RELEASE_2_1_13/src/java/org/apache/cocoon/components/ExtendedComponentSelector.java - cocoon - Git at Google

 /*
  * 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.cocoon.components;

 import org.apache.avalon.excalibur.component.ExcaliburComponentSelector;
 import org.apache.avalon.excalibur.component.RoleManager;
 import org.apache.avalon.framework.component.Component;
 import org.apache.avalon.framework.component.ComponentException;
 import org.apache.avalon.framework.configuration.Configuration;
 import org.apache.avalon.framework.configuration.ConfigurationException;
 import org.apache.avalon.framework.configuration.DefaultConfiguration;

 /**
  * An extension of <code>ExcaliburComponentSelector</code> that can have a parent
  * and accepts a wider variety of configurations.
  *
  * @author <a href="mailto:sylvain@apache.org">Sylvain Wallez</a>
  * @version CVS $Id$
  */
 public class ExtendedComponentSelector extends ExcaliburComponentSelector
                                        implements ParentAware {

     /** The role manager */
     protected RoleManager roles;

     /** The parent selector, if any */
     protected ExtendedComponentSelector parentSelector;

     /** The parent locator, if any */
     protected ComponentLocator parentLocator;

     /** The class loader to use */
     protected ClassLoader classLoader;

     /** The role of this selector. Set in <code>configure()</code>. */
     protected String roleName;

     /** The default hint */
     protected String defaultHint;

     /** This selector's location (used for debugging purposes) */
     private String location;


     /** Create the ComponentSelector with the Thread context ClassLoader */
     public ExtendedComponentSelector() {
         this.classLoader = Thread.currentThread().getContextClassLoader();
     }

     /** Create the ComponentSelector with a ClassLoader */
     public ExtendedComponentSelector(ClassLoader loader) {
         super(loader);

         if (loader == null) {
             this.classLoader = Thread.currentThread().getContextClassLoader();
         } else {
             this.classLoader = loader;
         }
     }

     /**
      * Get the name for component-instance elements (i.e. components not defined
      * by their role shortcut. If <code>null</code>, any element having a 'class'
      * attribute will be considered as a component instance.
      * <p>
      * The default here is to return <code>null</code>, and subclasses can redefine
      * this method to return particular values.
      *
      * @return <code>null</code>, but can be changed by subclasses
      */
     protected String getComponentInstanceName() {
         return null;
     }

     /**
      * Get the name of the attribute giving the class name of a component.
      * The default here is "class", but this can be overriden in subclasses.
      *
      * @return "<code>class</code>", but can be changed by subclasses
      */
     protected String getClassAttributeName() {
         return "class";
     }

     /**
      * Get the name of the attribute giving the default hint to use if
      * none is given. The default here is "default", but this can be
      * overriden in subclasses. If this method returns <code>null</code>,
      * no default hint can be specified.
      *
      * @return "<code>default</code>", but can be changed by subclasses
      */
     protected String getDefaultHintAttributeName() {
         return "default";
     }

     /**
      * Configure the RoleManager. Redeclared only because parent member is private.
      */
     public void setRoleManager(RoleManager roles) {
         super.setRoleManager(roles);
         this.roles = roles;
     }

     /**
      * Set the parent of this selector. This can be done after the selector is
      * initialized, but <em>only once</em>. This allows this selector to be
      * created by a component manager while still being able to have a parent.
      *
      * @param parent the parent selector
      * @throws IllegalStateException if parent is already set
      */
 /*    public void setParentSelector(ComponentSelector parent) {
         if (this.parentSelector != null) {
             throw new IllegalStateException("Parent selector is already set");
         }
         this.parentSelector = parent;
         this.parentComponents = new HashSet();
     }
 */

