htmlformrenderer.java

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/*
 * Copyright 2002-2004 the original author or authors.
 *
 * 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 de.mindmatters.faces.render.html;

import java.io.IOException;

import javax.faces.FactoryFinder;
import javax.faces.component.ActionSource;
import javax.faces.component.UIComponent;
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 javax.faces.render.RenderKit;
import javax.faces.render.RenderKitFactory;
import javax.faces.render.Renderer;

import org.springframework.util.Assert;

import de.mindmatters.faces.FacesUtils;
import de.mindmatters.faces.application.ViewBuilder;

/**
 * <strong>HtmlFormRenderer</strong> is a class that renders a
 * <code>UIForm</code> as a HTML Form.
 * 
 * @author Andreas Kuhrwahl
 * 
 */
public final class HtmlFormRenderer extends AbstractRendererBase {

    /** The original form renderer of the underlying JSF implementation. */
    private Renderer formRenderer;

    /**
     * {@inheritDoc}
     */
    public void decode(final FacesContext context, final UIComponent component) {
        getOriginalHtmlFormRenderer().decode(context, component);
        if (context.getExternalContext().getRequestParameterMap().containsKey(
                component.getClientId(context))) {
            ActionEvent actionEvent = new ActionEvent(component);
            component.queueEvent(actionEvent);
        }

    }

    /**
     * {@inheritDoc}
     */
    public void encodeBegin(final FacesContext context,
            final UIComponent component) throws IOException {
        if (context == null || component == null) {
            throw new NullPointerException("FacesContext or component");
        }
        if (component.isRendered()) {
            ResponseWriter writer = context.getResponseWriter();
            writer.startElement("form", component);
            String clientId = component.getClientId(context);
            writer.writeAttribute("id", clientId, null);
            writer.writeAttribute("name", clientId, null);
            writer.writeAttribute("method", component.getAttributes().get(
                    "method"), "method");
            writer.writeAttribute("action", getAction(context, component),
                    "action");
            String styleClass = (String) component.getAttributes().get(
                    "styleClass");
            if (styleClass != null) {
                writer.writeAttribute("class", styleClass, "styleClass");
            }
            String acceptcharset = (String) component.getAttributes().get(
                    "acceptcharset");
            if (acceptcharset != null) {
                writer.writeAttribute("accept-charset", acceptcharset,
                        "acceptcharset");
            }
            writePassThruAttributes(writer, component);
            writeBooleanPassThruAttributes(writer, component);
            writer.writeText("\n", null);
        }
    }

    /**
     * Evaluates the action attribute of the form <code>component</code>.
     * 
     * @param context
     *            {@link FacesContext} for the current request
     * @param component
     *            The associated UIComponent
     * @return The action value for the action attribute.
     */
    private String getAction(final FacesContext context,
            final UIComponent component) {
        String action = null;
        if (component instanceof ActionSource) {
            MethodBinding actionBinding = ((ActionSource) component)
                    .getAction();
            if (actionBinding != null) {
                action = (String) actionBinding.invoke(context, null);
            }
        }
        if (action == null) {
            String viewId = context.getViewRoot().getViewId();
            action = context.getApplication().getViewHandler().getActionURL(
                    context, viewId);
        }
        return context.getExternalContext().encodeActionURL(action);
    }

    /**
     * {@inheritDoc}
     */
    public void encodeEnd(final FacesContext context,
            final UIComponent component) throws IOException {
        if (component.isRendered()) {
            ResponseWriter writer = context.getResponseWriter();
            writer.startElement("input", null);
            writer.writeAttribute("type", "hidden", null);
            writer.writeAttribute("name", FacesUtils.VIEWID_PARAM, null);
            writer.writeAttribute("id", FacesUtils.VIEWID_PARAM, null);
            writer.writeAttribute("value", FacesUtils.encodeViewId(context),
                    null);
            writer.endElement("input");
            writer.startElement("input", null);
            writer.writeAttribute("type", "hidden", null);
            writer.writeAttribute("name", component.getClientId(context), null);
            writer.writeAttribute("id", component.getClientId(context), null);
            writer.endElement("input");
            if (component.isTransient()
                    && "post".equals(component.getAttributes().get("method"))) {
                writer.startElement("input", null);
                writer.writeAttribute("type", "hidden", null);
                writer.writeAttribute("name", FacesUtils.TRANSIENT_PARAM, null);
                writer.writeAttribute("id", FacesUtils.TRANSIENT_PARAM, null);
                writer
                        .writeAttribute("value", FacesUtils.TRANSIENT_PARAM,
                                null);
                writer.endElement("input");
            }
        }
        boolean isTransient = component.isTransient();
        if (isTransient) {
            ViewBuilder.markForTransientState(context);
        }
        try {
            getOriginalHtmlFormRenderer().encodeEnd(context, component);
        } finally {
            if (isTransient) {
                ViewBuilder.unmarkTransientState(context);
            }
        }
    }

    /**
     * {@inheritDoc}
     */
    public String convertClientId(final FacesContext context,
            final String clientId) {
        return getOriginalHtmlFormRenderer().convertClientId(context, clientId);
    }

    /**
     * {@inheritDoc}
     */
    public void encodeChildren(final FacesContext context,
            final UIComponent component) throws IOException {
        getOriginalHtmlFormRenderer().encodeChildren(context, component);
    }

    /**
     * {@inheritDoc}
     */
    public Object getConvertedValue(final FacesContext context,
            final UIComponent component, final Object submittedValue) {
        return getOriginalHtmlFormRenderer().getConvertedValue(context,
                component, submittedValue);
    }

    /**
     * {@inheritDoc}
     */
    public boolean getRendersChildren() {
        return getOriginalHtmlFormRenderer().getRendersChildren();
    }

    /**
     * Returns the original form renderer of the underlying JSF implementation.
     * 
     * @return The original form renderer.
     */
    private Renderer getOriginalHtmlFormRenderer() {
        if (this.formRenderer == null) {
            RenderKit renderKit = ((RenderKitFactory) FactoryFinder
                    .getFactory(FactoryFinder.RENDER_KIT_FACTORY))
                    .getRenderKit(null, RenderKitFactory.HTML_BASIC_RENDER_KIT);
            this.formRenderer = renderKit.getRenderer(UIForm.COMPONENT_FAMILY,
                    "javax.faces.Form");
            Assert.notNull(this.formRenderer);
        }
        return formRenderer;
    }

}