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Its an port to fix bugs in OSGi support. ... The Apache Commons Discovery 0.5 component is about discovering, or finding,
implementations for pluggable interfaces.
/*
* 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.
*
* @param The SPI type
*/
public class SPInterface {
/**
* Construct object representing Class {@code provider}.
*
* @param The SPI type
* @param provider The SPI class
* @return A new object representing Class {@code provider}
* @since 0.5
*/
public static SPInterface newSPInterface(Class provider) {
return newSPInterface(provider, provider.getName());
}
/**
* Construct object representing Class {@code provider}.
*
* @param The SPI type
* @param provider 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 propertyName.
* @return A new object representing Class {@code provider}
* @since 0.5
*/
public static SPInterface newSPInterface(Class provider, String propertyName) {
return new SPInterface(provider, propertyName);
}
/**
* Construct object representing Class {@code provider}.
*
* @param The SPI type
* @param provider The SPI class
* @param constructorParamClasses classes representing the
* constructor argument types
* @param constructorParams objects representing the
* constructor arguments
* @return A new object representing Class {@code provider}
* @since 0.5
*/
public static SPInterface newSPInterface(Class provider,
Class constructorParamClasses[],
Object constructorParams[]) {
return newSPInterface(provider, provider.getName(), constructorParamClasses, constructorParams);
}
/**
* Construct object representing Class {@code provider}.
*
* @param The SPI type
* @param provider 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 propertyName.
* @param constructorParamClasses classes representing the
* constructor argument types
* @param constructorParams objects representing the
* constructor arguments
* @return A new object representing Class {@code provider}
* @since 0.5
*/
public static SPInterface newSPInterface(Class provider,
String propertyName,
Class constructorParamClasses[],
Object constructorParams[]) {
return new SPInterface(provider, propertyName, constructorParamClasses, constructorParams);
}
/**
* 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 final Class paramClasses[];
private final Object params[];
/**
* Construct object representing Class provider.
*
* @param provider The SPI class
*/
public SPInterface(Class provider) {
this(provider, provider.getName());
}
/**
* Construct object representing Class provider.
*
* @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 propertyName.
*/
public SPInterface(Class spi, String propertyName) {
this.spi = spi;
this.propertyName = propertyName;
this.paramClasses = null;
this.params = null;
}
/**
* Construct object representing Class provider.
*
* @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 provider.
*
* @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 propertyName.
*
* @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;
}
/**
* Returns the SPI class name.
*
* @return The SPI class name
*/
public String getSPName() {
return spi.getName();
}
/**
* Returns the SPI class.
*
* @return The SPI class
*/
public Class getSPClass() {
return spi;
}
/**
* Returns the property name to be used for finding
* the name of the SPI implementation class.
*
* @return The property name to be used for finding
* the name of the SPI implementation class
*/
public String getPropertyName() {
return propertyName;
}
/**
* Creates a new instance of the given SPI class.
*
* @param Any type extends T
* @param impl The SPI class has to be instantiated
* @return A new instance of the given SPI class
* @throws DiscoveryException if the class implementing
* the SPI cannot be found, cannot be loaded and
* instantiated, or if the resulting class does not implement
* (or extend) the SPI
* @throws InstantiationException see {@link Class#newInstance()}
* @throws IllegalAccessException see {@link Class#newInstance()}
* @throws NoSuchMethodException see {@link Class#newInstance()}
* @throws InvocationTargetException see {@link Class#newInstance()}
*/
public S newInstance(Class impl)
throws DiscoveryException,
InstantiationException,
IllegalAccessException,
NoSuchMethodException,
InvocationTargetException {
verifyAncestory(impl);
return ClassUtils.newInstance(impl, paramClasses, params);
}
/**
* Verifies the given SPI implementation is a SPI specialization.
*
* @param Any type extends T
* @param impl The SPI instantance
*/
public void verifyAncestory(Class impl) {
ClassUtils.verifyAncestory(spi, impl);
}
}