     /**
      * Get the role name for this selector. This is called by <code>configure()</code>
      * to set the value of <code>this.roleName</code>.
      *
      * @return the role name, or <code>null<code> if it couldn't be determined.
      */
     protected String getRoleName(Configuration config) {
         // Get the role for this selector
         String roleName = config.getAttribute("role", null);
         if (roleName == null && this.roles != null) {
             roleName = this.roles.getRoleForName(config.getName());
         }

         return roleName;
     }

     /**
      * Configure this selector. This is the main difference with the parent class :
      * <ul>
      * <li>if {@link #getComponentInstanceName()} returns <code>null</code>,
      *     any child configurations having a attribute named as the result of
      *     {@link #getClassAttributeName()}, is considered as a component instance.
      * </li>
      * <li>if {@link #getComponentInstanceName()} returns a non-null value,
      *     only child configurations having this name are considered as a
      *     component instance.
      * </li>
      * <li>if other cases, it's name is considered to be a hint in the role manager.
      *     The behaviour is then the same as <code>ExcaliburComponentSelector</code>.
      * </li>
      *
      * @param config the configuration
      * @throws ConfigurationException if some hints aren't defined
      */
     public void configure(Configuration config) throws ConfigurationException {

         // Store location
         this.location = config.getLocation();

         this.roleName = getRoleName(config);

         // Pass a copy of the top-level object to superclass so that
         // our name is properly initialized
         // FIXME : could be avoided if parent m_role was protected or had protected accessors
         DefaultConfiguration temp = new DefaultConfiguration(config.getName(), this.location);
         if (config.getAttribute("role", null) != null) {
             temp.setAttribute("role", this.roleName);
         }
         super.configure(temp);

         // Get default hint
         this.defaultHint = config.getAttribute(this.getDefaultHintAttributeName(), null);

         // Add components
         String compInstanceName = getComponentInstanceName();

         Configuration[] instances = config.getChildren();

         for (int i = 0; i < instances.length; i++) {
             Configuration instance = instances[i];

             Object hint = instance.getAttribute("name").trim();

             String classAttr = instance.getAttribute(getClassAttributeName(), null);
             String className;

             if (compInstanceName == null) {
                 // component-instance implicitly defined by the presence of the 'class' attribute
                 if (classAttr == null) {
                     className = this.roles.getDefaultClassNameForHint(roleName, instance.getName());
                 } else {
                     className = classAttr.trim();
                 }

             } else {
                 // component-instances names explicitly defined
                 if (compInstanceName.equals(instance.getName())) {
                     className = (classAttr == null) ? null : classAttr.trim();
                 } else {
                     className = this.roles.getDefaultClassNameForHint(roleName, instance.getName());
                 }
             }

             if (className == null) {
                 String message = "Unable to determine class name for component named '" + hint +
                     "' at " + instance.getLocation();

                 getLogger().error(message);
                 throw new ConfigurationException(message);
             }

             try {
                 Class clazz = this.classLoader.loadClass(className);
                 addComponent(hint, clazz, instance);

             } catch (Exception e) {
                 String message = "Could not load class " + className + " for component named '" +
                                  hint + "' at " + instance.getLocation();

                 getLogger().error(message, e);
                 throw new ConfigurationException(message, e);
             }
         }
     }

     /**
      * Get the default hint, if any for this selector.
      */
     public String getDefaultHint() {
         // Inherit parent default hint if have no own
         if (this.defaultHint == null && this.parentSelector != null) {
             return this.parentSelector.getDefaultHint();
         }

         return this.defaultHint;
     }

     /* (non-Javadoc)
      * @see org.apache.avalon.framework.component.ComponentSelector#select(java.lang.Object)
      */
     public Component select(Object hint) throws ComponentException {
         if (hint == null) {
             hint = this.defaultHint;
         }

         if (parentSelector == null) {
             // No parent: default behaviour
             return super.select(hint);
         }

         try {
             // Try in this selector first
             final Component component = super.select(hint);
             return component;

         } catch (ComponentException original) {
             try {
                 // Doesn't exist here: try in parent selector
                 final Component component = this.parentSelector.select(hint);
                 return component;

             } catch (ComponentException nested) {
                 // Doesn't exist in parent too: throw exception.

                 if (nested.getCause() != null) {
                     // Nested exception has a cause; let's throw it instead of original.
                     throw nested;
                 }

                 // Throw original exception
                 throw original;
             }
         }
     }

