arearenderer.java

《j2ee经典实例详解》的源代码。原书无附带光盘。介绍的是一个在线银行系统的例子。绝对难得

/*
 * Copyright (c) 2005 Sun Microsystems, Inc.  All rights reserved.  U.S.
 * Government Rights - Commercial software.  Government users are subject
 * to the Sun Microsystems, Inc. standard license agreement and
 * applicable provisions of the FAR and its supplements.  Use is subject
 * to license terms.
 *
 * This distribution may include materials developed by third parties.
 * Sun, Sun Microsystems, the Sun logo, Java and J2EE are trademarks
 * or registered trademarks of Sun Microsystems, Inc. in the U.S. and
 * other countries.
 *
 * Copyright (c) 2005 Sun Microsystems, Inc. Tous droits reserves.
 *
 * Droits du gouvernement americain, utilisateurs gouvernementaux - logiciel
 * commercial. Les utilisateurs gouvernementaux sont soumis au contrat de
 * licence standard de Sun Microsystems, Inc., ainsi qu'aux dispositions
 * en vigueur de la FAR (Federal Acquisition Regulations) et des
 * supplements a celles-ci.  Distribue par des licences qui en
 * restreignent l'utilisation.
 *
 * Cette distribution peut comprendre des composants developpes par des
 * tierces parties. Sun, Sun Microsystems, le logo Sun, Java et J2EE
 * sont des marques de fabrique ou des marques deposees de Sun
 * Microsystems, Inc. aux Etats-Unis et dans d'autres pays.
 */


package renderers;

import components.AreaComponent;
import components.MapComponent;
import model.ImageArea;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;
import java.io.IOException;


/**
 * This class converts the internal representation of a <code>UIArea</code>
 * component into the output stream associated with the response to a
 * particular request.
 */
public class AreaRenderer extends BaseRenderer {
    // -------------------------------------------------------- Renderer Methods

    /**
     * <p>No decoding is required.</p>
     *
     * @param context   <code>FacesContext</code>for the current request
     * @param component <code>UIComponent</code> to be decoded
     */
    public void decode(FacesContext context, UIComponent component) {
        if ((context == null) || (component == null)) {
            throw new NullPointerException();
        }
    }

    /**
     * <p>No begin encoding is required.</p>
     *
     * @param context   <code>FacesContext</code>for the current request
     * @param component <code>UIComponent</code> to be decoded
     */
    public void encodeBegin(FacesContext context, UIComponent component)
        throws IOException {
        if ((context == null) || (component == null)) {
            throw new NullPointerException();
        }
    }

    /**
     * <p>No children encoding is required.</p>
     *
     * @param context   <code>FacesContext</code>for the current request
     * @param component <code>UIComponent</code> to be decoded
     */
    public void encodeChildren(FacesContext context, UIComponent component)
        throws IOException {
        if ((context == null) || (component == null)) {
            throw new NullPointerException();
        }
    }

    /**
     * <p>Encode this component.</p>
     *
     * @param context   <code>FacesContext</code>for the current request
     * @param component <code>UIComponent</code> to be decoded
     */
    public void encodeEnd(FacesContext context, UIComponent component)
        throws IOException {
        if ((context == null) || (component == null)) {
            throw new NullPointerException();
        }

        AreaComponent area = (AreaComponent) component;
        String targetImageId =
            area.findComponent(area.getTargetImage())
                .getClientId(context);
        ImageArea iarea = (ImageArea) area.getValue();
        ResponseWriter writer = context.getResponseWriter();
        StringBuffer sb = null;

        writer.startElement("area", area);
        writer.writeAttribute("alt", iarea.getAlt(), "alt");
        writer.writeAttribute("coords", iarea.getCoords(), "coords");
        writer.writeAttribute("shape", iarea.getShape(), "shape");

        // PENDING(craigmcc) - onmouseout only works on first form of a page
        sb = new StringBuffer("document.forms[0]['").append(targetImageId)
                                                    .append("'].src='");
        sb.append(getURI(context,
                (String) area.getAttributes().get("onmouseout")));
        sb.append("'");
        writer.writeAttribute("onmouseout", sb.toString(), "onmouseout");

        // PENDING(craigmcc) - onmouseover only works on first form of a page
        sb = new StringBuffer("document.forms[0]['").append(targetImageId)
                                                    .append("'].src='");
        sb.append(getURI(context,
                (String) area.getAttributes().get("onmouseover")));
        sb.append("'");
        writer.writeAttribute("onmouseover", sb.toString(), "onmouseover");

        // PENDING(craigmcc) - onclick only works on first form of a page
        sb = new StringBuffer("document.forms[0]['");
        sb.append(getName(context, area));
        sb.append("'].value='");
        sb.append(iarea.getAlt());
        sb.append("'; document.forms[0].submit()");
        writer.writeAttribute("onclick", sb.toString(), "value");
        writer.endElement("area");
    }

    // --------------------------------------------------------- Private Methods

    /**
     * <p>Return the calculated name for the hidden input field.</p>
     *
     * @param context   Context for the current request
     * @param component Component we are rendering
     */
    private String getName(FacesContext context, UIComponent component) {
        while (component != null) {
            if (component instanceof MapComponent) {
                return (component.getId() + "_current");
            }

            component = component.getParent();
        }

        throw new IllegalArgumentException();
    }

    /**
     * <p>Return the path to be passed into JavaScript for the specified
     * value.</p>
     *
     * @param context Context for the current request
     * @param value   Partial path to be (potentially) modified
     */
    private String getURI(FacesContext context, String value) {
        if (value.startsWith("/")) {
            return (context.getExternalContext()
                           .getRequestContextPath() + value);
        } else {
            return (value);
        }
    }
}