beanobjectdescription.java

来自「JfreeChart 常用图表例子」· Java 代码 · 共 261 行

/* ========================================================================
 * JCommon : a free general purpose class library for the Java(tm) platform
 * ========================================================================
 *
 * (C) Copyright 2000-2004, by Object Refinery Limited and Contributors.
 * 
 * Project Info:  http://www.jfree.org/jcommon/index.html
 *
 * 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;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
 * in the United States and other countries.]
 * 
 * --------------------------
 * BeanObjectDescription.java
 * --------------------------
 * (C)opyright 2003, 2004, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *
 * $Id: BeanObjectDescription.java,v 1.4 2004/11/29 11:37:30 mungady Exp $
 *
 * Changes (from 19-Feb-2003)
 * -------------------------
 * 19-Feb-2003 : Added standard header and Javadocs (DG);
 * 29-Apr-2003 : Destilled from the JFreeReport project and moved into JCommon
 *
 */

package org.jfree.xml.factory.objects;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Iterator;
import java.util.TreeSet;
import java.util.HashMap;
import java.beans.Introspector;
import java.beans.IntrospectionException;
import java.beans.BeanInfo;
import java.beans.PropertyDescriptor;
import java.io.ObjectInputStream;
import java.io.IOException;

import org.jfree.util.Log;

/**
 * An object-description for a bean object. This object description
 * is very dangerous, if the bean contains properties with undefined
 * types.
 *
 * @author Thomas Morgner
 */
public class BeanObjectDescription extends AbstractObjectDescription {

    private TreeSet ignoredParameters;
    private transient HashMap properties;

    /**
     * Creates a new object description.
     *
     * @param className  the class.
     */
    public BeanObjectDescription(final Class className) {
        this(className, true);
    }

    /**
     * Creates a new object description.
     *
     * @param className  the class.
     * @param init  set to true, to autmaoticly initialise the object description.
     * If set to false, the initialisation is elsewhere.
     */
    public BeanObjectDescription(final Class className, final boolean init) {
        super(className);
        // now create some method descriptions ..
        this.ignoredParameters = new TreeSet();
        readBeanDescription(className, init);
    }

    private boolean isValidMethod (final Method method, final int parCount)
    {
        if (method == null) {
            return false;
        }
        if (!Modifier.isPublic(method.getModifiers())) {
            return false;
        }
        if (Modifier.isStatic(method.getModifiers())) {
            return false;
        }
        if (method.getParameterTypes().length != parCount) {
            return false;
        }
        return true;
    }

    /**
     * Creates an object based on this description.
     *
     * @return The object.
     */
    public Object createObject() {
        try {
            final Object o = getObjectClass().newInstance();
            // now add the various parameters ...

            final Iterator it = getParameterNames();
            while (it.hasNext()) {
                final String name = (String) it.next();

                if (isParameterIgnored(name)) {
                    continue;
                }

                final Method method = findSetMethod(name);
                final Object parameterValue = getParameter(name);
                if (parameterValue == null) {
                    // Log.debug ("Parameter: " + name + " is null");
                }
                else {
                    method.invoke(o, new Object[]{parameterValue});
                }
            }
            return o;
        }
        catch (Exception e) {
            Log.error("Unable to invoke bean method", e);
        }
        return null;
    }

    /**
     * Finds a set method in the bean.
     *
     * @param parameterName  the parameter name.
     *
     * @return The method.
     */
    private Method findSetMethod(final String parameterName) {
        final PropertyDescriptor descriptor 
            = (PropertyDescriptor) this.properties.get(parameterName);
        return descriptor.getWriteMethod();
    }

    /**
     * Finds a get method in the bean.
     *
     * @param parameterName  the paramater name.
     * @return The method.
     */
    private Method findGetMethod(final String parameterName) {
        final PropertyDescriptor descriptor 
            = (PropertyDescriptor) this.properties.get(parameterName);
        return descriptor.getReadMethod();
    }

    /**
     * Sets the parameters in the description to match the supplied object.
     *
     * @param o  the object (<code>null</code> not allowed).
     *
     * @throws ObjectFactoryException if there is a problem.
     */
    public void setParameterFromObject(final Object o)
        throws ObjectFactoryException {
        if (o == null) {
            throw new NullPointerException("Given object is null");
        }
        final Class c = getObjectClass();
        if (!c.isInstance(o)) {
            throw new ObjectFactoryException("Object is no instance of " + c + "(is "
                + o.getClass() + ")");
        }

        final Iterator it = getParameterNames();
        while (it.hasNext()) {
            final String propertyName = (String) it.next();

            if (isParameterIgnored(propertyName)) {
                continue;
            }

            try {
                final Method method = findGetMethod(propertyName);
                final Object retval = method.invoke(o, null);
                if (retval != null) {
                    setParameter(propertyName, retval);
                }
            }
            catch (Exception e) {
                Log.info("Exception on method invokation.", e);
            }

        }
    }

    /**
     * Adds a parameter to the ignored parameters.
     * 
     * @param parameter  the parameter.
     */
    protected void ignoreParameter(final String parameter) {
        this.ignoredParameters.add (parameter);
    }

    /**
     * Returns a flag that indicates whether or not the specified parameter is ignored.
     * 
     * @param parameter  the parameter.
     * 
     * @return The flag.
     */
    protected boolean isParameterIgnored (final String parameter) {
        return this.ignoredParameters.contains(parameter);
    }

  private void readObject(final ObjectInputStream in)
      throws IOException, ClassNotFoundException {
    in.defaultReadObject();
    readBeanDescription(getObjectClass(), false);
  }

  private void readBeanDescription(final Class className, final boolean init) {
    try {
        this.properties = new HashMap();

        final BeanInfo bi = Introspector.getBeanInfo(className);
        final PropertyDescriptor[] propertyDescriptors = bi.getPropertyDescriptors();
        for (int i = 0; i < propertyDescriptors.length; i++)
        {
            final PropertyDescriptor properyDescriptor = propertyDescriptors[i];
            final Method readMethod = properyDescriptor.getReadMethod();
            final Method writeMethod = properyDescriptor.getWriteMethod();
            if (isValidMethod(readMethod, 0) && isValidMethod(writeMethod, 1))
            {
                final String name = properyDescriptor.getName();
                this.properties.put(name, properyDescriptor);
                if (init) {
                    super.setParameterDefinition(name, properyDescriptor.getPropertyType());
                }
            }
        }
    }
    catch (IntrospectionException e) {
        Log.error ("Unable to build bean description", e);
    }
  }
}