Jersey Hello World Example Using JAX-RS Specification

In this tutorial, I will show you how to develop a RESTful hello world web application with Jersey & Maven in Eclipse.  I have used Eclipse Juno to develop all web services. Make sure you have installed Maven plugin in eclipse before you start, you can check this article for help [ How to Install m2eclipse (Maven) Plugin in Eclipse ]

Required

• Eclipse Juno
• JDK 1.6
• Jersey 1.8
• Maven Plugin
• Tomcat 6.0 Server

Steps

• Create a ‘Dynamic Web Project’
• Convert the project into ‘Maven Project’ [ Of course you can also create Maven project directly ]
• Add required dependencies in ‘pom.xml‘
• Change web.xml [ register com.sun.jersey.spi.container.servlet.ServletContainer and add related init-param]
• Run the application

Steps to Create Restful Web Services in Eclipse

Open Eclipse > File > New > Dynamic Web Project

Give the project name and choose ‘Dynamic web module version’ as 2.5 > Finish

Now the project will be created in the work space, right click on the project folder > Configure > Convert to Maven Project

Now it will open Maven POM window, there keep everything as it is, but choose packaging to .war and click Finish

You have created a Maven project, finally your project looks like..

Most probably it will not show any errors, but here Its showing errors. In order to fix this right click on the project > Maven > Update Project > Now you can see the errors gone 🙂

Open pom.xml and add the Maven dependencies just like bellow

Pom.xml

What is pom.xml :
It is an XML file that contains information about the project and configuration details used by Maven to build the project.  Generally at the time of developing any J2EE applications we will search and download the related jar files over the internet and we need to add them in the class path and even in the lib folder as well. But if you can install Maven plugin in your Eclipse, pom.xml will take care of adding these dependencies (‘*.jars) to the project. Your work is to install Maven and  update pom.xml with the required dependencies (jars). However i have already explained, how to install Maven plugin in the Eclipse.

<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>RestPathAnnotationExample</groupId>
<artifactId>RestPathAnnotationExample</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>

<repositories>
       <repository>
         <id>maven2-repository.java.net</id>
          <name>Java.net Repository for Maven</name>
          <url>http://download.java.net/maven/2/</url>
          <layout>default</layout>
       </repository>
</repositories>

<dependencies>
       <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>4.8.2</version>
          <scope>test</scope>
       </dependency>

       <dependency>
          <groupId>com.sun.jersey</groupId>
          <artifactId>jersey-server</artifactId>
          <version>1.8</version>
       </dependency>
</dependencies>

<build>
   <finalName>RestPathAnnotationExample</finalName>
   <plugins>
      <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
             <configuration>
                <compilerVersion>1.5</compilerVersion>
                <source>1.5</source>
                <target>1.5</target>
             </configuration>
       </plugin>
   </plugins>
</build>

</project>

Once you add dependencies [ required libraries ] in pom.xml  > right click on the project > Maven > Update Project > Choose the current project > Ok

HelloWorldService.java

package com.java4s;

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

@Path("/customers")
public class HelloWorldService {

  @GET
  @Produces("text/html")
  public Response getLocalCust() {

           String output = "I am from 'getLocalCust' method";
           return Response.status(200).entity(output).build();
  }

  @GET
  @Path("/nri")
  @Produces("text/html")
  public Response getNriCust() {

            String output = "I am from 'getNriCust' method";
            return Response.status(200).entity(output).build();
  }
}

web.xml

<web-app id="WebApp_ID" version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<display-name>RestPathAnnotationExample</display-name>

<servlet>
    <servlet-name>jersey-serlvet</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>com.java4s</param-value>
       </init-param>
       <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
   <servlet-name>jersey-serlvet</servlet-name>
   <url-pattern>/rest/*</url-pattern>
</servlet-mapping>

</web-app>

<!-- www.Java4s.com -->

Now we are good to run the application, Just right click on the project >Run As > Run on Server > It will open the application URL like
http://localhost:2013/RestPathAnnotationExample/ 

But you need to satisfy the actual URL pattern, i mean change the URL to…

Main application URL:
http://localhost:2013/RestPathAnnotationExample/

Web.xml URL pattern:
/rest

@Path in HelloWorldService.java:
/customers

Final URL should be
http://localhost:2013/RestPathAnnotationExample/rest/customers

Hit with this final URL in your web browser or eclipse browser

It will throw 404 error, because we forgot to add the Maven dependencies in the Deployment Assembly. So how to fix this issue ? just right click on the project > Properties > Deployment Assembly > Add > It will open other window, in that choose ‘Java Build Path Entries‘ click Next..

Choose the Maven Dependencies root and Finish

Now it looks like..

Click Ok > and test the application with URLs
http://localhost:2013/RestPathAnnotationExample/rest/customers

http://localhost:2013/RestPathAnnotationExample/rest/customers/nri  [ Here /nri  is the path i have mentioned in HelloWorldService.java  for getNriCust() method]

You Might Also Like

• Spring Boot + Spring MVC + JSP Hello World Example
• Spring Boot + Maven – Hello World Example Step by Step
• Exception Handling in RESTful Web Services (JAX-RS) with Jersey
• AngularJs Hello World Example
• RESTful Java Client Example Using Jersey Client

::. About the Author .::
		Sivateja Kandula - Java/J2EE Full Stack Developer Founder of Java4s - Get It Yourself, A popular Java/J2EE Programming Blog, Love Java and UI frameworks. You can sign-up for the Email Newsletter for your daily dose of Java tutorials.