Link.java

/*
 * This library is free software; you can redistribute it and/or modify it under the terms of
 * the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE. See the GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301 USA
 */
package com.restfully.shop.domain;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlRootElement;
import java.util.HashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @version $Revision: 1 $
 */
@XmlRootElement(name = "link")
public class Link
{
   protected String relationship;
   protected String href;
   protected String type;

   public Link()
   {
   }

   public Link(String relationship, String href, String type)
   {
      this.relationship = relationship;
      this.href = href;
      this.type = type;
   }

   @XmlAttribute(name = "rel")
   public String getRelationship()
   {
      return relationship;
   }

   public void setRelationship(String relationship)
   {
      this.relationship = relationship;
   }

   @XmlAttribute
   public String getHref()
   {
      return href;
   }

   public void setHref(String href)
   {
      this.href = href;
   }

   @XmlAttribute
   public String getType()
   {
      return type;
   }

   public void setType(String type)
   {
      this.type = type;
   }

   /**
    * To write as link header
    *
    * @return
    */
   public String toString()
   {
      StringBuilder builder = new StringBuilder("<");
      builder.append(href).append(">; rel=").append(relationship);
      if (type != null) builder.append("; type=").append(type);
      return builder.toString();
   }

   private static Pattern parse = Pattern.compile("<(.+)>\\s*;\\s*(.+)");

   /**
    * For unmarshalling Link Headers.
    * Its not an efficient or perfect algorithm and does make a few assumptiosn
    *
    * @param val
    * @return
    */
   public static Link valueOf(String val)
   {
      Matcher matcher = parse.matcher(val);
      if (!matcher.matches()) throw new RuntimeException("Failed to parse link: " + val);
      Link link = new Link();
      link.href = matcher.group(1);
      String[] props = matcher.group(2).split(";");
      HashMap<String, String> map = new HashMap();
      for (String prop : props)
      {
         String[] split = prop.split("=");
         map.put(split[0].trim(), split[1].trim());
      }
      if (map.containsKey("rel"))
      {
         link.relationship = map.get("rel");
      }
      if (map.containsKey("type"))
      {
         link.type = map.get("type");
      }
      return link;
   }
}