Jersey Rest Hello World Example

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In this example, we will learn how to develop a simple Jersey Rest hello world example.

JAX-RS Specification is the Java API for RESTful web services. Jersey is the open source reference implementation of Java JAX-RS specification. It provides a Java library using which we can easily create RESTful web services in Java platform. JAX-RS / Jersey supports JAXB based XML bindings as well.

Technologies and tools used

• Jersey 2.27
• JDK 1.8
• Tomcat 8.5
• Maven 3.0.3
• Eclipse Neon

In this tutorial, we have used the latest Jersey version 2.27 with JDK 8. Deployment of a JAX-RS application using @ApplicationPath with Servlet 3.0 ( use @ApplicationPath("resources") annotation to configure Jersey Servlet Container).

Development Steps

1. Create Maven Web Application Project
2. Project Packaging Structure
3. Update Jersey Dependencies in a Pom.Xml File
4. Create Resource - HelloWorldResource.java
5. Descriptor-Less Deployment Configuration
6. Build and Deployment
7. Conclusion

1. Create a Maven Web Application Project

Use How to Create a Web Project Using Maven in Eclipse - In this article, we will show you how to create a web project or application using maven in Eclipse IDE.

2. Project Packaging Structure

In a typical Jersey application, the project packaging structure may look:

3. Update Jersey Dependencies in a Pom.Xml File

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.javadevelopersguide.jersey</groupId>
    <artifactId>jersey-helloworld-example</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>jersey-helloworld-example Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.core</groupId>
            <artifactId>jersey-server</artifactId>
            <version>2.7</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.containers</groupId>
            <artifactId>jersey-container-servlet</artifactId>
            <version>2.7</version>
        </dependency>
    </dependencies>
    <build>
        <finalName>jersey-helloworld-example</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.0.2</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.2</version>
            </plugin>
        </plugins>
    </build>
</project>

4. Create Resource - HelloWorldResource.java

package com.javadevelopersguide.jersey.helloworld;

import javax.ws.rs.GET;

import javax.ws.rs.Path;

@Path("/")
public class HelloWorldResource {

    @GET
    @Path("helloworld")
    public String helloworld() {
        return "Helloworld !!!!";
    }
}

5. Descriptor-Less Deployment Configuration

Here are multiple deployment options in the Servlet 3.0 container for a JAX-RS application defined by implementing a custom Application subclass. For simple deployments, no web.xml is necessary at all.

Instead, an @ApplicationPath annotation can be used to annotate the custom Application subclass and define the base application URI for all JAX-RS resources configured in the application:

package com.javadevelopersguide.jersey.config;

import javax.ws.rs.ApplicationPath;

import org.glassfish.jersey.server.ResourceConfig;

@ApplicationPath("resources")
public class MyApplication extends ResourceConfig {
    public JerseyServletContainerConfig() {
        // if there are more than two packanges then separate them with semicolon
        // exmaple : packages("org.foo.rest;org.bar.rest");
        packages("com.javadevelopersguide.jersey.helloworld");
    }
}

6. Build and Deployment

Let's build this maven project using the following maven command:

mvn clean install

Or, you can build from Eclipse IDE - Right click on a project -> Run As -> Maven Build and enter below command in the wizard:

clean install

Once, build successful, then deploy this project in apache tomcat server 8.5. Once the application is up and running, type http://localhost:8080/jersey-helloworld-example/ link in a browser will show below output:

7. Conclusion

This guide illustrated how to implement a simple hello world example using the latest jersey rest 2.27 and ResourceConfig @ApplicationPath annotation based configuration.

All the code of this article is available over on Github. This is a Maven-based project, so it should be easy to import and run as it is.

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