My Technotes: REST with Java (JAX-RS) using Jersey

RESTful web services with Java (Jersey / JAX-RS)

This tutorial explains how to develop RESTful web services in Java with the JAX-RS reference implementation Jersey.
In this tutorial Eclipse 4.4 (Luna), Java 1.6, Tomcat 6.0 and JAX-RS 2.0 (with Jersey 2.11) is used.

Table of Contents

1. REST - Representational State Transfer

1.1. What is REST?
1.2. HTTP methods
1.3. RESTFul web services

2. JAX-RS with Jersey

2.1. JAX-RS
2.2. JAX-RS
2.3. JAX-RS annotations

3. Jersey

4. Web container

5. Prerequisites

6. Create your first RESTful Webservice

6.1. Create a project with Jersey libraries
6.2. Java Class
6.3. Define Jersey Servlet dispatcher
6.4. Run your rest service

7. Create a client

8. RESTful web services and JAXB

8.1. Create project
8.2. Create a client

9. CRUD RESTful webservice

9.1. Project
9.2. Create a simple HTML form
9.3. Rest Service
9.4. Run
9.5. Create a client
9.6. Using the REST service via HTML page
9.7. Using the rest service via X

10. Support this website

10.1. Thank you
10.2. Questions and Discussion

11. Links and Literature

11.1. Source Code
11.2. Rest Resources
11.3. vogella Resources

1. REST - Representational State Transfer

1.1. What is REST?

REST is an architectural style which is based on web-standards and the HTTP protocol. REST was first described by Roy Fielding in 2000.
In a REST based architecture everything is a resource. A resource is accessed via a common interface based on the HTTP standard methods.
In a REST based architecture you typically have a REST server which provides access to the resources and a REST client which accesses and modifies the REST resources.
Every resource should support the HTTP common operations. Resources are identified by global IDs (which are typically URIs).
REST allows that resources have different representations, e.g., text, XML, JSON etc. The REST client can ask for a specific representation via the HTTP protocol (content negotiation).

1.2. HTTP methods

The PUT, GET, POST and DELETE methods are typical used in REST based architectures.
The following table gives an explanation of these operations.

GET defines a reading access of the resource without side-effects. The resource is never changed via a GET request, e.g., the request has no side effects (idempotent).
PUT creates a new resource. It must also be idempotent.
DELETE removes the resources. The operations are idempotent. They can get repeated without leading to different results.
POST updates an existing resource or creates a new resource.

1.3. RESTFul web services

A RESTFul web services are based on HTTP methods and the concept of REST. A RESTFul web service typically defines the base URI for the services, the supported MIME-types (XML, text, JSON, user-defined, ...) and the set of operations (POST, GET, PUT, DELETE) which are supported.

2. JAX-RS with Jersey

2.1. JAX-RS

Java defines REST support via the Java Specification Request (JSR) 311. This specification is called JAX-RS (The Java API for RESTful Web Services). JAX-RS uses annotations to define the REST relevance of Java classes.

2.2. JAX-RS

Jersey is the reference implementation for the JSR 311 specification.
The Jersey implementation provides a library to implement Restful webservices in a Java servlet container.
On the server side Jersey provides a servlet implementation which scans predefined classes to identify RESTful resources. In your web.xml configuration file your register this servlet for your web application.
The Jersey implementation also provides a client library to communicate with a RESTful webservice.
The base URL of this servlet is:

http://your_domain:port/display-name/url-pattern/path_from_rest_class

This servlet analyzes the incoming HTTP request and selects the correct class and method to respond to this request. This selection is based on annotations in the class and methods.
A REST web application consists, therefore, out of data classes (resources) and services. These two types are typically maintained in different packages as the Jersey servlet will be instructed via the web.xml to scan certain packages for data classes.
JAX-RS supports the creation of XML and JSON via the Java Architecture for XML Binding (JAXB).
JAXB is described in the JAXB Tutorial .

2.3. JAX-RS annotations

The most important annotations in JAX-RS are listed in the following table.

