AspectContext.java

/**************************************************************************************
 * Copyright (c) Jonas Bon�r, Alexandre Vasseur. All rights reserved.                 *
 * http://aspectwerkz.codehaus.org                                                    *
 * ---------------------------------------------------------------------------------- *
 * The software in this package is published under the terms of the LGPL license      *
 * a copy of which has been included with this distribution in the license.txt file.  *
 **************************************************************************************/
package org.codehaus.aspectwerkz;

import org.codehaus.aspectwerkz.definition.AspectDefinition;

import java.io.ObjectInputStream;
import java.io.Serializable;
import java.lang.ref.WeakReference;
import java.util.HashMap;
import java.util.Map;

/**
 * Contains information about and for classes that has been defined as cross-cutting.
 * <p/>
 * FIXME why serializable ?
 *
 * @author <a href="mailto:jboner@codehaus.org">Jonas Bon�r </a>
 */
public final class AspectContext implements Serializable {
    /**
     * An empty <code>Object</code> array.
     */
    public static final Object[] EMPTY_OBJECT_ARRAY = new Object[]{};

    /**
     * The name for the cross-cuttable class.
     */
    private String m_name;

    /**
     * The qualified name of the aspect. Stored for serialization purpose.
     */
    private String m_qName;

    /**
     * The aspect class, wrapped in a weak reference since is a key of aspect container referenced by this object.
     */
    private transient WeakReference m_aspectClassRef;

    /**
     * Holds the deployment model.
     */
    private DeploymentModel m_deploymentModel;

    /**
     * Holds the parameters passed to the aspect.
     */
    private Map m_parameters = new HashMap();

    /**
     * Holds the metadata.
     */
    private Map m_metaData = new HashMap();

    /**
     * The UUID for the system.
     */
    private String m_uuid;

    /**
     * The aspect definition.
     */
    private transient AspectDefinition m_aspectDefinition;

    /**
     * The associated object. Null for perJVM, class, target or this instance or thread for other deployment models.
     */
    private transient Object m_associatedObject;

    /**
     * Creates a new cross-cutting info instance.
     *
     * @param uuid
     * @param aspectClass
     * @param deploymentModel
     * @param aspectDef
     * @param parameters
     * @param associated instance (null/class/instance/thread)
     */
    public AspectContext(final String uuid,
                         final Class aspectClass,
                         final String name,
                         final DeploymentModel deploymentModel,
                         final AspectDefinition aspectDef,
                         final Map parameters,
                         final Object associated) {
        m_uuid = uuid;
        m_aspectClassRef = new WeakReference(aspectClass);
        m_name = name;
        m_qName = aspectDef.getQualifiedName();
        m_deploymentModel = deploymentModel;
        m_aspectDefinition = aspectDef;
        if (parameters != null) {
            m_parameters = parameters;
        }
        m_associatedObject = associated;
    }

    /**
     * Returns the UUID for the system.
     *
     * @return the UUID for the system
     */
    public String getUuid() {
        return m_uuid;
    }

    /**
     * Returns the name of the aspect.
     *
     * @return the name of the aspect
     */
    public String getName() {
        return m_name;
    }

    /**
     * Returns the deployment model.
     *
     * @return the deployment model
     */
    public DeploymentModel getDeploymentModel() {
        return m_deploymentModel;
    }

    /**
     * Returns the cross-cuttable class.
     *
     * @return the cross-cuttable class
     */
    public Class getAspectClass() {
        return (Class) m_aspectClassRef.get();
    }

    /**
     * Returns the aspect definition.
     * <p/>
     * Will return null after deserialization.
     *
     * @return the aspect definition
     */
    public AspectDefinition getAspectDefinition() {
        return m_aspectDefinition;
    }

    /**
     * Sets a parameter.
     *
     * @param name  the name of the parameter
     * @param value the value of the parameter
     */
    public void setParameter(final String name, final String value) {
        m_parameters.put(name, value);
    }

    /**
     * Returns the value of a parameter.
     *
     * @param name the name of the parameter
     * @return the value of the parameter or null if not specified
     */
    public String getParameter(final String name) {
        return (String) m_parameters.get(name);
    }

    /**
     * Adds metadata.
     *
     * @param key   the key
     * @param value the value
     */
    public void addMetaData(final Object key, final Object value) {
        m_metaData.put(key, value);
    }

    /**
     * Returns the metadata for a specific key.
     *
     * @param key the key
     * @return the value
     */
    public Object getMetaData(final Object key) {
        return m_metaData.get(key);
    }

    /**
     * Provides custom deserialization.
     *
     * @param stream the object input stream containing the serialized object
     * @throws Exception in case of failure
     */
    private void readObject(final ObjectInputStream stream) throws Exception {
        ObjectInputStream.GetField fields = stream.readFields();
        m_uuid = (String) fields.get("m_uuid", null);
        m_name = (String) fields.get("m_name", null);
        m_qName = (String) fields.get("m_qName", null);
        Class aspectClass = Class.forName(m_name);
        m_aspectClassRef = new WeakReference(aspectClass);
        m_deploymentModel = (DeploymentModel) fields.get("m_deploymentModel", DeploymentModel.PER_JVM);
        m_parameters = (Map) fields.get("m_parameters", new HashMap());
        m_metaData = (Map) fields.get("m_metaData", new HashMap());

        //TODO aspectDef from m_qName
    }

    /**
     * Returns the associated object with the aspect beeing instantiated. This depend on the aspect deployment model.
     * It can be a null/class/instance/thread.
     *
     * @return
     */
    public Object getAssociatedObject() {
        return m_associatedObject;
    }
}