    }

    public Class getSPClass() {
        return spi;
    }

    public String getPropertyName() {
        return propertyName;
    }

    /**
     * Instantiate a new 
     */
    public Object newInstance(Class impl) throws DiscoveryException, InstantiationException, IllegalAccessException,
            NoSuchMethodException, InvocationTargetException {
        verifyAncestory(impl);

        return ClassUtils.newInstance(impl, paramClasses, params);
    }

    public void verifyAncestory(Class impl) {
        ClassUtils.verifyAncestory(spi, impl);
    }
}