Table 1. JAX-RS annotations

Annotation	Description
@PATH(your_path)	Sets the path to base URL + /your_path. The base URL is based on your application name, the servlet and the URL pattern from the `web.xml` configuration file.
@POST	Indicates that the following method will answer to an HTTP POST request.
@GET	Indicates that the following method will answer to an HTTP GET request.
@PUT	Indicates that the following method will answer to an HTTP PUT request.
@DELETE	Indicates that the following method will answer to an HTTP DELETE request.
@Produces(MediaType.TEXT_PLAIN[, more-types])	@Produces defines which MIME type is delivered by a method annotated with @GET. In the example text ("text/plain") is produced. Other examples would be "application/xml" or "application/json".
@Consumes(type[, more-types])	@Consumes defines which MIME type is consumed by this method.
@PathParam	Used to inject values from the URL into a method parameter. This way you inject, for example, the ID of a resource into the method to get the correct object.

The complete path to a resource is based on the base URL and the @PATh annotation in your class.

http://your_domain:port/display-name/url-pattern/path_from_rest_class

3. Jersey

Download the Jersey distribution as zip file from the Jersey download site.
The zip contains the Jersey implementation JAR and its core dependencies. It does not provide dependencies for third party JARs beyond those for JSON support and JavaDoc.

4. Web container

For this tutorial you can use any web container, for example Tomcat or the Google App Engine.
If you want to use Tomcat as servlet container please see Eclipse WTP and Apache Tomcat for instructions on how to install and use Eclipse WTP and Apache Tomcat.
Alternative you could also use the Google App Engine for running the server part of the following REST examples. If you use the Google App Engine, you do not have to install and configure Tomcat.

Tip

If you are using GAE/J, you have to create App Engine projects instead of Dynamic Web Project. The following description is based on Apache Tomcat.

5. Prerequisites

The following description assumes that you are familiar with creating web applications in Eclipse. See Eclipse WTP development for an introduction into creating web applications with Eclipse.

6. Create your first RESTful Webservice

6.1. Create a project with Jersey libraries

Create a new Dynamic Web Project called com.vogella.jersey.first.

Ensure that you create the web.xml deployment descriptor.

Copy all JARs from your Jersey download into the WEB-INF/lib folder.

6.2. Java Class

Create the following class.

package com.vogella.jersey.first;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

// Plain old Java Object it does not extend as class or implements 
// an interface

// The class registers its methods for the HTTP GET request using the @GET annotation. 
// Using the @Produces annotation, it defines that it can deliver several MIME types,
// text, XML and HTML. 

// The browser requests per default the HTML MIME type.

//Sets the path to base URL + /hello
@Path("/hello")
public class Hello {

  // This method is called if TEXT_PLAIN is request
  @GET
  @Produces(MediaType.TEXT_PLAIN)
  public String sayPlainTextHello() {
    return "Hello Jersey";
  }

  // This method is called if XML is request
  @GET
  @Produces(MediaType.TEXT_XML)
  public String sayXMLHello() {
    return "<?xml version=\"1.0\"?>" + "<hello> Hello Jersey" + "</hello>";
  }

  // This method is called if HTML is request
  @GET
  @Produces(MediaType.TEXT_HTML)
  public String sayHtmlHello() {
    return "<html> " + "<title>" + "Hello Jersey" + "</title>"
        + "<body><h1>" + "Hello Jersey" + "</body></h1>" + "</html> ";
  }

}

This class register itself as a get resource via the @GET annotation. Via the @Produces annotation it defines that it delivers the text and the HTML MIME types. It also defines via the @Path annotation that its service is available under the hello URL.
The browser will always request the HTML MIME type. To see the text version, you can use tool like curl.

6.3. Define Jersey Servlet dispatcher

You need to register Jersey as the servlet dispatcher for REST requests. Open the file web.xml and modify it to the following.

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>com.vogella.jersey.first</display-name>
 <servlet>
    <servlet-name>Jersey REST Service</servlet-name>
    <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
     <!-- Register resources and providers under com.vogella.jersey.first package. -->
    <init-param>
        <param-name>jersey.config.server.provider.packages</param-name>
        <param-value>com.vogella.jersey.first</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>Jersey REST Service</servlet-name>
    <url-pattern>/rest/*</url-pattern>
  </servlet-mapping>
</web-app>

The parameter com.sun.jersey.config.property.package defines in which package Jersey will look for the web service classes. This property must point to your resources classes. The URL pattern defines the part of the base URL your application will be placed.

