maprenderer.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.MapComponent;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;
import java.io.IOException;


/**
 * <p>Renderer for {@link MapComponent} in an HTML environment.</p>
 */
public class MapRenderer extends BaseRenderer {
    // -------------------------------------------------------- Renderer Methods

    /**
     * <p>Decode the incoming request parameters to determine which
     * hotspot (if any) has been selected.</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();
        }

        MapComponent map = (MapComponent) component;

        String key = getName(context, map);
        String value =
            (String) context.getExternalContext()
                            .getRequestParameterMap()
                            .get(key);

        if (value != null) {
            map.setCurrent(value);
        }
    }

    /**
     * <p>Encode the beginning of this component.</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();
        }

        MapComponent map = (MapComponent) component;
        ResponseWriter writer = context.getResponseWriter();

        writer.startElement("map", map);
        writer.writeAttribute("name", map.getId(), "id");
    }

    /**
     * <p>Encode the children of this component.</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 the ending of 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();
        }

        MapComponent map = (MapComponent) component;
        ResponseWriter writer = context.getResponseWriter();

        writer.startElement("input", map);
        writer.writeAttribute("type", "hidden", null);
        writer.writeAttribute("name", getName(context, map), "clientId");
        writer.endElement("input");
        writer.endElement("map");
    }

    // --------------------------------------------------------- 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) {
        return (component.getId() + "_current");
    }

    /**
     * <p>Return the context-relative path for the current page.</p>
     *
     * @param context Context for the current request
     */
    private String getURI(FacesContext context) {
        StringBuffer sb = new StringBuffer();
        sb.append(context.getExternalContext().getRequestContextPath());

        // PENDING(craigmcc) - will need to change if this is generalized
        sb.append("/faces");
        sb.append(context.getViewRoot().getViewId());

        return (sb.toString());
    }
}