JAX-RS JSON Rest Service with Jersey Example

In this tutorial we will show you how you can create a JSON rest service with jersey that will respond with JSON output. This tutorial covers both jersey version 1 and 2.

Maven Dependencies

<?xml version="1.0" encoding="UTF-8"?>
<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>com.memorynotfound.webservice.rs.jersey1</groupId>
    <artifactId>jersey-json</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <properties>
        <jersey.version>1.18.3</jersey.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-servlet</artifactId>
            <version>${jersey.version}</version>
        </dependency>
        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-json</artifactId>
            <version>${jersey.version}</version>
        </dependency>
    </dependencies>

</project>

<dependency>
    <groupId>org.glassfish.jersey.containers</groupId>
    <artifactId>jersey-container-servlet</artifactId>
    <version>2.14</version>
</dependency>
<dependency>
    <groupId>org.glassfish.jersey.media</groupId>
    <artifactId>jersey-media-json-jackson</artifactId>
    <version>2.14</version>
</dependency>

Model

This model will be serialized to JSON representation. Note that no annotations or default constructor is needed.

package com.memorynotfound.rs;

public class Notification {

    private Integer id;
    private String message;

    public Notification(Integer id, String message) {
        this.id = id;
        this.message = message;
    }

    public Integer getId() {
        return id;
    }

    public String getMessage() {
        return message;
    }
}

Rest Service

We create our Jersey JSON Rest service using Jackson. We will give a short explanation of what the annotations are for.

• @Path: maps the java class as a rest service to the specified path. The @Path annotation can be used on your class and/or methods. When you use this on your class this works like a base and all the methods derive from it. In our example we map our class to notification. On our method fetchBy we use a path parameter.
• @GET: maps the method to a HTTP GET request you can also use @POST, @PUT, @DELETE.
• @Produces: tells jersey which content type to serve. In our case we serve application/json
• @Consumes: tells jersey which content type to accept. In our case we consume application/json

package com.memorynotfound.rs;

import javax.ws.rs.*;
import javax.ws.rs.core.MediaType;
import java.util.ArrayList;
import java.util.List;

@Path("/notifications")
public class NotificationRestService {

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public List<Notification> fetchAll() {
        // fetch all notifications
        List<Notification> notifications = new ArrayList<Notification>();
        notifications.add(new Notification(1, "New user created"));
        notifications.add(new Notification(2, "New order created"));
        return notifications;
    }

    @GET
    @Path("{id: \\d+}")
    @Produces(MediaType.APPLICATION_JSON)
    public Notification fetchBy(@PathParam("id") int id) {
        // fetch notification by id
        return new Notification(id, "Rise and shine.");
    }

    @POST
    @Produces(MediaType.APPLICATION_JSON)
    @Consumes(MediaType.APPLICATION_JSON)
    public Notification create(Notification notification) {
        // create notification
        return notification;
    }

    @PUT
    @Consumes(MediaType.APPLICATION_JSON)
    public void update(Notification notification) {
        // update notification
    }

    @DELETE
    @Path("{id}")
    public void delete(@PathParam("id") int id) {
        // deleting notification
    }

}

Web.xml

Now we need to map our rest service to the jersey servlet. In our example we map the servlet to /api/*.

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                             http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1">

    <servlet>
        <servlet-name>Jersey-Servlet</servlet-name>
        <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Jersey-Servlet</servlet-name>
        <url-pattern>/api/*</url-pattern>
    </servlet-mapping>

</web-app>

<servlet>
    <servlet-name>Jersey-Servlet</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.memorynotfound.rs</param-value>
    </init-param>
</servlet>

Demo

URL: http://localhost:8080/jersey-json/api/notifications

References

• JAX-RS Documentation
• JAX-RS @GET, @POST, @PUT, @DELETE

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