     /* (non-Javadoc)
      * @see org.apache.avalon.framework.component.ComponentSelector#release(org.apache.avalon.framework.component.Component)
      */
     public void release(Component component) {
         // Was it selected on the parent ?
         if (this.parentSelector != null && this.parentSelector.canRelease(component)) {
             // Yes
             this.parentSelector.release(component);
         } else {
             // No
             super.release(component);
         }
     }

     /**
      * Does this selector or its parent have the given hint ?
      */
     public boolean hasComponent(Object hint) {
         boolean exists = super.hasComponent(hint);
         if (!exists && this.parentSelector != null) {
             exists = this.parentSelector.hasComponent(hint);
         }
         return exists;
     }

     /**
      * Does this selector declare a given hint? Check is performed on the components declared for this
      * selector only, and <strong>not</strong> those potentially inherited from the parent selector.
      *
      * @param hint the hint to check for
      * @return <code>true</code> if this selector has the specified hint
      */
     protected boolean hasDeclaredComponent(Object hint) {
         return super.hasComponent(hint);
     }

     /* (non-Javadoc)
      * @see org.apache.cocoon.components.ParentAware#setParentInformation(org.apache.avalon.framework.component.ComponentManager, java.lang.String)
      */
     public void setParentLocator(ComponentLocator locator)
     throws ComponentException {
         if (this.parentSelector != null) {
             throw new ComponentException(null, "Parent selector is already set");
         }
         this.parentLocator = locator;
         this.parentSelector = (ExtendedComponentSelector) locator.lookup();
     }

     /* (non-Javadoc)
      * @see org.apache.avalon.framework.activity.Disposable#dispose()
      */
     public void dispose() {
         super.dispose();
         if (this.parentLocator != null) {
             this.parentLocator.release(this.parentSelector);
             this.parentLocator = null;
             this.parentSelector = null;
         }
     }

     /* (non-Javadoc)
      * @see org.apache.avalon.excalibur.component.ExcaliburComponentSelector#canRelease(org.apache.avalon.framework.component.Component)
      */
     protected boolean canRelease(Component component) {
         if (this.parentSelector != null && this.parentSelector.canRelease(component)) {
             return true;
         }

         return super.canRelease(component);
     }
 }
	/*
	* 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.cocoon.components;

	import org.apache.avalon.excalibur.component.ExcaliburComponentSelector;
	import org.apache.avalon.excalibur.component.RoleManager;
	import org.apache.avalon.framework.component.Component;
	import org.apache.avalon.framework.component.ComponentException;
	import org.apache.avalon.framework.configuration.Configuration;
	import org.apache.avalon.framework.configuration.ConfigurationException;
	import org.apache.avalon.framework.configuration.DefaultConfiguration;

	/**
	* An extension of <code>ExcaliburComponentSelector</code> that can have a parent
	* and accepts a wider variety of configurations.
	*
	* @author <a href="mailto:sylvain@apache.org">Sylvain Wallez</a>
	* @version CVS $Id$
	*/
	public class ExtendedComponentSelector extends ExcaliburComponentSelector
	implements ParentAware {

	/** The role manager */
	protected RoleManager roles;

	/** The parent selector, if any */
	protected ExtendedComponentSelector parentSelector;

	/** The parent locator, if any */
	protected ComponentLocator parentLocator;

	/** The class loader to use */
	protected ClassLoader classLoader;

	/** The role of this selector. Set in <code>configure()</code>. */
	protected String roleName;

	/** The default hint */
	protected String defaultHint;

	/** This selector's location (used for debugging purposes) */
	private String location;


	/** Create the ComponentSelector with the Thread context ClassLoader */
	public ExtendedComponentSelector() {
	this.classLoader = Thread.currentThread().getContextClassLoader();
	}

	/** Create the ComponentSelector with a ClassLoader */
	public ExtendedComponentSelector(ClassLoader loader) {
	super(loader);

	if (loader == null) {
	this.classLoader = Thread.currentThread().getContextClassLoader();
	} else {
	this.classLoader = loader;
	}
	}

