optionscollectiontag.java

这是一个轻便的j2ee的web应用框架,是一个在多个项目中运用的实际框架,采用struts,hebinate,xml等技术,有丰富的tag,role,navigation,session,dictio

/*
 * $Header: /sfroot/cvs/esimple/src/core/com/esimple/framework/web/taglib/html/OptionsCollectionTag.java,v 1.1.1.1 2004/09/08 06:38:18 lava Exp $
 * $Revision: 1.1.1.1 $
 * $Date: 2004/09/08 06:38:18 $
 * 
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Struts", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package com.esimple.framework.web.taglib.html;

import java.lang.reflect.InvocationTargetException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;

import org.apache.commons.beanutils.PropertyUtils;
import org.apache.commons.collections.IteratorUtils;
import org.apache.struts.util.MessageResources;
import org.apache.struts.util.RequestUtils;
import org.apache.struts.util.ResponseUtils;

/**
 * Tag for creating multiple &lt;select&gt; options from a collection. The
 * collection may be part of the enclosing form, or may be independent of
 * the form. Each element of the collection must expose a 'label' and a
 * 'value', the property names of which are configurable by attributes of
 * this tag.
 * <p>
 * The collection may be an array of objects, a Collection, an Enumeration,
 * an Iterator, or a Map.
 * <p>
 * <b>NOTE</b> - This tag requires a Java2 (JDK 1.2 or later) platform.
 *
 * @author Martin Cooper
 * @version $Revision: 1.1.1.1 $ $Date: 2004/09/08 06:38:18 $
 * @since Struts 1.1
 */

public class OptionsCollectionTag extends TagSupport {

    // ----------------------------------------------------- Instance Variables

    /**
     * The message resources for this package.
     */
    protected static MessageResources messages =
        MessageResources.getMessageResources(Constants.Package + ".LocalStrings");

    // ------------------------------------------------------------- Properties

    /**
     * Should the label values be filtered for HTML sensitive characters?
     */
    protected boolean filter = true;

    public boolean getFilter() {
        return filter;
    }

    public void setFilter(boolean filter) {
        this.filter = filter;
    }

    /**
     * The name of the bean property containing the label.
     */
    protected String label = "label";

    public String getLabel() {
        return label;
    }

    public void setLabel(String label) {
        this.label = label;
    }

    /**
     * The name of the bean containing the values collection.
     */
    protected String name = Constants.BEAN_KEY;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    /**
     * The name of the property to use to build the values collection.
     */
    protected String property = null;

    public String getProperty() {
        return property;
    }

    public void setProperty(String property) {
        this.property = property;
    }

    /**
     * The style associated with this tag.
     */
    private String style = null;

    public String getStyle() {
        return style;
    }

    public void setStyle(String style) {
        this.style = style;
    }

    /**
     * The named style class associated with this tag.
     */
    private String styleClass = null;

    public String getStyleClass() {
        return styleClass;
    }

    public void setStyleClass(String styleClass) {
        this.styleClass = styleClass;
    }

    /**
     * The name of the bean property containing the value.
     */
    protected String value = "value";

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }

    // --------------------------------------------------------- Public Methods

    /**
     * Process the start of this tag.
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doStartTag() throws JspException {

        // Acquire the select tag we are associated with
        SelectTag selectTag = (SelectTag) pageContext.getAttribute(Constants.SELECT_KEY);

        if (selectTag == null) {
            JspException e = new JspException(messages.getMessage("optionsCollectionTag.select"));
            RequestUtils.saveException(pageContext, e);
            throw e;
        }

        // Acquire the collection containing our options
        Object collection = RequestUtils.lookup(pageContext, name, property, null);

        if (collection == null) {
            JspException e =
                new JspException(messages.getMessage("optionsCollectionTag.collection"));
            RequestUtils.saveException(pageContext, e);
            throw e;
        }

        // Acquire an iterator over the options collection
        Iterator iter = getIterator(collection);

        StringBuffer sb = new StringBuffer();

        // Render the options
        while (iter.hasNext()) {

            Object bean = iter.next();
            Object beanLabel = null;
            Object beanValue = null;

