/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2009, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library 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
* Lesser General Public License for more details.
*/
package org.geotools.process.factory;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.geotools.factory.FactoryRegistry;
import org.geotools.feature.NameImpl;
import org.opengis.feature.type.Name;
import org.opengis.util.InternationalString;
/**
* Annotation driven process factory; used to wrap up a bunch of Java beans as a single
* Process Factory.
* <p>
* To make use of this class you will need to:
* <ol>
* <li>Create an instance passing in a list of "bean" classes you wish to publish:<pre>
* ProcessFactory factory = new AnnotatedBeanProcessFactory( Text.text("Internal"),"internal", ExampleProcess);</pre></li>
* <li>Create an implementation of each bean class referenced:
* <ul>
* <li>Annotate the class with {@link DescribeProcess}:<pre> @DescribeProcess( title = "bounds",
* description = "Computes the overlall bounds of the input features")
* public class BoundsProcess {
* ...
* }</pre></li>
* <li>Supply an <b>execute</b> method (which we can call by reflection):<pre> @DescribeResult(name = "bounds",
* description = "The feature collection bounds")
* public ReferencedEnvelope execute( @DescribeParameter(name = "features",
* description = "Collection whose bounds will be computed")
* FeatureCollection features) {
* return features.getBounds();
* }
* </pre></li>
* </ul>
* </li>
* <li>Optional: If you are using this technique in an environment such as Spring you may wish to use a
* "marker interface" to allow Spring to discover implementations on the classpath.<pre>
* public class BoundsProcess implements GeoServerProcess {
* ...
* }
* </pre></li>
* </ol>
*
*
* @source $URL$
*/
public class AnnotatedBeanProcessFactory extends AnnotationDrivenProcessFactory {
Map<String, Class<?>> classMap;
public AnnotatedBeanProcessFactory(InternationalString title, String namespace,
Class<?>... beanClasses) {
super(title, namespace);
classMap = classMap( beanClasses );
}
/**
* Method responsible for using reflection on the list of bean classes and producing
* a map of process names to implementing java bean.
* <p>
* This is isolated as a static method to allow for unit test; it is called by the constructor.
* @param beanClasses
* @return class map from process name to implementing class.
*/
static Map<String, Class<?>> classMap( Class<?>... beanClasses ){
Map<String,Class<?>> map = new HashMap<String, Class<?>>();
for (Class<?> c : beanClasses) {
String name = c.getSimpleName();
if (name.endsWith("Process")) {
name = name.substring(0, name.indexOf("Process"));
}
map.put(name, c);
}
return map;
}
/**
* Used to go through the list of java beans; returning the DescribeProcess
* annotation for each one.
* @param name Process name
* @return DescribeProcess annotation for the named process
*/
@Override
protected DescribeProcess getProcessDescription(Name name) {
Class<?> c = classMap.get(name.getLocalPart());
if (c == null) {
return null;
} else {
return (DescribeProcess) c.getAnnotation(DescribeProcess.class);
}
}
/**
* Resolves to the <b>execute</b> method for the provided java bean.
* @return the "execute" method of the indicated java bean.
*/
@Override
protected Method method(String className) {
Class<?> c = classMap.get(className);
if (c != null) {
List<Method> candidates = new ArrayList<Method>();
for (Method m : c.getMethods()) {
if ("execute".equals(m.getName())) {
candidates.add(m);
}
}
if(candidates.size() == 1) {
return candidates.get(0);
} else if(candidates.size() > 1) {
// uh, we have various methods in overload, we'll prefer the one
// that has annotations and exposes most params
Method selection = null;
for (Method m : candidates) {
if(hasProcessAnnotations(m)) {
if(selection != null) {
throw new IllegalArgumentException("Invalid process bean " + className
+ ", has two annotated execute methods");
} else {
selection = m;
}
}
}
return selection;
}
}
return null;
}
private boolean hasProcessAnnotations(Method m) {
Annotation[] annotations = m.getAnnotations();
if(hasProcessAnnotations(annotations)) {
return true;
}
Annotation[][] paramAnnotations = m.getParameterAnnotations();
for (Annotation[] pa : paramAnnotations) {
if(hasProcessAnnotations(pa)) {
return true;
}
}
return false;
}
private boolean hasProcessAnnotations(Annotation[] annotations) {
for (Annotation annotation : annotations) {
if(annotation instanceof DescribeResult || annotation instanceof DescribeResults || annotation instanceof DescribeParameter) {
return true;
}
}
return false;
}
/**
* List of processes published; generated from the classMap created in the constructuor.
*/
public Set<Name> getNames() {
Set<Name> result = new LinkedHashSet<Name>();
List<String> names = new ArrayList<String>(classMap.keySet());
Collections.sort(names);
for (String name : names) {
result.add(new NameImpl(namespace, name));
}
return result;
}
/**
* Create an instance of the named process bean.
* <p>
* By having an actual object here we allow implementors to hold onto a bit of state if they
* wish. The object will need to have an <n>execute</b> method and be annotated with a
* describe process annotation.
*/
protected Object createProcessBean(Name name) {
try {
Class<?> processClass = classMap.get(name.getLocalPart());
if(processClass == null) {
throw new IllegalArgumentException("Process " + name + " is unknown");
}
return processClass.newInstance();
} catch (InstantiationException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
}
}
/**
* Subclass of FactoryRegistry meant for convenience of looking up all the classes
* that implement a specific bean interface.
*/
public static class BeanFactoryRegistry<T> extends FactoryRegistry {
public BeanFactoryRegistry(Class<T> clazz) {
super(clazz);
}
public Class<T> getBeanClass() {
return (Class<T>) getCategories().next();
}
public Class<? extends T>[] lookupBeanClasses() {
Iterator<T> it = getServiceProviders(getBeanClass(), null, null);
List<Class> list = new ArrayList();
while(it.hasNext()) {
list.add((Class<? extends T>) it.next().getClass());
}
return list.toArray(new Class[list.size()]);
}
}
}