scrollercomponent.java

一个虚拟训练系统.主要使用j2ee框架实现.

package com.jsfcompref.trainer.components;
import javax.faces.component.UICommand;

/*
 * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 * 
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * 
 * - Redistribution 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.
 *    
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 *  
 * This software is provided "AS IS," without a warranty of any
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY
 * DAMAGES OR LIABILITIES SUFFERED BY LICENSEE AS A RESULT OF OR
 * RELATING TO USE, MODIFICATION OR DISTRIBUTION OF THIS SOFTWARE OR
 * ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE
 * FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT,
 * SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF
 * THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS
 * BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *  
 * You acknowledge that this software is not designed, licensed or
 * intended for use in the design, construction, operation or
 * maintenance of any nuclear facility.
 */



//import components.renderkit.Util;

//import javax.faces.component.UICommand;
import javax.faces.component.UIComponent;
import javax.faces.component.UIData;
import javax.faces.component.UIForm;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;
import javax.faces.el.MethodBinding;
import javax.faces.event.ActionEvent;

import java.io.IOException;
import java.util.Map;

/**
 * This component produces a search engine style scroller that facilitates
 * easy navigation over results that span across several pages. It
 * demonstrates how a component can do decoding and encoding
 * without delegating it to a renderer.
 */
public class ScrollerComponent extends UICommand {

    public static final String NORTH = "NORTH";
    public static final String SOUTH = "SOUTH";
    public static final String EAST = "EAST";
    public static final String WEST = "WEST";
    public static final String BOTH = "BOTH";

    public static final int ACTION_NEXT = -1;
    public static final int ACTION_PREVIOUS = -2;
    public static final int ACTION_NUMBER = -3;

    public static final String FORM_NUMBER_ATTR = "com.sun.faces.FormNumber";

    /**
     * The component attribute that tells where to put the user supplied
     * markup in relation to the "jump to the Nth page of results"
     * widget.
     */
    public static final String FACET_MARKUP_ORIENTATION_ATTR =
        "navFacetOrientation";


    public ScrollerComponent() {
        super();
        this.setRendererType(null);
    }


    public void decode(FacesContext context) {
        String curPage = null;
        String action = null;
        int actionInt = 0;
        int currentPage = 1;
        int currentRow = 1;
        String clientId = getClientId(context);
        Map requestParameterMap = (Map) context.getExternalContext().
            getRequestParameterMap();
        action = (String) requestParameterMap.get(clientId + "_action");
        if (action == null || action.length() == 0) {
            // nothing to decode
            return;
        }
        MethodBinding mb = createConstantMethodBinding(action);

        this.getAttributes().put("action", mb);
        curPage = (String) requestParameterMap.get(clientId + "_curPage");
        currentPage = Integer.valueOf(curPage).intValue();

        // Assert that action's length is 1.
        switch (actionInt = Integer.valueOf(action).intValue()) {
            case ACTION_NEXT:
                currentPage++;
                break;
            case ACTION_PREVIOUS:
                currentPage--;
                // Assert 1 < currentPage
                break;
            default:
                currentPage = actionInt;
                break;
        } 
        // from the currentPage, calculate the current row to scroll to.
        currentRow = (currentPage - 1) * getRowsPerPage(context);
        this.getAttributes().put("currentPage", new Integer(currentPage));
        this.getAttributes().put("currentRow", new Integer(currentRow));
        this.queueEvent(new ActionEvent(this));
    }


    public void encodeBegin(FacesContext context) throws IOException {
        return;
    }


    public void encodeEnd(FacesContext context) throws IOException {
        int currentPage = 1;

        ResponseWriter writer = context.getResponseWriter();

        String clientId = getClientId(context);
        Integer curPage = (Integer) getAttributes().get("currentPage");
        if (curPage != null) {
            currentPage = curPage.intValue();
        }
        int totalPages = getTotalPages(context);
        

        writer.write("<table border=\"0\" cellpadding=\"0\" align=\"center\">");
        writer.write("<tr align=\"center\" valign=\"top\">");
        
       // Removed "Result Page: output" - Cschalk
       // writer.write( "<td><font size=\"-1\">Result&nbsp;Page:&nbsp;</font></td>");

        // write the Previous link if necessary
        writer.write("<td>");
        writeNavWidgetMarkup(context, clientId, ACTION_PREVIOUS,
                             (1 < currentPage));
        // last arg is true iff we're not the first page
        writer.write("</td>");

        // render the page navigation links
        int i = 0;
        int first = 1;
        int last = totalPages;

        if (10 < currentPage) {
            first = currentPage - 10;
        }
        if ((currentPage + 9) < totalPages) {
            last = currentPage + 9;
        }
        for (i = first; i <= last; i++) {
            writer.write("<td>");
            writeNavWidgetMarkup(context, clientId, i, (i != currentPage));
            writer.write("</td>");
        }

        // write the Next link if necessary
        writer.write("<td>");
        writeNavWidgetMarkup(context, clientId, ACTION_NEXT,
                             (currentPage < totalPages));
        writer.write("</td>");
        writer.write("</tr>");
        writer.write(getHiddenFields(clientId));
        writer.write("</table>");
    }


    public boolean getRendersChildren() {
        return true;
    }


    /**
     * <p>Return the component family for this component.</p>
     */
    public String getFamily() {

        return ("Scroller");

    }
     
    //
    // Helper methods
    // 

    /**
     * Write the markup to render a navigation widget.  Override this to
     * replace the default navigation widget of link with something
     * else.
     */
    protected void writeNavWidgetMarkup(FacesContext context,
                                        String clientId,
                                        int navActionType,
                                        boolean enabled) throws IOException {
        ResponseWriter writer = context.getResponseWriter();
        String facetOrientation = NORTH;
        String facetName = null;
        String linkText = null;
        String localLinkText = null;
        UIComponent facet = null;
        boolean isCurrentPage = false;
        boolean isPageNumber = false;

        // Assign values for local variables based on the navActionType
        switch (navActionType) {