6.4. Run your rest service

Run you web application in Eclipse. See Eclipse WTP for details on how to run dynamic web applications.
You should be able to access your resources under the following URL: http://localhost:8080/com.vogella.jersey.first/rest/hello

This name is derived from the "display-name" defined in the web.xml file, augmented with the servlet-mapping URL-pattern and the hello @Path annotation from your class file. You should get the message "Hello Jersey".
The browser requests the HTML representation of your resource. In the next chapter we are going to write a client which will read the XML representation.

7. Create a client

Jersey contains a REST client library which can be used for testing or to build a real client in Java. Alternatively, you could use Apache HttpClient to create a client.
Create a new Java project de.vogella.jersey.first.client and add the Jersey JARs to the project and the project build path. Create the following test class.

package de.vogella.jersey.first.client;

import java.net.URI;

import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.UriBuilder;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;

public class Test {
  public static void main(String[] args) {
    ClientConfig config = new DefaultClientConfig();
    Client client = Client.create(config);
    WebResource service = client.resource(getBaseURI());
    // Fluent interfaces
    System.out.println(service.path("rest").path("hello").accept(MediaType.TEXT_PLAIN).get(ClientResponse.class).toString());
    // Get plain text
    System.out.println(service.path("rest").path("hello").accept(MediaType.TEXT_PLAIN).get(String.class));
    // Get XML
    System.out.println(service.path("rest").path("hello").accept(MediaType.TEXT_XML).get(String.class));
    // The HTML
    System.out.println(service.path("rest").path("hello").accept(MediaType.TEXT_HTML).get(String.class));

  }

  private static URI getBaseURI() {
    return UriBuilder.fromUri("http://localhost:8080/de.vogella.jersey.first").build();
  }

}

8. RESTful web services and JAXB

JAX-RS supports the automatic creation of XML and JSON via JAXB. For an introduction into XML please see Java and XML - Tutorial. For an introduction into JAXB please see JAXB. You can continue this tutorial without reading these tutorials, but they contain more background information.

8.1. Create project

Create a new Dynamic Web Project called de.vogella.jersey.jaxb and copy all Jersey JARs into the WEB-INF/lib folder.
Create your domain class.

package de.vogella.jersey.jaxb.model;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
// JAX-RS supports an automatic mapping from JAXB annotated class to XML and JSON
// Isn't that cool?
public class Todo {
  private String summary;
  private String description;
  public String getSummary() {
    return summary;
  }
  public void setSummary(String summary) {
    this.summary = summary;
  }
  public String getDescription() {
    return description;
  }
  public void setDescription(String description) {
    this.description = description;
  }

  
}

Create the following resource class. This class simply returns an instance of the Todo class.

package de.vogella.jersey.jaxb;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

import de.vogella.jersey.jaxb.model.Todo;

@Path("/todo")
public class TodoResource {
  // This method is called if XMLis request
  @GET
  @Produces({ MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON })
  public Todo getXML() {
    Todo todo = new Todo();
    todo.setSummary("This is my first todo");
    todo.setDescription("This is my first todo");
    return todo;
  }
  
  // This can be used to test the integration with the browser
  @GET
  @Produces({ MediaType.TEXT_XML })
  public Todo getHTML() {
    Todo todo = new Todo();
    todo.setSummary("This is my first todo");
    todo.setDescription("This is my first todo");
    return todo;
  }

}

Change web.xml to the following.

