[英]Inserting links into RESTEasy XML results via JAXB
我想通過RESTeasy / JAXB將鏈接插入XML。 我試圖使用我的代碼的文檔 ,但這不起作用,所以我只是在文檔中編寫給定的示例:它仍然不起作用,我不知道為什么。
要在我的JBoss RESTEasy API中實現HATEOAS原則,我必須在我的JAXB XML結果中插入鏈接,以便客戶端可以瀏覽API。
我現在正試圖了解如何做到這一點,但我不確定文檔是否充滿錯誤,或者我只是無法理解示例和解釋:
據我了解,你必須使用@AddLinks
來聲明結果應該插入鏈接。 然后我必須使用@LinkResource
再次 (!?) 冗余地執行此操作,並且“ 有時 ”指定URI構建過程應該來自哪個類(例如@LinkResource(value = car.class)
)。 然后我必須在實體類中添加一個RESTServiceDiscovery
,用@XmlElementRef
注釋它......但在示例中,在聲明(!?)之后, RESTServiceDiscovery
根本沒有被使用。
我真的很困惑如何使用所有這些,但當然我自己嘗試了很多代碼,讓它工作。
以下代碼就像文檔示例:
BookController.java
import java.util.ArrayList;
import java.util.Collection;
import javax.ws.rs.Consumes;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import org.jboss.resteasy.links.AddLinks;
import org.jboss.resteasy.links.LinkResource;
import com.gasx.extsys.datamodel.vo.kplan.Book;
@Path("/")
@Consumes({ "application/xml", "application/json" })
@Produces({ "application/xml", "application/json" })
public class BookController {
@AddLinks
@LinkResource(value = Book.class)
@GET
@Path("books")
public Collection<Book> getBooks() {
ArrayList<Book> res = new ArrayList<Book>();
res.add(new Book("Robert", "WhySOIsGreat"));
res.add(new Book("Robert", "JavaUltimateGuide"));
res.add(new Book("Not Robert", "ThisIsSparta!"));
return res;
};
@AddLinks
@LinkResource
@GET
@Path("book/{id}")
public Book getBook(@PathParam("id") String id) {
return new Book("Robert", "WhyIloveJAVA");
};
}
Book.java :
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElementRef;
import javax.xml.bind.annotation.XmlID;
import javax.xml.bind.annotation.XmlRootElement;
import org.jboss.resteasy.links.RESTServiceDiscovery;
@XmlRootElement
@XmlAccessorType(XmlAccessType.NONE)
public class Book {
@XmlAttribute
private String author = "startAuthor";
@XmlID
@XmlAttribute
private String title = "startTitle";
@XmlElementRef
private RESTServiceDiscovery rest;
public Book() {
}
public Book(String author, String title) {
this.author = author;
this.title = title;
}
}
現在在books
或book/1
上調用GET會拋出此錯誤:
2014-09-25 11:30:36,188 WARN [http-/0.0.0.0:8080-1] (org.jboss.resteasy.core.SynchronousDispatcher:135) # Failed executing GET /book/1: org.jboss.resteasy.plugins.providers.jaxb.JAXBMarshalException: com.sun.xml.bind.v2.runtime.IllegalAnnotationsException: 1 counts of IllegalAnnotationExceptions
XmlElementRef points to a non-existent class.
