I'm not too familiar with link injection, but one easy way to add links is to embed javax.ws.rs.core.Links into your JAXB entity classes. It comes with a built in XmlAdapter, Link.JaxbAdapter that will allow the Link type to be marshalled and unmarshalled by JAXB. Take for example you have a BookStore class that holds a collection of Books. It will also have Links from which you can control the navigational cases.
@XmlRootElement(name = "bookstore")
public class BookStore {
private List<Link> links;
private Collection<Book> books;
@XmlElementRef
public Collection<Book> getBooks() {
return books;
}
public void setBooks(Collection<Book> books) {
this.books = books;
}
@XmlElement(name = "link")
@XmlJavaTypeAdapter(Link.JaxbAdapter.class)
public List<Link> getLinks() {
return links;
}
public void setLinks(List<Link> links) {
this.links = links;
}
@XmlTransient
public URI getNext() {
if (links == null) {
return null;
}
for (Link link : links) {
if ("next".equals(link.getRel())) {
return link.getUri();
}
}
return null;
}
@XmlTransient
public URI getPrevious() {
if (links == null) {
return null;
}
for (Link link : links) {
if ("previous".equals(link.getRel())) {
return link.getUri();
}
}
return null;
}
}
The Book class is just a regular root element JAXB class
@XmlRootElement
public class Book {
@XmlAttribute
private String author;
@XmlAttribute
private String title;
public Book() {}
public Book(String title, String author) {
this.title = title;
this.author = author;
}
}
In the BookResource class, we can basically add links on demand based on your required logic of what links you want represented. In the example below, there is an in-memory db (this class is used as a stateful singleton class just for example) of books for which I add five books, with incrementing ids. When the request comes in, one or two links will be added to the returning BookStore. Depending on what id is being requested, we will add a "next" and/or a previous" link. The links will have rels that we refer to from our BookStore class.
@Path("/books")
public class BookResource {
private final Map<Integer, Book> booksDB
= Collections.synchronizedMap(new LinkedHashMap<Integer, Book>());
private final AtomicInteger idCounter = new AtomicInteger();
public BookResource() {
Book book = new Book("Book One", "Author One");
booksDB.put(idCounter.incrementAndGet(), book);
book = new Book("Book Two", "Author Two");
booksDB.put(idCounter.incrementAndGet(), book);
book = new Book("Book Three", "Author Three");
booksDB.put(idCounter.incrementAndGet(), book);
book = new Book("Book Four", "Author Four");
booksDB.put(idCounter.incrementAndGet(), book);
book = new Book("Book Five", "Author Five");
booksDB.put(idCounter.incrementAndGet(), book);
}
@GET
@Formatted
@Path("/{id}")
@Produces(MediaType.APPLICATION_XML)
public BookStore getBook(@Context UriInfo uriInfo, @PathParam("id") int id) {
List<Link> links = new ArrayList<>();
Collection<Book> books = new ArrayList<>();
UriBuilder uriBuilder = uriInfo.getBaseUriBuilder();
uriBuilder.path("books");
uriBuilder.path("{id}");
Book book = booksDB.get(id);
if (book == null) {
throw new WebApplicationException(Response.Status.NOT_FOUND);
}
synchronized(booksDB) {
if (id + 1 <= booksDB.size()) {
int next = id + 1;
URI nextUri = uriBuilder.clone().build(next);
Link link = Link.fromUri(nextUri).rel("next").type(MediaType.APPLICATION_XML).build();
links.add(link);
}
if (id - 1 > 0) {
int previous = id - 1;
URI nextUri = uriBuilder.clone().build(previous);
Link link = Link.fromUri(nextUri).rel("previous").type(MediaType.APPLICATION_XML).build();
links.add(link);
}
}
books.add(book);
BookStore bookStore = new BookStore();
bookStore.setLinks(links);
bookStore.setBooks(books);
return bookStore;
}
}
And in the test case, we request the third book, and we can see there are links for the "next" and "previous" books in our in-memory db. We also call getNext() on our BookStore to retrieve the next book in the db, and the result will come with two different links.
public class BookResourceTest {
private static Client client;
@BeforeClass
public static void setUpClass() {
client = ClientBuilder.newClient();
}
@AfterClass
public static void tearDownClass() {
client.close();
}
@Test
public void testBookResourceLinks() throws Exception {
String BASE_URL = "http://localhost:8080/jaxrs-stackoverflow-book/rest/books/3";
WebTarget target = client.target(BASE_URL);
String xmlResult = target.request().accept(MediaType.APPLICATION_XML).get(String.class);
System.out.println(xmlResult);
Unmarshaller unmarshaller = JAXBContext.newInstance(BookStore.class).createUnmarshaller();
BookStore bookStore = (BookStore)unmarshaller.unmarshal(new StringReader(xmlResult));
URI next = bookStore.getNext();
WebTarget nextTarget = client.target(next);
String xmlNextResult = nextTarget.request().accept(MediaType.APPLICATION_XML).get(String.class);
System.out.println(xmlNextResult);
}
}
The result:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<bookstore>
<book author="Author Three" title="Book Three"/>
<link href="http://localhost:8080/jaxrs-stackoverflow-book/rest/books/4" rel="next" type="application/xml"/>
<link href="http://localhost:8080/jaxrs-stackoverflow-book/rest/books/2" rel="previous" type="application/xml"/>
</bookstore>
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<bookstore>
<book author="Author Four" title="Book Four"/>
<link href="http://localhost:8080/jaxrs-stackoverflow-book/rest/books/5" rel="next" type="application/xml"/>
<link href="http://localhost:8080/jaxrs-stackoverflow-book/rest/books/3" rel="previous" type="application/xml"/>
</bookstore>
FYI, I'm using Resteasy 3.0.8 with Wildfly 8.1
UPDATE: Using auto-discovery
So I tried out the reference guide example and I can't reproduce your problem. Not sure your complete environment, but here's what I'm using
- Wildfly 8.1
- Resteasy 3.0.8
- Maven
Here's the code
Application class
@ApplicationPath("/rest")
public class BookApplication extends Application {
@Override
public Set<Class<?>> getClasses() {
Set<Class<?>> classes = new HashSet<>();
classes.add(Bookstore.class);
return classes;
}
}
Resource class
@Path("/books")
@Produces({"application/xml", "application/json"})
public class Bookstore {
@AddLinks
@LinkResource(value = Book.class)
@GET
@Formatted
public Collection<Book> getBooks() {
List<Book> books = new ArrayList<>();
books.add(new Book("Book", "Author"));
return books;
}
}
Book class
@XmlRootElement
@XmlAccessorType(XmlAccessType.NONE)
public class Book {
@XmlAttribute
private String author;
@XmlID @XmlAttribute
private String title;
@XmlElementRef
private RESTServiceDiscovery rest;
public Book() {}
public Book(String title, String author) {
this.title = title;
this.author = author;
}
}
pom.xml (Maybe you are missing some dependencies - Note below resteasy-client and resteasy-servlet-initializer was just for testing)
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.underdogdevs.web</groupId>
<artifactId>jaxrs-stackoverflow-user</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>jaxrs-stackoverflow-user</name>
<properties>
<endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jackson2-provider</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jaxb-provider</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jaxrs</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>jaxrs-api</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-links</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-client</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-servlet-initializer</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-web-api</artifactId>
<version>7.0</version>
<scope>provided</scope>
</dependency>
