LabelRenderer.java

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// LabelRenderer.java

package com.sun.faces.renderkit.html_basic;

import java.io.IOException;
import java.util.logging.Level;

import javax.faces.component.NamingContainer;
import javax.faces.component.UIComponent;
import javax.faces.component.UINamingContainer;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;

import com.sun.faces.renderkit.Attribute;
import com.sun.faces.renderkit.AttributeManager;
import com.sun.faces.renderkit.RenderKitUtils;
import java.util.EnumSet;
import java.util.Set;
import javax.faces.component.search.SearchExpressionContext;
import javax.faces.component.search.SearchExpressionHint;

/** <p><B>LabelRenderer</B> renders Label element.<p>. */
public class LabelRenderer extends HtmlBasicInputRenderer {


    private static final Attribute[] ATTRIBUTES =
          AttributeManager.getAttributes(AttributeManager.Key.OUTPUTLABEL);


    private static final String RENDER_END_ELEMENT =
          "com.sun.faces.RENDER_END_ELEMENT";

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

    private static final Set<SearchExpressionHint> EXPRESSION_HINTS =
            EnumSet.of(SearchExpressionHint.RESOLVE_SINGLE_COMPONENT, SearchExpressionHint.IGNORE_NO_RESULT);
    
    @Override
    public void encodeBegin(FacesContext context, UIComponent component)
          throws IOException {

        rendererParamsNotNull(context, component);

        if (!shouldEncode(component)) {
            return;
        }

        ResponseWriter writer = context.getResponseWriter();
        assert(writer != null);

        String forClientId = null;
        String forValue = (String) component.getAttributes().get("for");
        if (forValue != null) {
            SearchExpressionContext searchExpressionContext =
                    SearchExpressionContext.createSearchExpressionContext(context, component,
                            EXPRESSION_HINTS, null);
        
            forClientId = context.getApplication().getSearchExpressionHandler().resolveClientId(
                searchExpressionContext, forValue);

            if (forClientId == null) {
                // it could that the component hasn't been created yet. So
                // construct the clientId for component.
                forClientId = getForComponentClientId(component, context, forValue);
            }
        }

        // set a temporary attribute on the component to indicate that
        // label end element needs to be rendered.
        component.getAttributes().put(RENDER_END_ELEMENT, "yes");
        writer.startElement("label", component);
        writeIdAttributeIfNecessary(context, writer, component);
        if (forClientId != null) {
            writer.writeAttribute("for", forClientId, "for");
        }

        RenderKitUtils.renderPassThruAttributes(context,
                                                writer,
                                                component,
                                                ATTRIBUTES);
        String styleClass = (String)
            component.getAttributes().get("styleClass");
        if (null != styleClass) {
            writer.writeAttribute("class", styleClass, "styleClass");
        }

        // render the curentValue as label text if specified.
        String value = getCurrentValue(context, component);
        if (logger.isLoggable(Level.FINE)) {
            logger.fine("Value to be rendered " + value);
        }
        if (value != null && value.length() != 0) {
            Object val = component.getAttributes().get("escape");
            boolean escape = (val != null) && Boolean.valueOf(val.toString());

            if (escape) {
                writer.writeText(value, component, "value");
            } else {
                writer.write(value);
            }
        }
        writer.flush();

    }


    @Override
    public void encodeEnd(FacesContext context, UIComponent component)
          throws IOException {

        rendererParamsNotNull(context, component);

        if (!shouldEncode(component)) {
            return;
        }

        // render label end element if RENDER_END_ELEMENT is set.
        String render = (String) component.getAttributes().get(
              RENDER_END_ELEMENT);
        if ("yes".equals(render)) {
            component.getAttributes().remove(RENDER_END_ELEMENT);
            ResponseWriter writer = context.getResponseWriter();
            assert(writer != null);
            writer.endElement("label");
        }

    }

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


    /**
     * Builds and returns the clientId of the component that is
     * represented by the forValue. Since the component has not been created
     * yet, invoking <code>getClientId(context)</code> is not possible.
     *
     * @param component UIComponent that represents the label
     * @param context   FacesContext for this request
     * @param forValue  String representing the "id" of the component
     *                  that this label represents.
     *
     * @return String clientId of the component represented by the forValue.
     */
    protected String getForComponentClientId(UIComponent component,
                                             FacesContext context,
                                             String forValue) {

        String result = null;
        // ASSUMPTION: The component for which this acts as the label
        // as well ths label component are part of the same form.
        // locate the nearest NamingContainer and get its clientId.
        UIComponent parent = component.getParent();
        while (parent != null) {
            if (parent instanceof NamingContainer) {
                break;
            }
            parent = parent.getParent();
        }
        if (parent == null) {
            return result;
        }
        String parentClientId = parent.getClientId(context);
        // prepend the clientId of the nearest container to the forValue.
        result = parentClientId + UINamingContainer.getSeparatorChar(context) + forValue;
        return result;

    }

    // The testcase for this class is TestRenderResponsePhase.java

} // end of class LabelRenderer