#567 - Add extra attributes to Link and use for HAL mediatype.

Adds many additional attributes defined in RFC5988 and verifies they work properly in the neutral representation of Link while also being rendered properly in the HAL module.

Related tickets: #100, #417, #235, #240, #238, #223

Author: gregturn

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -16,10 +16,13 @@
 package org.springframework.hateoas;
 
 import java.io.Serializable;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -37,6 +40,7 @@
  * Value object for links.
  * 
  * @author Oliver Gierke
+ * @author Greg Turnquist
  */
 @XmlType(name = "link", namespace = Link.ATOM_NAMESPACE)
 @JsonIgnoreProperties("templated")
@@ -55,6 +59,11 @@ public class Link implements Serializable {
 
 	@XmlAttribute private String rel;
 	@XmlAttribute private String href;
+	@XmlAttribute private String hreflang;
+	@XmlAttribute private String media;
+	@XmlAttribute private String title;
+	@XmlAttribute private String type;
+	@XmlAttribute private String deprecation;
 	@XmlTransient @JsonIgnore private UriTemplate template;
 
 	/**
@@ -85,14 +94,35 @@ public Link(String href, String rel) {
 	 */
 	public Link(UriTemplate template, String rel) {
 
-		Assert.notNull(template, "UriTempalte must not be null!");
+		Assert.notNull(template, "UriTemplate must not be null!");
 		Assert.hasText(rel, "Rel must not be null or empty!");
 
 		this.template = template;
 		this.href = template.toString();
 		this.rel = rel;
 	}
 
+	/**
+	 * Creates a new {@link Link} to the given URI with the given rel, hreflang, media, title, and type.
+	 *
+	 * @param href must not be {@literal null} or empty.
+	 * @param rel must not be {@literal null} or empty.
+	 * @param hreflang
+	 * @param media
+	 * @param title
+	 * @param type
+	 * @param deprecation
+	 */
+	public Link(String href, String rel, String hreflang, String media, String title, String type, String deprecation) {
+
+		this(href, rel);
+		this.hreflang = hreflang;
+		this.media = media;
+		this.title = title;
+		this.type = type;
+		this.deprecation = deprecation;
+	}
+
 	/**
 	 * Empty constructor required by the marshalling framework.
 	 */
@@ -118,6 +148,51 @@ public String getRel() {
 		return rel;
 	}
 
+	/**
+	 * Returns the hreflang of the link.
+	 *
+	 * @return
+	 */
+	public String getHreflang() {
+		return hreflang;
+	}
+
+	/**
+	 * Returns the media of the link.
+	 *
+	 * @return
+	 */
+	public String getMedia() {
+		return media;
+	}
+
+	/**
+	 * Returns the title of the link.
+	 *
+	 * @return
+	 */
+	public String getTitle() {
+		return title;
+	}
+
+	/**
+	 * Returns the type of the link
+	 *
+	 * @return
+	 */
+	public String getType() {
+		return type;
+	}
+
+	/**
+	 * Returns link about deprecation of this link.
+	 *
+	 * @return
+	 */
+	public String getDeprecation() {
+		return deprecation;
+	}
+	
 	/**
 	 * Returns a {@link Link} pointing to the same URI but with the given relation.
 	 * 
@@ -137,6 +212,61 @@ public Link withSelfRel() {
 		return withRel(Link.REL_SELF);
 	}
 
+	/**
+	 * Returns a {@link Link} with the {@code hreflang} attribute filled out.
+	 *
+	 * @param hreflang
+	 * @return
+	 */
+	public Link withHreflang(String hreflang) {
+		Assert.hasText(hreflang, "hreflang must not be null or empty!");
+		return new Link(this.href, this.rel, hreflang, this.media, this.title, this.type, this.deprecation);
+	}
+
+	/**
+	 * Returns a {@link Link} with the {@code media} attribute filled out.
+	 *
+	 * @param media
+	 * @return
+	 */
+	public Link withMedia(String media) {
+		Assert.hasText(media, "media must not be null or empty!");
+		return new Link(this.href, this.rel, this.hreflang, media, this.title, this.type, this.deprecation);
+	}
+
+	/**
+	 * Returns a {@link Link} with the {@code title} attribute filled out.
+	 *
+	 * @param title
+	 * @return
+	 */
+	public Link withTitle(String title) {
+		Assert.hasText(title, "title must not be null or empty!");
+		return new Link(this.href, this.rel, this.hreflang, this.media, title, this.type, this.deprecation);
+	}
+
+	/**
+	 * Returns a {@link Link} with the {@code type} attribute filled out.
+	 *
+	 * @param type
+	 * @return
+	 */
+	public Link withType(String type) {
+		Assert.hasText(type, "type must not be null or empty!");
+		return new Link(this.href, this.rel, this.hreflang, this.media, this.title, type, this.deprecation);
+	}
+
+	/**
+	 * Returns a {@link Link} with the {@code deprecation} attribute filled out.
+	 *
+	 * @param deprecation
+	 * @return
+	 */
+	public Link withDeprecation(String deprecation) {
+		Assert.hasText(deprecation, "deprecation must not be null or empty!");
+		return new Link(this.href, this.rel, this.hreflang, this.media, this.title, this.type, deprecation);
+	}
+	
 	/**
 	 * Returns the variable names contained in the template.
 	 * 
@@ -212,7 +342,20 @@ public boolean equals(Object obj) {
 
 		Link that = (Link) obj;
 