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
  id="WebApp_ID" version="2.5">
  <display-name>de.vogella.jersey.jaxb</display-name>
  <servlet>
    <servlet-name>Jersey REST Service</servlet-name>
    <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
    <init-param>
      <param-name>com.sun.jersey.config.property.packages</param-name>
      <param-value>de.vogella.jersey.jaxb</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>Jersey REST Service</servlet-name>
    <url-pattern>/rest/*</url-pattern>
  </servlet-mapping>
</web-app>

Run you web application in Eclipse and validate that you can access your service. Your application should be available under the following URL.

http://localhost:8080/de.vogella.jersey.jaxb/rest/todo

8.2. Create a client

Create a new Java project de.vogella.jersey.jaxb.client and add the Jersey JARs to the project and the project build path. Create the following test class.

package de.vogella.jersey.jaxb.client;


import java.net.URI;

import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.UriBuilder;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;

public class Test {
  public static void main(String[] args) {
    ClientConfig config = new DefaultClientConfig();
    Client client = Client.create(config);
    WebResource service = client.resource(getBaseURI());
    // Get XML
    System.out.println(service.path("rest").path("todo").accept(MediaType.TEXT_XML).get(String.class));
    // Get XML for application
    System.out.println(service.path("rest").path("todo").accept(MediaType.APPLICATION_JSON).get(String.class));
    // Get JSON for application
    System.out.println(service.path("rest").path("todo").accept(MediaType.APPLICATION_XML).get(String.class));
  }

  private static URI getBaseURI() {
    return UriBuilder.fromUri("http://localhost:8080/de.vogella.jersey.jaxb").build();
  }

}

9. CRUD RESTful webservice

This section creates a CRUD (Create, Read, Update, Delete) restful web service. It will allow to maintain a list of TODOs in your web application via HTTP calls.

9.1. Project

Create a new dynamic project called de.vogella.jersey.todo and add the Jersey libs. Change the web.xml file to the following.

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>de.vogella.jersey.todo</display-name>
  <servlet>
    <servlet-name>Jersey REST Service</servlet-name>
    <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
    <init-param>
      <param-name>com.sun.jersey.config.property.packages</param-name>
      <param-value>de.vogella.jersey.todo.resources</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>Jersey REST Service</servlet-name>
    <url-pattern>/rest/*</url-pattern>
  </servlet-mapping>
</web-app>

Create the following data model and a Singleton which serves as the data provider for the model. We use the implementation based on an enumeration. Please see the link for details. The Todo class is annotated with a JAXB annotation. See Java and XML to learn about JAXB.

package de.vogella.jersey.todo.model;


import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Todo {
  private String id;
  private String summary;
  private String description;
  
  public Todo(){
    
  }
  public Todo (String id, String summary){
    this.id = id;
    this.summary = summary;
  }
  public String getId() {
    return id;
  }
  public void setId(String id) {
    this.id = id;
  }
  public String getSummary() {
    return summary;
  }
  public void setSummary(String summary) {
    this.summary = summary;
  }
  public String getDescription() {
    return description;
  }
  public void setDescription(String description) {
    this.description = description;
  }
  
  
}

package de.vogella.jersey.todo.dao;

import java.util.HashMap;
import java.util.Map;

import de.vogella.jersey.todo.model.Todo;

public enum TodoDao {
  instance;
  
  private Map<String, Todo> contentProvider = new HashMap<String, Todo>();
  
  private TodoDao() {
    
    Todo todo = new Todo("1", "Learn REST");
    todo.setDescription("Read http://www.vogella.com/tutorials/REST/article.html");
    contentProvider.put("1", todo);
    todo = new Todo("2", "Do something");
    todo.setDescription("Read complete http://www.vogella.com");
    contentProvider.put("2", todo);
    
  }
  public Map<String, Todo> getModel(){
    return contentProvider;
  }
  
}

9.2. Create a simple HTML form

The REST service can be used via HTML forms. The following HTML form will allow to post new data to the service. Create the following page called create_todo.html in the WebContent folder.

