FieldAdapterManager.java

/**
 * $Id: FieldAdapterManager.java 54 2009-05-18 15:29:27Z azeckoski $
 * $URL: http://reflectutils.googlecode.com/svn/trunk/src/main/java/org/azeckoski/reflectutils/beanutils/FieldAdapterManager.java $
 * FieldAdapterManager.java - reflectutils - Oct 2, 2008 10:31:44 PM - azeckoski
 **************************************************************************
 * Copyright (c) 2008 Aaron Zeckoski
 * Licensed under the Apache License, Version 2.0
 * 
 * A copy of the Apache License has been included in this 
 * distribution and is available at: http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 * Aaron Zeckoski (azeckoski @ gmail.com) (aaronz @ vt.edu) (aaron @ caret.cam.ac.uk)
 */

package org.azeckoski.reflectutils.beanutils;

import org.azeckoski.reflectutils.ClassLoaderUtils;


/**
 * This manager ensures that the field adapter keeps working even if the class it is adapting goes away
 * 
 * @author Aaron Zeckoski (azeckoski @ gmail.com)
 */
public class FieldAdapterManager {

    public static final String DYNABEAN_CLASSNAME = "org.apache.commons.beanutils.DynaBean";
    public static final String DYNABEAN_ADAPTER = "DynaBeanAdapter";

    protected FieldAdapter fieldAdapter;

    public FieldAdapterManager() {
        /*
         * loads up the field adapter if the right classes exist,
         * this allows us to support DynaBeans even though they may not be available 
         */
        Class<?> dynaBean = ClassLoaderUtils.getClassFromString(DYNABEAN_CLASSNAME);
        if (dynaBean != null) {
            // assumes the adapter impl is in the same path as the interface
            String path = FieldAdapter.class.getName();
            path = path.replace(FieldAdapter.class.getSimpleName(), DYNABEAN_ADAPTER);
            Class<?> adapterClass = ClassLoaderUtils.getClassFromString(path);
            if (adapterClass == null) {
                System.err.println("WARN: Could not find adapter class: " + path + ", will continue without the dynabean adapter");
                //throw new IllegalStateException("Could not find adapter class: " + DYNABEAN_ADAPTER);
            } else {
                // found the adapter class
                try {
                    fieldAdapter = (FieldAdapter) adapterClass.newInstance();
                } catch (Exception e) {
                    System.err.println("WARN: Failed to instantiate field adapter ("+adapterClass+"), will continue without the dynabean adapter: "+e);
                    //throw new RuntimeException("Failed to instantiate field adapter ("+adapterClass+"): "+e, e);
                }
            }
        } else {
            // no dynabean so use default
            fieldAdapter = new DefaultFieldAdapter();
        }
        if (fieldAdapter == null) {
            // failure with dynabean so use default
            fieldAdapter = new DefaultFieldAdapter();
        }
    }

    public FieldAdapter getFieldAdapter() {
        return fieldAdapter;
    }

    public boolean isAdaptableObject(Object obj) {
        boolean adaptable = false;
        try {
            adaptable = fieldAdapter.isAdaptableObject(obj);
        } catch (NoClassDefFoundError e) {
            // invalid field adapter, back to the default one
            fieldAdapter = new DefaultFieldAdapter();
            adaptable = false;
        }
        return adaptable;
    }

    public boolean isAdaptableClass(Class<?> beanClass) {
        boolean adaptable = false;
        try {
            adaptable = fieldAdapter.isAdaptableClass(beanClass);
        } catch (NoClassDefFoundError e) {
            // invalid field adapter, back to the default one
            fieldAdapter = new DefaultFieldAdapter();
            adaptable = false;
        }
        return adaptable;
    }

}