            // Get the label for this option
            try {
                beanLabel = PropertyUtils.getProperty(bean, label);
                if (beanLabel == null) {
                    beanLabel = "";
                }
            } catch (IllegalAccessException e) {
                JspException jspe =
                    new JspException(messages.getMessage("getter.access", label, bean));
                RequestUtils.saveException(pageContext, jspe);
                throw jspe;
            } catch (InvocationTargetException e) {
                Throwable t = e.getTargetException();
                JspException jspe =
                    new JspException(messages.getMessage("getter.result", label, t.toString()));
                RequestUtils.saveException(pageContext, jspe);
                throw jspe;
            } catch (NoSuchMethodException e) {
                JspException jspe =
                    new JspException(messages.getMessage("getter.method", label, bean));
                RequestUtils.saveException(pageContext, jspe);
                throw jspe;
            }

            // Get the value for this option
            try {
                beanValue = PropertyUtils.getProperty(bean, value);
                if (beanValue == null) {
                    beanValue = "";
                }
            } catch (IllegalAccessException e) {
                JspException jspe =
                    new JspException(messages.getMessage("getter.access", value, bean));
                RequestUtils.saveException(pageContext, jspe);
                throw jspe;
            } catch (InvocationTargetException e) {
                Throwable t = e.getTargetException();
                JspException jspe =
                    new JspException(messages.getMessage("getter.result", value, t.toString()));
                RequestUtils.saveException(pageContext, jspe);
                throw jspe;
            } catch (NoSuchMethodException e) {
                JspException jspe =
                    new JspException(messages.getMessage("getter.method", value, bean));
                RequestUtils.saveException(pageContext, jspe);
                throw jspe;
            }

            String stringLabel = beanLabel.toString();
            String stringValue = beanValue.toString();

            // Render this option
            addOption(sb, stringLabel, stringValue, selectTag.isMatched(stringValue));
        }

        // Render this element to our writer
        ResponseUtils.write(pageContext, sb.toString());

        return SKIP_BODY;
    }

    /**
     * Release any acquired resources.
     */
    public void release() {
        super.release();
        filter = true;
        label = "label";
        name = Constants.BEAN_KEY;
        property = null;
        style = null;
        styleClass = null;
        value = "value";
    }

    // ------------------------------------------------------ Protected Methods

    /**
     * Add an option element to the specified StringBuffer based on the
     * specified parameters.
     *<p>
     * Note that this tag specifically does not support the
     * <code>styleId</code> tag attribute, which causes the HTML
     * <code>id</code> attribute to be emitted.  This is because the HTML
     * specification states that all "id" attributes in a document have to be
     * unique.  This tag will likely generate more than one <code>option</code>
     * element element, but it cannot use the same <code>id</code> value.  It's
     * conceivable some sort of mechanism to supply an array of <code>id</code>
     * values could be devised, but that doesn't seem to be worth the trouble.
     *
     * @param sb StringBuffer accumulating our results
     * @param value Value to be returned to the server for this option
     * @param label Value to be shown to the user for this option
     * @param matched Should this value be marked as selected?
     */
    protected void addOption(StringBuffer sb, String label, String value, boolean matched) {

        sb.append("<option value=\"");
        sb.append(value);
        sb.append("\"");
        if (matched) {
            sb.append(" selected=\"selected\"");
        }
        if (style != null) {
            sb.append(" style=\"");
            sb.append(style);
            sb.append("\"");
        }
        if (styleClass != null) {
            sb.append(" class=\"");
            sb.append(styleClass);
            sb.append("\"");
        }
        sb.append(">");
        if (filter) {
            sb.append(ResponseUtils.filter(label));
        } else {
            sb.append(label);
        }
        sb.append("</option>\r\n");

    }

    /**
     * Return an iterator for the options collection.
     *
     * @param collection Collection to be iterated over
     *
     * @exception JspException if an error occurs
     */
    protected Iterator getIterator(Object collection) throws JspException {

        if (collection.getClass().isArray()) {
            collection = Arrays.asList((Object[]) collection);
        }

        if (collection instanceof Collection) {
            return (((Collection) collection).iterator());

        } else if (collection instanceof Iterator) {
            return ((Iterator) collection);

        } else if (collection instanceof Map) {
            return (((Map) collection).entrySet().iterator());

        } else if (collection instanceof Enumeration) {
            return IteratorUtils.asIterator((Enumeration) collection);

        } else {
            throw new JspException(
                messages.getMessage("optionsCollectionTag.iterator", collection.toString()));
        }
    }

}