我不知道這到底是怎么工作的,所以我試着用以下的Book.java代碼手動添加的URI:
import java.net.URI;
public Book(String author, String title) {
this.author = author;
this.title = title;
URI uri = URI.create("books/" + title);
rest = new RESTServiceDiscovery();
rest.addLink(uri, "self");
}
但這仍然會引發同樣的錯誤。
我不太熟悉鏈接注入,但添加鏈接的一種簡單方法是將javax.ws.rs.core.Link
嵌入到JAXB實體類中。 它帶有一個內置的XmlAdapter, Link.JaxbAdapter
,它允許Link
類型由JAXB編組Link.JaxbAdapter
。 例如,您有一個BookStore
類,其中包含一系列Books
。 它還將具有Link
,您可以從中控制導航案例。
@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;
}
}
Book
類只是一個常規的根元素JAXB類
@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;
}
}
在BookResource
類中,我們基本上可以根據您想要表示的鏈接所需的邏輯按需添加鏈接。 在下面的示例中,有一個內存數據庫(此類僅用作有狀態單例類)的書籍,我為其添加了五本書,並增加了ID。 當請求進入時,將向返回的BookStore
添加一個或兩個鏈接。 根據請求的ID,我們將添加“下一個”和/或之前的“鏈接。鏈接將具有我們從BookStore
類引用的rel
。
@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;
}
}
在測試用例中,我們請求第三本書,我們可以看到內存數據庫中有“下一頁”和“上一頁”書籍的鏈接。 我們還在BookStore
上調用getNext()
來檢索db中的下一本書,結果將帶有兩個不同的鏈接。
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);
}
}
結果:
<?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>
僅供參考,我正在使用Resteasy 3.0.8和Wildfly 8.1
所以我嘗試了參考指南示例,我無法重現您的問題。 不確定你的完整環境,但這是我正在使用的
這是代碼
應用類
@ApplicationPath("/rest")
public class BookApplication extends Application {
@Override
public Set<Class<?>> getClasses() {
Set<Class<?>> classes = new HashSet<>();
classes.add(Bookstore.class);
return classes;
}
}
資源類
@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;
}
}
預訂課程
@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(也許你缺少一些依賴項 - 注意下面的resteasy-client和resteasy-servlet-initializer僅用於測試)
<?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>${project.build.directory}/endorsed</endorsed.dir>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jackson2-provider</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jaxb-provider</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jaxrs</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>jaxrs-api</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-links</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-client</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-servlet-initializer</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-web-api</artifactId>
<version>7.0</version>
<scope>provided</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.wildfly.bom</groupId>
<artifactId>jboss-javaee-7.0-with-resteasy</artifactId>
<version>8.1.0.Final</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.wildfly.bom</groupId>
<artifactId>jboss-javaee-7.0-with-tools</artifactId>
<version>8.1.0.Final</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
<compilerArguments>
<endorseddirs>${endorsed.dir}</endorseddirs>
</compilerArguments>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.3</version>
<configuration>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.6</version>
<executions>
<execution>
<phase>validate</phase>
<goals>
<goal>copy</goal>
</goals>
<configuration>
<outputDirectory>${endorsed.dir}</outputDirectory>
<silent>true</silent>
<artifactItems>
<artifactItem>
<groupId>javax</groupId>
<artifactId>javaee-endorsed-api</artifactId>
<version>7.0</version>
<type>jar</type>
</artifactItem>
</artifactItems>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
public class BookTest {
private static Client client;
@BeforeClass
public static void setUpClass() {
client = ClientBuilder.newClient();
}
@AfterClass
public static void tearDownClass() {
client.close();
}
@Test
public void testBookLink() {
String BASE_URL
= "http://localhost:8080/jaxrs-stackoverflow-user/rest/books";
WebTarget target = client.target(BASE_URL);
String result = target.request()
.accept(MediaType.APPLICATION_XML).get(String.class);
System.out.println(result);
}
}
結果
Running jaxrs.book.test.BookTest
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<collection xmlns:atom="http://www.w3.org/2005/Atom">
<book author="Author" title="Book">
<atom:link rel="list" href="http://localhost:8080/jaxrs-stackoverflow-user/rest/books"/>
</book>
</collection>
使用
@AddLinks
注釋JAX-RS方法,以指示您希望在響應實體中注入Atom鏈接。
這是為了表明該方法將使用鏈接注入。
使用
@LinkResource
注釋您希望Atom鏈接的JAX-RS方法,以便RESTEasy知道要為哪些資源創建哪些鏈接。
這允許您自定義注入的鏈接和實體。 8.2.4。 指定哪些JAX-RS方法與哪些資源的關聯更深入。
將RESTServiceDiscovery字段添加到要注入Atom鏈接的資源類中。
“注入”意味着框架將為您實例化,因此您永遠不必自己明確地執行此操作(正如您嘗試的那樣)。 也許對依賴注入和控制反轉(IoC)進行一些研究
祝好運。 希望這一切都有幫助。
我只想補充一點,如果你想在JSON中添加你的ATOM鏈接,你需要禁用/排除所有的jackson提供者。 即在WildFly 8.x中創建一個META-INF / jboss-deployment-structure.xml,其中包含以下內容:
<jboss-deployment-structure>
<deployment>
<exclusions>
<module name="org.jboss.resteasy.resteasy-jackson-provider" />
<module name="org.jboss.resteasy.resteasy-jackson2-provider" />
</exclusions>
<dependencies>
<module name="org.jboss.resteasy.resteasy-jettison-provider" />
</dependencies>
</deployment>
</jboss-deployment-structure>
這樣,jettison提供程序將正確創建包含ATOM鏈接的JSON表示
希望這可以幫助 ;)
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