Initial commit.

src/main/java/org/springframework/hateoas/Link.java

@@ -0,0 +1,138 @@
+/*
+ * Copyright 2012 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 org.springframework.hateoas;
+
+import java.io.Serializable;
+
+import javax.xml.bind.annotation.XmlAttribute;
+import javax.xml.bind.annotation.XmlType;
+
+import org.springframework.util.Assert;
+
+/**
+ * Value object for links.
+ * 
+ * @author Oliver Gierke
+ */
+@XmlType(name = "link", namespace = Link.ATOM_NAMESPACE)
+public class Link implements Serializable {
+
+	private static final long serialVersionUID = -9037755944661782121L;
+
+	public static final String ATOM_NAMESPACE = "http://www.w3.org/2005/Atom";
+
+	public static final String REL_SELF = "self";
+	public static final String REL_FIRST = "first";
+	public static final String REL_PREVIOUS = "previous";
+	public static final String REL_NEXT = "next";
+	public static final String REL_LAST = "last";
+
+	@XmlAttribute
+	private String rel;
+	@XmlAttribute
+	private String href;
+
+	/**
+	 * Creates a new link to the given URI with the self rel.
+	 * 
+	 * @see #REL_SELF
+	 * @param href must not be {@literal null} or empty.
+	 */
+	public Link(String href) {
+		this(href, REL_SELF);
+	}
+
+	/**
+	 * Creates a new {@link Link} to the given URI with the given rel.
+	 * 
+	 * @param href must not be {@literal null} or empty.
+	 * @param rel must not be {@literal null} or empty.
+	 */
+	public Link(String href, String rel) {
+
+		Assert.hasText(href, "Href must not be null or empty!");
+		Assert.hasText(rel, "Rel must not be null or empty!");
+
+		this.href = href;
+		this.rel = rel;
+	}
+
+	/**
+	 * Empty constructor required by the marshalling framework.
+	 */
+	protected Link() {
+
+	}
+
+	/**
+	 * Returns the actual URI the link is pointing to.
+	 * 
+	 * @return
+	 */
+	public String getHref() {
+		return href;
+	}
+
+	/**
+	 * Returns the rel of the link.
+	 * 
+	 * @return
+	 */
+	public String getRel() {
+		return rel;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see java.lang.Object#equals(java.lang.Object)
+	 */
+	@Override
+	public boolean equals(Object obj) {
+
+		if (this == obj) {
+			return true;
+		}
+
+		if (!(obj instanceof Link)) {
+			return false;
+		}
+
+		Link that = (Link) obj;
+
+		return this.href.equals(that.href) && this.rel.equals(that.rel);
+	}
+
+	/* (non-Javadoc)
+	 * @see java.lang.Object#hashCode()
+	 */
+	@Override
+	public int hashCode() {
+
+		int result = 17;
+		result += 31 * href.hashCode();
+		result += 31 * rel.hashCode();
+		return result;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		return String.format("{ rel : %s, href : %s }", rel, href);
+	}
+}