com.pushinginertia.wicket.core.behavior.CanonicalRefBehavior.java Source code

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Here is the source code for com.pushinginertia.wicket.core.behavior.CanonicalRefBehavior.java

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/* Copyright (c) 2011-2013 Pushing Inertia
 * All rights reserved.  http://pushinginertia.com
 *
 * 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 com.pushinginertia.wicket.core.behavior;

import com.pushinginertia.commons.core.validation.ValidateAs;
import com.pushinginertia.wicket.core.RequestCycleUtils;
import org.apache.wicket.Component;
import org.apache.wicket.behavior.Behavior;
import org.apache.wicket.markup.html.IHeaderResponse;
import org.apache.wicket.request.cycle.RequestCycle;

/**
 * Generates a rel="canonical" link to either the current page (without any arguments) or a given domain and page on that
 * domain. This is useful for pages with similar content, such as paginated search results.
 * <p>
 * Sample output:
 * <br/>
 * &lt;link rel="canonical" href="http://www.example.com/pagepath"/&gt;
 */
public class CanonicalRefBehavior extends Behavior {
    private static final long serialVersionUID = 1L;

    private final String domain;
    private final String path;

    /**
     * Generates a canonical link to a page on a given domain.
     * <p>
     * e.g.,
     * &lt;link rel="canonical" href="http://www.example.com/pagepath"&gt;
     * @param domain domain portion of the URL
     * @param path path portion of the URL
     */
    public CanonicalRefBehavior(final String domain, final String path) {
        this.domain = ValidateAs.notNull(domain, "domain");
        this.path = ValidateAs.notNull(path, "path");
    }

    /**
     * Builds a canonical link to the current page but without any page parameters.
     * Used for pages containing the same general content regardless of what parameters they are given and prevents
     * search engines from indexing the same page over and over with only variations in page parameters.
     */
    public CanonicalRefBehavior() {
        domain = RequestCycleUtils.getRequestHostName();
        path = RequestCycle.get().getUrlRenderer().getBaseUrl().getPath();
    }

    @Override
    public void renderHead(Component component, IHeaderResponse response) {
        final StringBuilder sb = new StringBuilder();
        sb.append("<link rel=\"canonical\" href=\"http://");
        sb.append(domain);
        sb.append('/');
        sb.append(path);
        sb.append("\"/>");
        response.renderString(sb.toString());
    }
}