Jersey hello world example

Jersey, reference implementation to develope RESTful web service based on the JAX-RS (JSR 311) specification.

In this tutorial, we show you how to develop a simple hello world REST web application with Jersey.

Technologies and Tools used in this article:

1. Jersey 1.8
2. JDK 1.6
3. Tomcat 6.0
4. Maven 3.0.3
5. Eclipse 3.6

1. Directory Structure

This is the final web project structure of this tutorial.

2. Standard Web Project

Create a standard Maven web project structure.

mvn archetype:generate -DgroupId=com.mkyong.rest -DartifactId=RESTfulExample

                -DarchetypeArtifactId=maven-archetype-webapp -DinteractiveMode=false

3. Project Dependencies

Jersey is published in Java.net Maven repository. To develop Jersey REST application , just declares “jersey-server” in Maven pom.xml.

File : pom.xml

<project ...>

                <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>com.sun.jersey</groupId>

                                                <artifactId>jersey-server</artifactId>

                                                <version>1.8</version>

                                </dependency>

                </dependencies>

               

</project>

4. REST Service

Simple REST service with Jersey.

package com.mkyong.rest;

import javax.ws.rs.GET;

import javax.ws.rs.Path;

import javax.ws.rs.PathParam;

import javax.ws.rs.core.Response;

@Path("/hello")

public class HelloWorldService {

                @GET

                @Path("/{param}")

                public Response getMsg(@PathParam("param") String msg) {

                                String output = "Jersey say : " + msg;

                                return Response.status(200).entity(output).build();

                }

}

5. web.xml

In web.xml, register “com.sun.jersey.spi.container.servlet.ServletContainer“, and puts your Jersey service folder under “init-param“, “com.sun.jersey.config.property.packages“.

File : 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>Restful Web Application</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.mkyong.rest</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>

6. Demo

In this example, web request from “projectURL/rest/hello/” will match to “HelloWorldService“, via @Path("/hello").

And the “{any values}” from “projectURL/rest/hello/{any values}” will match to parameter annotated with @PathParam.

URL : http://localhost:8080/RESTfulExample/rest/hello/mkyong