	/**
	* Get the name for component-instance elements (i.e. components not defined
	* by their role shortcut. If <code>null</code>, any element having a 'class'
	* attribute will be considered as a component instance.
	* <p>
	* The default here is to return <code>null</code>, and subclasses can redefine
	* this method to return particular values.
	*
	* @return <code>null</code>, but can be changed by subclasses
	*/
	protected String getComponentInstanceName() {
	return null;
	}

	/**
	* Get the name of the attribute giving the class name of a component.
	* The default here is "class", but this can be overriden in subclasses.
	*
	* @return "<code>class</code>", but can be changed by subclasses
	*/
	protected String getClassAttributeName() {
	return "class";
	}

	/**
	* Get the name of the attribute giving the default hint to use if
	* none is given. The default here is "default", but this can be
	* overriden in subclasses. If this method returns <code>null</code>,
	* no default hint can be specified.
	*
	* @return "<code>default</code>", but can be changed by subclasses
	*/
	protected String getDefaultHintAttributeName() {
	return "default";
	}

	/**
	* Configure the RoleManager. Redeclared only because parent member is private.
	*/
	public void setRoleManager(RoleManager roles) {
	super.setRoleManager(roles);
	this.roles = roles;
	}

	/**
	* Set the parent of this selector. This can be done after the selector is
	* initialized, but <em>only once</em>. This allows this selector to be
	* created by a component manager while still being able to have a parent.
	*
	* @param parent the parent selector
	* @throws IllegalStateException if parent is already set
	*/
	/* public void setParentSelector(ComponentSelector parent) {
	if (this.parentSelector != null) {
	throw new IllegalStateException("Parent selector is already set");
	}
	this.parentSelector = parent;
	this.parentComponents = new HashSet();
	}
	*/

	/**
	* Get the role name for this selector. This is called by <code>configure()</code>
	* to set the value of <code>this.roleName</code>.
	*
	* @return the role name, or <code>null<code> if it couldn't be determined.
	*/
	protected String getRoleName(Configuration config) {
	// Get the role for this selector
	String roleName = config.getAttribute("role", null);
	if (roleName == null && this.roles != null) {
	roleName = this.roles.getRoleForName(config.getName());
	}

	return roleName;
	}

	/**
	* Configure this selector. This is the main difference with the parent class :
	* <ul>
	* <li>if {@link #getComponentInstanceName()} returns <code>null</code>,
	* any child configurations having a attribute named as the result of
	* {@link #getClassAttributeName()}, is considered as a component instance.
	* </li>
	* <li>if {@link #getComponentInstanceName()} returns a non-null value,
	* only child configurations having this name are considered as a
	* component instance.
	* </li>
	* <li>if other cases, it's name is considered to be a hint in the role manager.
	* The behaviour is then the same as <code>ExcaliburComponentSelector</code>.
	* </li>
	*
	* @param config the configuration
	* @throws ConfigurationException if some hints aren't defined
	*/
	public void configure(Configuration config) throws ConfigurationException {

	// Store location
	this.location = config.getLocation();

	this.roleName = getRoleName(config);

	// Pass a copy of the top-level object to superclass so that
	// our name is properly initialized
	// FIXME : could be avoided if parent m_role was protected or had protected accessors
	DefaultConfiguration temp = new DefaultConfiguration(config.getName(), this.location);
	if (config.getAttribute("role", null) != null) {
	temp.setAttribute("role", this.roleName);
	}
	super.configure(temp);

	// Get default hint
	this.defaultHint = config.getAttribute(this.getDefaultHintAttributeName(), null);

	// Add components
	String compInstanceName = getComponentInstanceName();

	Configuration[] instances = config.getChildren();

	for (int i = 0; i < instances.length; i++) {
	Configuration instance = instances[i];

	Object hint = instance.getAttribute("name").trim();

	String classAttr = instance.getAttribute(getClassAttributeName(), null);
	String className;

	if (compInstanceName == null) {
	// component-instance implicitly defined by the presence of the 'class' attribute
	if (classAttr == null) {
	className = this.roles.getDefaultClassNameForHint(roleName, instance.getName());
	} else {
	className = classAttr.trim();
	}