<!DOCTYPE html>
<html>
 <head>
  <title>Form to create a new resource</title>
 </head>
<body>
  <form action="../de.vogella.jersey.todo/rest/todos" method="POST">
  <label for="id">ID</label>
  <input name="id" />
  <br/>
  <label for="summary">Summary</label>
  <input name="summary" />
  <br/>
  Description:
  <TEXTAREA NAME="description" COLS=40 ROWS=6></TEXTAREA>
  <br/>
  <input type="submit" value="Submit" />
  </form>
</body>
</html>

9.3. Rest Service

Create the following classes which will be used as REST resources.

package de.vogella.jersey.todo.resources;

import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.PUT;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.UriInfo;
import javax.xml.bind.JAXBElement;

import de.vogella.jersey.todo.dao.TodoDao;
import de.vogella.jersey.todo.model.Todo;

public class TodoResource {
  @Context
  UriInfo uriInfo;
  @Context
  Request request;
  String id;
  public TodoResource(UriInfo uriInfo, Request request, String id) {
    this.uriInfo = uriInfo;
    this.request = request;
    this.id = id;
  }
  
  //Application integration     
  @GET
  @Produces({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})
  public Todo getTodo() {
    Todo todo = TodoDao.instance.getModel().get(id);
    if(todo==null)
      throw new RuntimeException("Get: Todo with " + id +  " not found");
    return todo;
  }
  
  // for the browser
  @GET
  @Produces(MediaType.TEXT_XML)
  public Todo getTodoHTML() {
    Todo todo = TodoDao.instance.getModel().get(id);
    if(todo==null)
      throw new RuntimeException("Get: Todo with " + id +  " not found");
    return todo;
  }
  
  @PUT
  @Consumes(MediaType.APPLICATION_XML)
  public Response putTodo(JAXBElement<Todo> todo) {
    Todo c = todo.getValue();
    return putAndGetResponse(c);
  }
  
  @DELETE
  public void deleteTodo() {
    Todo c = TodoDao.instance.getModel().remove(id);
    if(c==null)
      throw new RuntimeException("Delete: Todo with " + id +  " not found");
  }
  
  private Response putAndGetResponse(Todo todo) {
    Response res;
    if(TodoDao.instance.getModel().containsKey(todo.getId())) {
      res = Response.noContent().build();
    } else {
      res = Response.created(uriInfo.getAbsolutePath()).build();
    }
    TodoDao.instance.getModel().put(todo.getId(), todo);
    return res;
  }
  
  

}

package de.vogella.jersey.todo.resources;


import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.Consumes;
import javax.ws.rs.FormParam;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.UriInfo;

import de.vogella.jersey.todo.dao.TodoDao;
import de.vogella.jersey.todo.model.Todo;


// Will map the resource to the URL todos
@Path("/todos")
public class TodosResource {

  // Allows to insert contextual objects into the class, 
  // e.g. ServletContext, Request, Response, UriInfo
  @Context
  UriInfo uriInfo;
  @Context
  Request request;


  // Return the list of todos to the user in the browser
  @GET
  @Produces(MediaType.TEXT_XML)
  public List<Todo> getTodosBrowser() {
    List<Todo> todos = new ArrayList<Todo>();
    todos.addAll(TodoDao.instance.getModel().values());
    return todos; 
  }
  
  // Return the list of todos for applications
  @GET
  @Produces({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})
  public List<Todo> getTodos() {
    List<Todo> todos = new ArrayList<Todo>();
    todos.addAll(TodoDao.instance.getModel().values());
    return todos; 
  }
  
  
  // retuns the number of todos
  // use http://localhost:8080/de.vogella.jersey.todo/rest/todos/count
  // to get the total number of records
  @GET
  @Path("count")
  @Produces(MediaType.TEXT_PLAIN)
  public String getCount() {
    int count = TodoDao.instance.getModel().size();
    return String.valueOf(count);
  }
  
  @POST
  @Produces(MediaType.TEXT_HTML)
  @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
  public void newTodo(@FormParam("id") String id,
      @FormParam("summary") String summary,
      @FormParam("description") String description,
      @Context HttpServletResponse servletResponse) throws IOException {
    Todo todo = new Todo(id,summary);
    if (description!=null){
      todo.setDescription(description);
    }
    TodoDao.instance.getModel().put(id, todo);
    
    servletResponse.sendRedirect("../create_todo.html");
  }
  
  
  // Defines that the next path parameter after todos is
  // treated as a parameter and passed to the TodoResources
  // Allows to type http://localhost:8080/de.vogella.jersey.todo/rest/todos/1
  // 1 will be treaded as parameter todo and passed to TodoResource
  @Path("{todo}")
  public TodoResource getTodo(@PathParam("todo") String id) {
    return new TodoResource(uriInfo, request, id);
  }
  
}

This TodosResource uses the @PathParam annotation to define that the id is inserted as parameter.

