metadata.java

java实现浏览器等本地桌面的功能

/*
 * $Id: MetaData.java,v 1.3 2005/10/10 17:01:09 rbair Exp $
 *
 * Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

package org.jdesktop.binding.metadata;

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

/**
 * <p>
 * Class for representing the meta-data for an field in a data model.
 * A &quot;field&quot; may map to a column on a RowSet, a property on a JavaBean,
 * or some other discrete data element on a data model.
 * The meta-data describes aspects of a data field such as it's name,
 * type, and edit constraints.  This class may be used when such information
 * isn't encapsulated in the data model object itself and thus must be represented
 * in an external object.  Meta-data is intended only for holding state about
 * a data model element and is not intended for implementing application semantics.</p>
 * <p>
 * A meta-data object should be initialized at a minimum with a name, class,
 * and label.  Additional meta-data properties can be set as necessary.
 * For example:<br>
 * <pre><code>
 *     MetaData metaData = new MetaData(&quot;firstname&quot;, String.class,
 *                                      &quot;First Name&quot;);
 *     metaData.setRequired(true);
 * </code></pre>
 * If the associated data model field requires application-specific validation
 * logic to verify the correctness of a potential value, one or more Validator
 * instances can be added to the meta-data object.  Example:<br>
 * <pre><code>
 *     MetaData metaData = new MetaData(&quot;creditcard&quot;, String.class,
 *                                      &quot;Credit Card Number&quot;
 *     metaData.setRequired(true);
 *     metaData.addValidator(new MyCreditCardValidator());
 * </code></pre>
 * </p>
 *
 * @author Amy Fowler
 * @author Rich Bair
 * @version 1.0
 */

public class MetaData {
    protected String name;
    protected Class klass = String.class;
    protected String label;
    protected Converter converter = null;
    protected Object decodeFormat = null;
    protected Object encodeFormat = null;
    protected boolean readOnly = false;
    protected int minValueCount = 0; // null value okay
    protected int maxValueCount = 1; // only one value allowed
    protected int displayWidth = 24;
    protected ArrayList validators = null;

    protected Map customProps = new HashMap();
    protected PropertyChangeSupport pcs;

    /**
     * Instantiates a meta-data object with a default name &quot;value&quot; and
     * a default field class equal to <code>java.lang.String</code>.
     * This provides the no-argument constructor required for JavaBeans.
     * It is recommended that the program explicitly set a meaningful
     * &quot;name&quot; property.
     */
    public MetaData() {
        this("value");
    }

    /**
     * Instantiates a meta-data object with the specified name and
     * a default field class equal to <code>java.lang.String</code>.
     * @param name String containing the name of the data field
     */
    public MetaData(String name) {
        this.name = name;
    }

    /**
     * Instantiates a meta-data object with the specified name and
     * field class.
     * @param name String containing the name of the data field
     * @param klass Class indicating type of data field
     */
    public MetaData(String name, Class klass) {
        this(name);
        this.klass = klass;
    }

    /**
     * Instantiates a meta-data object with the specified name,
     * field class, and label.
     * @param name String containing the name of the data field
     * @param klass Class indicating type of data field
     * @param label String containing the user-displayable label for the
     *        data field
     */
    public MetaData(String name, Class klass, String label) {
        this(name, klass);
        this.label = label;
    }

    /**
     * Gets the meta-data &quot;name&quot; property which indicates
     * the logical name of the associated data field.
     * @see #setName
     * @return String containing the name of the data field.
     */
    public String getName() {
        return name;
    }

    /**
     * Sets the meta-data &quot;name&quot; property.
     * @see #getName
     * @param name String containing the name of the data field
     */
    public void setName(String name) {
        String oldName = this.name;
        this.name = name;
        firePropertyChange("name", oldName, name);
    }

    /**
     * Gets the meta-data's &quot;elementClass&quot; property which
     * indicates the type of the associated data field.
     * The default field class is <code>java.lang.String</code>.
     * @see #setElementClass
     * @return Class indicating type of data field
     */
    public Class getElementClass() {
        return klass;
    }

