actionstag.java

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/*
 * Copyright 2001,2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package netstore.framework.tag;


import java.io.IOException;
import java.net.URLEncoder;
import java.util.ArrayList;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.BodyTagSupport;


/**
 * <p>JSP custom tag that renders an "instant actions" control.  To the user,
 * it appears as an HTML &lt;select&gt; element (i.e. a combo box), with
 * the behavior of selecting a new page for the current frame or window when
 * a different option is selected, without requiring a submit action.
 * This tag has the following user-settable attributes:</p>
 * <ul>
 * <li><strong>size</strong> - (Integer) number of rows that will be visible
 *     to the user.  If not specified, one row will be visible.</li>
 * <li><strong>style</strong> - The CSS style class to be applied to the
 *     entire rendered output of the instant actions control, if any.</li>
 * </ul>
 *
 * <strong>FIXME</strong> - Internationalize the exception messages!
 *
 * @author Craig R. McClanahan
 * @version $Revision: 1.3 $ $Date: 2004/02/27 14:59:01 $
 */

public class ActionsTag extends BodyTagSupport {


    // ----------------------------------------------------- Manifest Constants


    /**
     * Attribute name used to indicate that we have generated the JavaScript
     * function already on the current page.  The value stored for this
     * attribute is arbitrary - only its existence is relevant.
     */
    protected static final String FUNCTION_TAG =
        "org.apache.webapp.admin.ActionsTag.FUNCTION_TAG";


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


    /**
     * The set of labels for the Actions displayed by this control.
     */
    protected ArrayList labels = new ArrayList();


    /**
     * The set of "selected" flags for Actions displayed by this control.
     */
    protected ArrayList selecteds = new ArrayList();

    /**
     * The set of "disabled" flags for Actions displayed by this control.
     */
    protected ArrayList disableds = new ArrayList();

    /**
     * The set of URLs for the Actions displayed by this control.
     */
    protected ArrayList urls = new ArrayList();


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


    /**
     * The number of elements that will be displayed to the user.
     */
    protected int size = 1;

    public int getSize() {
        return (this.size);
    }

    public void setSize(int size) {
        this.size = size;
    }


    /**
     * The CSS style class to be applied to the entire rendered output
     * of this "instant actions" object.
     */
    protected String style = null;

    public String getStyle() {
        return (this.style);
    }

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


    /**
     *  HTML Label tag text.
     */
    protected String label = null;

    public String getLabel() {
        return (this.label);
    }

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


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

    public int doStartTag() throws JspException {

        this.labels.clear();
        this.selecteds.clear();
        this.urls.clear();

        return (EVAL_BODY_TAG);
       
    }
    
    
    /**
     * Render this instant actions control.
     *
     * @exception JspException if a processing error occurs
     */
    public int doEndTag() throws JspException {

        JspWriter out = pageContext.getOut();

        try {

            // Render (once only) the JavaScript function we need
            if (pageContext.getAttribute(FUNCTION_TAG) == null) {
                out.println();
                out.println("<script language=\"JavaScript\">");
                out.println("<!--");
                out.println("function IA_jumpMenu(targ,selObj) {");
                out.println("  dest = selObj.options[selObj.selectedIndex].value;");
                out.println("  if (dest.length > 0) {");
                out.println("    eval(targ+\".location='\"+dest+\"'\");");
                out.println("  }");
                out.println("}");
                out.println("//-->");
                out.println("</script>");
                out.println();
                pageContext.setAttribute(FUNCTION_TAG, Boolean.TRUE);
            }

            // Render LABEL element for section 508 accessibility
            
            if (label != null) {
                out.print("<label for=\"labelId\">");
                out.print(label);
                out.println("</label>");
            }
            // Render the beginning of this element
            out.println();
            out.print("<select");
            if (size > 1) {
                out.print(" size=\"");
                out.print(size);
                out.print("\"");
            }
            if (style != null) {
                out.print(" class=\"");
                out.print(style);
                out.print("\"");
            }
            if (label != null) {
                out.print(" id=\"");
                out.print("labelId");
                out.print("\"");
            }
            
            out.print(" onchange=\"IA_jumpMenu('self',this)\"");
            out.println(">");

            // Render each defined action
            int n = labels.size();
            for (int i = 0; i < n; i++) {
                String label = (String) labels.get(i);
                boolean selected = ((Boolean) selecteds.get(i)).booleanValue();
                boolean disabled = ((Boolean) disableds.get(i)).booleanValue();             
                String url = (String) urls.get(i);
                out.print("<option");
                if (selected)
                    out.print(" selected=\"selected\"");
                if (disabled)
                    out.print(" disabled=\"true\"");                
                out.print(" value=\"");
                if (url != null)
                    out.print(url);
                out.print("\"");
                out.print(">");
                if (label != null)
                    out.print(label);
                out.println("</option>");
            }

            // Render the end of this element
            out.println("</select>");
            out.println();

        } catch (IOException e) {
            throw new JspException(e);
        }

        return (EVAL_PAGE);

    }


    /**
     * Release all state information set by this tag.
     */
    public void release() {

        this.labels.clear();
        this.selecteds.clear();
        this.urls.clear();

        this.size = 1;
        this.style = null;

    }


    // -------------------------------------------------------- Package Methods


    /**
     * Add a new Action to the set that will be rendered by this control.
     *
     * @param label Localized label visible to the user
     * @param selected Initial selected state of this option
     * @param disabled Ability to be selected state of this option
     * @param url URL to which control should be transferred if selected
     */
    void addAction(String label, boolean selected, boolean disabled, String url) {

        labels.add(label);
        selecteds.add(new Boolean(selected));
        disableds.add(new Boolean(disabled));
        urls.add(url);

    }


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


}