-		return this.href.equals(that.href) && this.rel.equals(that.rel);
+		return
+			this.href.equals(that.href)
+				&&
+				this.rel.equals(that.rel)
+				&&
+				(this.hreflang != null ? this.hreflang.equals(that.hreflang) : this.hreflang == that.hreflang)
+				&&
+				(this.media != null ? this.media.equals(that.media) : this.media == that.media)
+				&&
+				(this.title != null ? this.title.equals(that.title) : this.title == that.title)
+				&&
+				(this.type != null ? this.type.equals(that.type) : this.type == that.type)
+				&&
+				(this.deprecation != null ? this.deprecation.equals(that.deprecation) : this.deprecation == that.deprecation);
 	}
 
 	/* 
@@ -225,6 +368,21 @@ public int hashCode() {
 		int result = 17;
 		result += 31 * href.hashCode();
 		result += 31 * rel.hashCode();
+		if (hreflang != null) {
+			result += 31 * hreflang.hashCode();
+		}
+		if (media != null) {
+			result += 31 * media.hashCode();
+		}
+		if (title != null) {
+			result += 31 * title.hashCode();
+		}
+		if (type != null) {
+			result += 31 * type.hashCode();
+		}
+		if (deprecation != null) {
+			result += 31 * deprecation.hashCode();
+		}
 		return result;
 	}
 
@@ -234,7 +392,29 @@ public int hashCode() {
 	 */
 	@Override
 	public String toString() {
-		return String.format("<%s>;rel=\"%s\"", href, rel);
+		String linkString = String.format("<%s>;rel=\"%s\"", href, rel);
+
+		if (hreflang != null) {
+			linkString += ";hreflang=\"" + hreflang + "\"";
+		}
+
+		if (media != null) {
+			linkString += ";media=\"" + media + "\"";
+		}
+
+		if (title != null) {
+			linkString += ";title=\"" + title + "\"";
+		}
+
+		if (type != null) {
+			linkString += ";type=\"" + type + "\"";
+		}
+
+		if (deprecation != null) {
+			linkString += ";deprecation=\"" + deprecation + "\"";
+		}
+		
+		return linkString;
 	}
 
 	/**
@@ -263,7 +443,34 @@ public static Link valueOf(String element) {
 				throw new IllegalArgumentException("Link does not provide a rel attribute!");
 			}
 
-			return new Link(matcher.group(1), attributes.get("rel"));
+			Set<String> unrecognizedHeaders = unrecognizedHeaders(attributes);
+			if (!unrecognizedHeaders.isEmpty()) {
+				throw new IllegalArgumentException("Link contains invalid RFC5988 headers! => " + unrecognizedHeaders);
+			}
+
+			Link link = new Link(matcher.group(1), attributes.get("rel"));
+
+			if (attributes.containsKey("hreflang")) {
+				link = link.withHreflang(attributes.get("hreflang"));
+			}
+
+			if (attributes.containsKey("media")) {
+				link = link.withMedia(attributes.get("media"));
+			}
+
+			if (attributes.containsKey("title")) {
+				link = link.withTitle(attributes.get("title"));
+			}
+
+			if (attributes.containsKey("type")) {
+				link = link.withType(attributes.get("type"));
+			}
+
+			if (attributes.containsKey("deprecation")) {
+				link = link.withDeprecation(attributes.get("deprecation"));
+			}
+
+			return link;
 
 		} else {
 			throw new IllegalArgumentException(String.format("Given link header %s is not RFC5988 compliant!", element));
@@ -283,7 +490,7 @@ private static Map<String, String> getAttributeMap(String source) {
 		}
 
 		Map<String, String> attributes = new HashMap<String, String>();
-		Pattern keyAndValue = Pattern.compile("(\\w+)=\"(\\p{Lower}[\\p{Lower}\\p{Digit}\\.\\-]*|" + URI_PATTERN + ")\"");
+		Pattern keyAndValue = Pattern.compile("(\\w+)=\"(\\p{Lower}[\\p{Lower}\\p{Digit}\\.\\-\\s]*|" + URI_PATTERN + ")\"");
 		Matcher matcher = keyAndValue.matcher(source);
 
 		while (matcher.find()) {
@@ -292,4 +499,22 @@ private static Map<String, String> getAttributeMap(String source) {
 
 		return attributes;
 	}
+
+	/**
+	 * Scan for any headers not recognized.
+	 *
+	 * @param attributes
+	 * @return
+	 */
+	private static Set<String> unrecognizedHeaders(final Map<String, String> attributes) {
+
+		// Copy the existing keys to avoid damaging the original.
+		Set<String> unrecognizedHeaders = new HashSet<String>();
+		unrecognizedHeaders.addAll(attributes.keySet());
+
+		// Remove all recognized headers
+		unrecognizedHeaders.removeAll(Arrays.asList("href", "rel", "hreflang", "media", "title", "type", "deprecation"));
+
+		return unrecognizedHeaders;
+	}
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013-2017 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.
@@ -29,10 +29,11 @@
  * Value object to represent a list of {@link Link}s.
  * 
  * @author Oliver Gierke
+ * @author Greg Turnquist
  */
 public class Links implements Iterable<Link> {
 
-	private static final Pattern LINK_HEADER_PATTERN = Pattern.compile("(<[^>]*>;rel=\"[^\"]*\")");
+	private static final Pattern LINK_HEADER_PATTERN = Pattern.compile("(<[^>]*>(;\\w+=\"[^\"]*\")+)");
 
 	static final Links NO_LINKS = new Links(Collections.<Link> emptyList());