    /**
     * Sets the meta-data's &quot;elementClass&quot; property.
     * This <code>set</code> method is provided for meta-data bean initialization
     * only; the field class is not intended to be modified after initialization,
     * since other aspects of a meta-data object may depend on this type setting.
     * @see #getElementClass
     * @param klass Class indicating type of data field
     */
    public void setElementClass(Class klass) {
        Class oldClass = this.klass;
        this.klass = klass;
        firePropertyChange("elementClass", oldClass, klass);
    }

    /**
     * Gets the meta-data's &quot;label&quot; property, which provides
     * a label for the associated data field.  The label is intended
     * for display to the end-user and may be localized.
     * If no label has been explicitly set, then the meta-data's name is
     * returned.
     * @see #setLabel
     * @return String containing the user-displayable label for the
     *         data field
     */
    public String getLabel() {
        return label == null? name : label;
    }

    /**
     * Sets the meta-data's &quot;label&quot; property.
     * @todo Rename to setTitle
     *
     * @see #getLabel
     * @param label String containing the user-displable label for the
     *        data field
     */
    public void setLabel(String label) {
        String oldLabel = this.label;
        this.label = label;
        firePropertyChange("label", oldLabel, label);
    }

    /**
     * Gets the meta-data's converter, which performs conversions between
     * string values and objects of the associated data field's type.
     * If no converter was explicitly set on this meta-data object,
     * this method will retrieve a default converter for this data
     * field's type from the converter registry.  If no default converter
     * is registered, this method will return <code>null</code>.
     * @see Converters#get
     * @see #setConverter
     * @see #getElementClass
     * @return Converter used to perform conversions between string values
     *         and objects of this field's type
     */
    public Converter getConverter() {
        if (converter == null) {
            return Converters.get(klass);
        }
        return converter;
    }

    /**
     * Sets the meta-data's converter.
     *
     * @see #getConverter
     * @param converter Converter used to perform conversions between string values
     *         and objects of this field's type
     */
    public void setConverter(Converter converter) {
        Converter oldConverter = this.converter;
        this.converter = converter;
        firePropertyChange("converter", oldConverter, converter);
    }

    /**
     * Gets the meta-data's decode format which is used when converting
     * values from a string representation.  This property must be used when
     * conversion requires format information on how the string representation
     * is structured.  For example, a decode format should be used when decoding
     * date values.  The default decode format is <code>null</code>.
     * @see #setDecodeFormat
     * @return format object used to describe format for string-to-object conversion
     */
    public Object getDecodeFormat() {
        return decodeFormat;
    }

    /**
     * Sets the meta-data's decode format which is used when converting
     * values from a string representation.
     * @see #getDecodeFormat
     * @see java.text.DateFormat
     * @param format object used to describe format for string-to-object conversion
     */
    public void setDecodeFormat(Object format) {
        Object oldDecodeFormat = this.decodeFormat;
        this.decodeFormat = format;
        firePropertyChange("decodeFormat", oldDecodeFormat, format);
    }

    /**
     * Gets the meta-data's encode format which is used when converting
     * values to a string representation.  This property must be used when
     * conversion requires format information on how the string representation
     * should be generated.  For example, an encode format should be used when
     * encoding date values.  The default encode format is <code>null</code>.
     * @see #setEncodeFormat
     * @return format object used to describe format for object-to-string conversion
     */
    public Object getEncodeFormat() {
        return encodeFormat;
    }

    /**
     * Sets the meta-data's encode format which is used when converting
     * values to a string representation.
     * @see #getEncodeFormat
     * @see java.text.DateFormat
     * @param format object used to describe format for object-to-string conversion
     */
    public void setEncodeFormat(Object format) {
        Object oldEncodeFormat = this.encodeFormat;
        this.encodeFormat = format;
        firePropertyChange("encodeFormat", oldEncodeFormat, format);
    }

    /**
     * @return integer containing the number of characters required to
     *        display the value
     */
    public int getDisplayWidth() {
        return displayWidth;