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/*
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership.
*
* This 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; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.xwiki.velocity.introspection;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.apache.commons.lang3.StringUtils;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.util.ClassUtils;
import org.apache.velocity.util.RuntimeServicesAware;
import org.apache.velocity.util.introspection.Info;
import org.apache.velocity.util.introspection.Uberspect;
import org.apache.velocity.util.introspection.UberspectImpl;
import org.apache.velocity.util.introspection.UberspectLoggable;
import org.apache.velocity.util.introspection.VelMethod;
import org.apache.velocity.util.introspection.VelPropertyGet;
import org.apache.velocity.util.introspection.VelPropertySet;
/**
*
* Since the current version of the Velocity engine (1.5) does not allow more than one uberspector, this class is a
* workaround. It manually constructs an array of uberspectors, loading the classes in the order
* defined in the "runtime.introspector.uberspect.arrayClasses" property, and after that forwards calls to
* each of the uberspectors, in order, until one of them returns something different than null. Note that
* the calls will be made from the leftmost class to the rightmost one. This allows building and combining different
* small uberspectors that perform a specialised search for methods, instead of bloating a single class with different
* introspection tricks.
*
*
* This is not actually part of the array, but is more of a handle that allows the calls intended for only one
* uberspector to reach the array. It duplicates some of the code from the velocity runtime initialization code, hoping
* that a future version of the engine will support this natively.
*
*
* The array is defined using the configuration parameter runtime.introspector.uberspect.arrayClasses. This
* property should contain a list of canonical class names. Any wrong entry in the list will be ignored. If this
* property is not defined or contains only wrong classnames, then by default a SecureUberspector is used
* as the only entry in the array.
*
*
* @since 1.5RC1
* @see ChainingUberspector
* @version $Id: a3aaea25b5e99e858970ed11023e74f805d99191 $
* @deprecated since 8.0M1; chaining uberspectors is much more powerful, this class was never more than a proof of
* concept
*/
@Deprecated
public class LinkingUberspector extends UberspectImpl implements Uberspect, RuntimeServicesAware, UberspectLoggable
{
/** The key of the parameter that allows defining the array of uberspectors. */
public static final String UBERSPECT_ARRAY_CLASSNAMES = "runtime.introspector.uberspect.arrayClasses";
/** The runtime is needed for accessing the configuration. */
private RuntimeServices runtime;
/** The array of uberspectors to use. */
private List uberspectors;
@Override
public void setRuntimeServices(RuntimeServices rs)
{
this.runtime = rs;
}
/**
* {@inheritDoc}
*
* This implementation initializes the array of uberspectors.
*
*
* @see org.apache.velocity.util.introspection.Uberspect#init()
*/
@Override
public void init()
{
this.log.debug("Initializing the linking uberspector.");
// Create the array
String[] arrayClassnames = this.runtime.getConfiguration().getStringArray(UBERSPECT_ARRAY_CLASSNAMES);
this.uberspectors = new ArrayList(arrayClassnames.length);
for (String classname : arrayClassnames) {
initializeUberspector(classname);
}
// If the chain is empty, use a SecureUberspector
if (this.uberspectors.isEmpty()) {
this.log.error("No uberspectors defined! "
+ "This uberspector is just a placeholder that relies on at least one real uberspector "
+ "to actually allow method calls. Using SecureUberspector instead as a fallback.");
initializeUberspector(SecureUberspector.class.getCanonicalName());
}
}
/**
* Instantiates and initializes an uberspector class and adds it to the array. Also set the log and runtime
* services, if the class implements the proper interfaces.
*
* @param classname The name of the uberspector class to add to the chain.
*/
protected void initializeUberspector(String classname)
{
// Avoids direct recursive calls
if (!StringUtils.isEmpty(classname) && !classname.equals(this.getClass().getCanonicalName())) {
Uberspect u = instantiateUberspector(classname);
if (u == null) {
return;
}
// Set the log and runtime services, if applicable
if (u instanceof UberspectLoggable) {
((UberspectLoggable) u).setLog(this.log);
}
if (u instanceof RuntimeServicesAware) {
((RuntimeServicesAware) u).setRuntimeServices(this.runtime);
}
// Initialize the uberspector
try {
u.init();
// Add it to the array
this.uberspectors.add(u);
} catch (Exception e) {
this.log.warn(e.getMessage());
// If the initialization failed, don't add this uberspector to the chain.
}
}
}
/**
* Tries to create an uberspector instance using reflection.
*
* @param classname The name of the uberspector class to instantiate.
* @return An instance of the specified Uberspector. If the class cannot be instantiated using the default
* constructor, or does not implement {@link Uberspect}, null is returned.
*/
protected Uberspect instantiateUberspector(String classname)
{
Object o = null;
try {
o = ClassUtils.getNewInstance(classname);
} catch (ClassNotFoundException e) {
this.log.warn(String.format("The specified uberspector [%s]"
+ " does not exist or is not accessible to the current classloader.", classname));
} catch (IllegalAccessException e) {
this.log.warn(String.format("The specified uberspector [%s] does not have a public default constructor.",
classname));
} catch (InstantiationException e) {
this.log.warn(String.format("The specified uberspector [%s] cannot be instantiated.", classname));
} catch (ExceptionInInitializerError e) {
this.log.warn(String.format("Exception while instantiating the Uberspector [%s]: %s", classname, e
.getMessage()));
}
if (!(o instanceof Uberspect)) {
if (o != null) {
this.log.warn("The specified class for Uberspect [" + classname + "] does not implement "
+ Uberspect.class.getName());
}
return null;
}
return (Uberspect) o;
}
@SuppressWarnings("unchecked")
@Override
public Iterator getIterator(Object obj, Info i) throws Exception
{
Iterator it;
for (Uberspect u : this.uberspectors) {
it = u.getIterator(obj, i);
if (it != null) {
return it;
}
}
return null;
}
@Override
public VelMethod getMethod(Object obj, String methodName, Object[] args, Info i) throws Exception
{
VelMethod method;
for (Uberspect u : this.uberspectors) {
method = u.getMethod(obj, methodName, args, i);
if (method != null) {
return method;
}
}
return null;
}
@Override
public VelPropertyGet getPropertyGet(Object obj, String identifier, Info i) throws Exception
{
VelPropertyGet getter;
for (Uberspect u : this.uberspectors) {
getter = u.getPropertyGet(obj, identifier, i);
if (getter != null) {
return getter;
}
}
return null;
}
@Override
public VelPropertySet getPropertySet(Object obj, String identifier, Object arg, Info i) throws Exception
{
VelPropertySet setter;
for (Uberspect u : this.uberspectors) {
setter = u.getPropertySet(obj, identifier, arg, i);
if (setter != null) {
return setter;
}
}
return null;
}
}
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