abstractrendererbase.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.component.UIComponent;
import javax.faces.context.ResponseWriter;
import javax.faces.render.Renderer;

import org.springframework.util.Assert;

/**
 * <strong>AbstractRendererBase</strong> is a convenience base class that
 * implements helper methods needed for any concrete renderer.
 * 
 * @author Andreas Kuhrwahl
 * 
 */
public abstract class AbstractRendererBase extends Renderer {

    /** The standard boolean "passthru" attributes. */
    private static String[] booleanPassthruAttributes = { "disabled",
            "readonly", "ismap" };

    /** The standard "passthru" attributes. */
    private static String[] passthruAttributes = { "accept", "accesskey",
            "alt", "bgcolor", "border", "cellpadding", "cellspacing",
            "charset", "cols", "coords", "dir", "enctype", "frame", "height",
            "hreflang", "lang", "longdesc", "maxlength", "onblur", "onchange",
            "onclick", "ondblclick", "onfocus", "onkeydown", "onkeypress",
            "onkeyup", "onload", "onmousedown", "onmousemove", "onmouseout",
            "onmouseover", "onmouseup", "onreset", "onselect", "onsubmit",
            "onunload", "rel", "rev", "rows", "rules", "shape", "size",
            "style", "summary", "tabindex", "target", "title", "usemap",
            "width" };

    /**
     * Converts an attribute of the given UIComponent <code>component</code>
     * with the name <code>attributeName</code> to a boolean value.
     * 
     * @param component
     *            The associated component
     * @param attributeName
     *            The name of the attribute to convert
     * @return <code>true</code> if the attribute exists and equals "true"
     *         <code>false</code> otherwise
     */
    protected final boolean getBooleanAttribute(final UIComponent component,
            final String attributeName) {
        Object attribute = component.getAttributes().get(attributeName);
        boolean result = false;
        if (attribute != null) {
            if (attribute instanceof Boolean) {
                result = ((Boolean) attribute).booleanValue();
            }
            if (attribute instanceof String) {
                result = ((String) attribute).equalsIgnoreCase("true");
            } else {
                if (!(attribute instanceof String)) {
                    attribute = attribute.toString();
                }
                result = Boolean.valueOf((String) attribute).booleanValue();
            }
        }
        return result;
    }

    /**
     * Render any boolean "passthru" attributes.
     * 
     * @param writer
     *            The Responsewriter to use
     * @param component
     *            The associated component
     * @throws IOException
     *             if an input/output error occurs
     * @see AbstractRendererBase#writePassThruAttributes(ResponseWriter,
     *      UIComponent)
     */
    protected final void writeBooleanPassThruAttributes(
            final ResponseWriter writer, final UIComponent component)
            throws IOException {
        Assert.notNull(writer);
        Assert.notNull(component);
        for (int i = 0; i < booleanPassthruAttributes.length; i++) {
            if (getBooleanAttribute(component, booleanPassthruAttributes[i])) {
                writer.writeAttribute(booleanPassthruAttributes[i],
                        booleanPassthruAttributes[i],
                        booleanPassthruAttributes[i]);
            }
        }
    }

    /**
     * Render any "passthru" attributes, where we simply just output the raw
     * name and value of the attribute. This method is aware of the set of HTML4
     * attributes that fall into this bucket. Examples are all the javascript
     * attributes, alt, rows, cols, etc.
     * 
     * @param writer
     *            The Responsewriter to use
     * @param component
     *            The associated component
     * @throws IOException
     *             if an input/output error occurs
     */
    protected final void writePassThruAttributes(final ResponseWriter writer,
            final UIComponent component) throws IOException {
        Assert.notNull(writer);
        Assert.notNull(component);
        Object value = null;
        for (int i = 0; i < passthruAttributes.length; i++) {
            value = component.getAttributes().get(passthruAttributes[i]);
            if (value != null) {
                if (!(value instanceof String)) {
                    value = value.toString();
                }
                writer.writeAttribute(passthruAttributes[i], value,
                        passthruAttributes[i]);
            }
        }
    }

}