LinkTagHDIV.java

/**
 * Copyright 2005-2016 hdiv.org
 *
 * 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 org.hdiv.taglib.html;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;

import org.apache.struts.taglib.TagUtils;
import org.apache.struts.taglib.html.LinkTag;
import org.hdiv.urlProcessor.LinkUrlProcessor;
import org.hdiv.util.HDIVUtil;

/**
 * Generate a URL-encoded hyperlink to the specified URI.
 *
 * @author Aritz Rabadan
 * @author Gorka Vicente
 * @see org.apache.struts.taglib.html.LinkTag
 */
public class LinkTagHDIV extends LinkTag {

	/**
	 * Universal version identifier. Deserialization uses this number to ensure that a loaded class corresponds exactly to a serialized
	 * object.
	 */
	private static final long serialVersionUID = -376718532211972980L;

	protected LinkUrlProcessor linkUrlProcessor;

	/**
	 * Render the end of the hyperlink.
	 *
	 * @exception JspException if a JSP exception has occurred
	 */
	@Override
	public int doEndTag() throws JspException {

		final HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();

		// Validate if any specifier was included
		if ((forward == null) && (href == null) && (page == null) && (action == null)) {
			return super.doEndTag();
		}

		// the value specified in linkname will render a "name" element in the
		// generated anchor tag
		if (getLinkName() != null) {
			return super.doEndTag();
		}

		// return the complete URL to which this hyperlink will direct the user.
		final String url = calculateURL();

		// Generate the opening anchor element
		final StringBuilder results = new StringBuilder("<a");

		// If useLocalEncoding set to true, urlencoding is done on the bytes of
		// character encoding from ServletResponse#getCharacterEncoding. Use UTF-8
		// otherwise.
		String charEncoding = "UTF-8";
		if (useLocalEncoding) {
			charEncoding = pageContext.getResponse().getCharacterEncoding();
		}

		// Call to Hdiv LinkUrlProcessor
		if (linkUrlProcessor == null) {
			linkUrlProcessor = HDIVUtil.getLinkUrlProcessor(request.getSession().getServletContext());
		}
		final String urlWithHDIVParameter = linkUrlProcessor.processUrl(request, url, charEncoding);

		renderAttribute(results, "href", urlWithHDIVParameter);

		renderAttribute(results, "target", getTarget());
		renderAttribute(results, "accesskey", getAccesskey());
		renderAttribute(results, "tabindex", getTabindex());

		results.append(prepareStyles());
		results.append(prepareEventHandlers());
		prepareOtherAttributes(results);
		results.append(">");

		// Prepare the textual content and ending element of this hyperlink
		if (text != null) {
			results.append(text);
		}
		results.append("</a>");
		TagUtils.getInstance().write(pageContext, results.toString());

		return (EVAL_PAGE);
	}

	/**
	 * Prepares an attribute if the <code>value</code> is not null, appending it to the the given StringBuilder <code>result</code>.
	 *
	 * @param result The StringBuilder that output will be appended to.
	 */
	private void renderAttribute(final StringBuilder result, final String name, final String value) {

		if (value != null) {
			result.append(" ");
			result.append(name);
			result.append("=\"");
			result.append(value);
			result.append("\"");
		}
	}

	/**
	 * 'Hook' to enable tags to be extended and additional attributes added.
	 *
	 * @param handlers The StringBuilder that output will be appended to.
	 */
	protected void prepareOtherAttributes(final StringBuilder handlers) {

	}

}