9.4. Run

Run you web application in Eclipse and test the availability of your REST service under: http://localhost:8080/de.vogella.jersey.todo/rest/todos. You should see the XML representation of your TODO items.

To see the count of TODO items use http://localhost:8080/de.vogella.jersey.todo/rest/todos/count to see an exiting TODO use "http://localhost:8080/de.vogella.jersey.todo/rest/todos/{id}", e.g., http://localhost:8080/de.vogella.jersey.todo/rest/todos/1 to see the TODO with ID 1. We currently have only TODOs with the ids 1 and 2, all other requests will result in an HTTP error code.
Please note that with the browser you can only issue HTTP GET requests. The next chapter will use the Jersey client libraries to issue get, post and delete.

9.5. Create a client

Create a new Java project called de.vogella.jersey.todo.client. Create a lib folder and place all Jersey libraries in this folder. Add the JARs to the classpath of the project.
Create the following class.

package de.vogella.jersey.todo.client;

import java.net.URI;

import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.UriBuilder;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;
import com.sun.jersey.api.representation.Form;

import de.vogella.jersey.todo.model.Todo;

public class Tester {
  public static void main(String[] args) {
    ClientConfig config = new DefaultClientConfig();
    Client client = Client.create(config);
    WebResource service = client.resource(getBaseURI());
    // create one todo
    Todo todo = new Todo("3", "Blabla");
    ClientResponse response = service.path("rest").path("todos")
        .path(todo.getId()).accept(MediaType.APPLICATION_XML)
        .put(ClientResponse.class, todo);
    // Return code should be 201 == created resource
    System.out.println(response.getStatus());
    // Get the Todos
    System.out.println(service.path("rest").path("todos")
        .accept(MediaType.TEXT_XML).get(String.class));
    // Get JSON for application
    System.out.println(service.path("rest").path("todos")
        .accept(MediaType.APPLICATION_JSON).get(String.class));
    // Get XML for application
    System.out.println(service.path("rest").path("todos")
        .accept(MediaType.APPLICATION_XML).get(String.class));

    // Get the Todo with id 1
    System.out.println(service.path("rest").path("todos/1")
        .accept(MediaType.APPLICATION_XML).get(String.class));
    // get Todo with id 1
    service.path("rest").path("todos/1").delete();
    // Get the all todos, id 1 should be deleted
    System.out.println(service.path("rest").path("todos")
        .accept(MediaType.APPLICATION_XML).get(String.class));

    // create a Todo
    Form form = new Form();
    form.add("id", "4");
    form.add("summary", "Demonstration of the client lib for forms");
    response = service.path("rest").path("todos")
        .type(MediaType.APPLICATION_FORM_URLENCODED)
        .post(ClientResponse.class, form);
    System.out.println("Form response " + response.getEntity(String.class));
    // Get the all todos, id 4 should be created
    System.out.println(service.path("rest").path("todos")
        .accept(MediaType.APPLICATION_XML).get(String.class));

  }

  private static URI getBaseURI() {
    return UriBuilder.fromUri("http://localhost:8080/de.vogella.jersey.todo").build();
  }
}

9.6. Using the REST service via HTML page

The above example contains a form which calls a post method of your rest service.

9.7. Using the rest service via X

Usually every programming language provides libraries for creating HTTP get, post, put and delete requests. For Java this is the project Apache HttpClient.

10. Support this website

This tutorial is Open Content under the CC BY-NC-SA 3.0 DE license. Source code in this tutorial is distributed under the Eclipse Public License. See the vogella License page for details on the terms of reuse.
Writing and updating these tutorials is a lot of work. If this free community service was helpful, you can support the cause by giving a tip as well as reporting typos and factual errors.

My Technotes

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Monday, September 8, 2014

REST with Java (JAX-RS) using Jersey - Tutorial