Jersey JAX-RS Framework - Step by Step Guide for Developing RESTful web services

Overview

Jersey is a Java framework for developing RESTful web services. It is an implementation of JAX-RS reference.  In addition to JAX-RS , Jersey has its extended APIs that eases the development of restful web services and client development. In this tutorial, I will guide you through the steps to jump-start developing the RESTful web services using the Jersey framework.

Requirements for this tutorial

• Eclipse
• Maven
• Jersey Framework
• Tomcat or any other Servlet container

STEP 1

Open the Eclipse and create an empty Maven web project. Add the following dependencies

  <dependencies>
        <dependency>
            <groupId>javax.ws.rs</groupId>
            <artifactId>javax.ws.rs-api</artifactId>
            <version>${jaxrs.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.containers</groupId>
            <artifactId>jersey-container-servlet</artifactId>
            <version>${jersey2.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.core</groupId>
            <artifactId>jersey-server</artifactId>
            <version>${jersey2.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.core</groupId>
            <artifactId>jersey-client</artifactId>
            <version>${jersey2.version}</version>
        </dependency>
        <dependency>
          <groupId>org.glassfish.jersey.inject</groupId>
          <artifactId>jersey-hk2</artifactId>
          <version>${jersey2.version}</version>
        </dependency>  
   </dependencies>

STEP 2

Create a class with the following code

package com.techieshah;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.QueryParam;
import com.techieshah.domainmodel.BlogPost;

/*Author: https://techieshah.blogspot.com*/
@Path("/")
public class JerseyExample {
  
    @GET
    public BlogPost get(@QueryParam("id") Integer id){
       
        for(BlogPost blogPost : BlogPostRepository.blogPosts) {
            if(blogPost.id == id) {
                return blogPost;
            }
        }
        return null;
    }
    
    @POST
    public String post( BlogPost blogPost){
        BlogPostRepository.blogPosts.add(blogPost);
        return "Blog Post saved successfully";
    }
    
    @PUT
    public String put(BlogPost updatedBlogPost) {
        for(BlogPost blogPost : BlogPostRepository.blogPosts) {
            if(blogPost.id == updatedBlogPost.id) {
               blogPost.name = updatedBlogPost.name;
               blogPost.tag = updatedBlogPost.tag;
               blogPost.content = updatedBlogPost.content;
            }
        }
        return "Blog Post updated successfully";
    }
    
    @DELETE
    public String delete(@QueryParam("id") Integer id){
        
        for(BlogPost blogPost : BlogPostRepository.blogPosts) {
            if(blogPost.id == id) {
                BlogPostRepository.blogPosts.remove( blogPost );
                break;
            }
        }
        return "Blog Post deleted successfully";
    }

}


@Path("/")

This specifies the URL path for this resource.

@QueryParam

This is used to specify the Query parameters in the URL

The following annotations are used to map the class functions against the corresponding HTTP methods

@GET (for selection), @POST (for insert) , @PUT (for update) and @DELETE (for delete)

STEP 3

Modify the web.xml 

<servlet>
<servlet-name>JerseyService</servlet-name>
<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
<init-param>
<param-name>jersey.config.server.provider.packages</param-name>
<param-value>com.techieshah</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>JerseyService </servlet-name>
<url-pattern>/api/*</url-pattern>

</servlet-mapping>

Now our web services are ready for testing. We can use any Rest client to test it.

Request 

GET  http://localhost:9080/jerseywsexample/api?id=1

Response

<blogPost> <id>1</id> <name>spring framework</name> <tag>ws</tag> <content>first example of rest web services</content> </blogPost>

Similarly, we can test the remaining methods i.e. POST, PUT and DELETE.

Complete source code can be downloaded from Jersey JAX-RS Example .