	} else {
	// component-instances names explicitly defined
	if (compInstanceName.equals(instance.getName())) {
	className = (classAttr == null) ? null : classAttr.trim();
	} else {
	className = this.roles.getDefaultClassNameForHint(roleName, instance.getName());
	}
	}

	if (className == null) {
	String message = "Unable to determine class name for component named '" + hint +
	"' at " + instance.getLocation();

	getLogger().error(message);
	throw new ConfigurationException(message);
	}

	try {
	Class clazz = this.classLoader.loadClass(className);
	addComponent(hint, clazz, instance);

	} catch (Exception e) {
	String message = "Could not load class " + className + " for component named '" +
	hint + "' at " + instance.getLocation();

	getLogger().error(message, e);
	throw new ConfigurationException(message, e);
	}
	}
	}

	/**
	* Get the default hint, if any for this selector.
	*/
	public String getDefaultHint() {
	// Inherit parent default hint if have no own
	if (this.defaultHint == null && this.parentSelector != null) {
	return this.parentSelector.getDefaultHint();
	}

	return this.defaultHint;
	}

	/* (non-Javadoc)
	* @see org.apache.avalon.framework.component.ComponentSelector#select(java.lang.Object)
	*/
	public Component select(Object hint) throws ComponentException {
	if (hint == null) {
	hint = this.defaultHint;
	}

	if (parentSelector == null) {
	// No parent: default behaviour
	return super.select(hint);
	}

	try {
	// Try in this selector first
	final Component component = super.select(hint);
	return component;

	} catch (ComponentException original) {
	try {
	// Doesn't exist here: try in parent selector
	final Component component = this.parentSelector.select(hint);
	return component;

	} catch (ComponentException nested) {
	// Doesn't exist in parent too: throw exception.

	if (nested.getCause() != null) {
	// Nested exception has a cause; let's throw it instead of original.
	throw nested;
	}

	// Throw original exception
	throw original;
	}
	}
	}

	/* (non-Javadoc)
	* @see org.apache.avalon.framework.component.ComponentSelector#release(org.apache.avalon.framework.component.Component)
	*/
	public void release(Component component) {
	// Was it selected on the parent ?
	if (this.parentSelector != null && this.parentSelector.canRelease(component)) {
	// Yes
	this.parentSelector.release(component);
	} else {
	// No
	super.release(component);
	}
	}

	/**
	* Does this selector or its parent have the given hint ?
	*/
	public boolean hasComponent(Object hint) {
	boolean exists = super.hasComponent(hint);
	if (!exists && this.parentSelector != null) {
	exists = this.parentSelector.hasComponent(hint);
	}
	return exists;
	}

	/**
	* Does this selector declare a given hint? Check is performed on the components declared for this
	* selector only, and <strong>not</strong> those potentially inherited from the parent selector.
	*
	* @param hint the hint to check for
	* @return <code>true</code> if this selector has the specified hint
	*/
	protected boolean hasDeclaredComponent(Object hint) {
	return super.hasComponent(hint);
	}

	/* (non-Javadoc)
	* @see org.apache.cocoon.components.ParentAware#setParentInformation(org.apache.avalon.framework.component.ComponentManager, java.lang.String)
	*/
	public void setParentLocator(ComponentLocator locator)
	throws ComponentException {
	if (this.parentSelector != null) {
	throw new ComponentException(null, "Parent selector is already set");
	}
	this.parentLocator = locator;
	this.parentSelector = (ExtendedComponentSelector) locator.lookup();
	}

	/* (non-Javadoc)
	* @see org.apache.avalon.framework.activity.Disposable#dispose()
	*/
	public void dispose() {
	super.dispose();
	if (this.parentLocator != null) {
	this.parentLocator.release(this.parentSelector);
	this.parentLocator = null;
	this.parentSelector = null;
	}
	}

	/* (non-Javadoc)
	* @see org.apache.avalon.excalibur.component.ExcaliburComponentSelector#canRelease(org.apache.avalon.framework.component.Component)
	*/
	protected boolean canRelease(Component component) {
	if (this.parentSelector != null && this.parentSelector.canRelease(component)) {
	return true;
	}

	return super.canRelease(component);
	}
	}