Embedded Jetty & Jersey Example

In this post, I am going to explain how to integrate Jersey with Embedded jetty server.

If you want to know about REST in detail, you can go through the following tutorial.

https://self-learning-java-tutorial.blogspot.com/2015/08/jersey-rest-tutorial.html

If you want to know about Jetty server, you can go through following tutorial.

https://self-learning-java-tutorial.blogspot.com/2015/10/jetty-tutorial.html

Following step-by-step procedure explains the implementation and deployment of complete application.

Step 1: Create new Maven project ‘jetty_tutorial’ in Eclipse.

File -> New -> Other. Select 'Maven Project'. Give the project name as 'jetty_tutorial'.

Step 2: Open pom.xml and update the maven dependencies. I am using following maven dependencies.

<dependencies>
  <dependency>
   <groupId>org.eclipse.jetty</groupId>
   <artifactId>jetty-server</artifactId>
   <version>9.4.0.RC1</version>
  </dependency>
  <dependency>
   <groupId>org.eclipse.jetty</groupId>
   <artifactId>jetty-servlet</artifactId>
   <version>9.4.0.RC1</version>
  </dependency>
  <dependency>
   <groupId>org.glassfish.jersey.core</groupId>
   <artifactId>jersey-server</artifactId>
   <version>2.15</version>
  </dependency>
  <dependency>
   <groupId>org.glassfish.jersey.containers</groupId>
   <artifactId>jersey-container-servlet-core</artifactId>
   <version>2.15</version>
  </dependency>
  <dependency>
   <groupId>org.glassfish.jersey.containers</groupId>
   <artifactId>jersey-container-jetty-http</artifactId>
   <version>2.15</version>
  </dependency>
  <dependency>
   <groupId>org.glassfish.jersey.media</groupId>
   <artifactId>jersey-media-moxy</artifactId>
   <version>2.15</version>
  </dependency>
 </dependencies>

Step 3: Create new package 'com.sample'. Add the class HelloWorld.java.

HelloWorld.java

package com.sample;

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

@Path("/hello")
public class HelloWorld {
 @GET
 @Path("test")
 @Produces(MediaType.TEXT_PLAIN)
 public String test() {
  return "Test";
 }
}

Step 4: Define App.java like below.

App.java

package com.sample;

import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;

public class App {
 public static void main(String[] args) throws Exception {
  ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
  context.setContextPath("/");

  Server jettyServer = new Server(8080);
  jettyServer.setHandler(context);

  ServletHolder jerseyServlet = context.addServlet(org.glassfish.jersey.servlet.ServletContainer.class, "/*");
  jerseyServlet.setInitOrder(0);

  jerseyServlet.setInitParameter("jersey.config.server.provider.classnames", HelloWorld.class.getCanonicalName());

  try {
   jettyServer.start();
   jettyServer.join();
  } catch (Exception e) {
   e.printStackTrace();
  } finally{
   jettyServer.destroy();
  }
 }
}

Run ‘App.java’, you can able to see following log messages in console.

2016-11-15 13:42:19.682:INFO::main: Logging initialized @245ms to org.eclipse.jetty.util.log.StdErrLog
2016-11-15 13:42:19.828:INFO:oejs.Server:main: jetty-9.4.0.RC1
2016-11-15 13:42:19.828:WARN:oejs.Server:main: THIS IS NOT A STABLE RELEASE! DO NOT USE IN PRODUCTION!
2016-11-15 13:42:19.828:WARN:oejs.Server:main: Download a stable release from http://download.eclipse.org/jetty/
2016-11-15 13:42:19.876:INFO:oejs.session:main: DefaultSessionIdManager workerName=node0
2016-11-15 13:42:19.876:WARN:oejs.session:main: No SessionScavenger set, using defaults
2016-11-15 13:42:19.879:INFO:oejs.session:main: Scavenging every 600000ms
2016-11-15 13:42:20.712:INFO:oejsh.ContextHandler:main: Started o.e.j.s.ServletContextHandler@1f9e9475{/,null,AVAILABLE}
2016-11-15 13:42:21.022:INFO:oejs.AbstractConnector:main: Started ServerConnector@2506fbde{HTTP/1.1,[http/1.1]}{0.0.0.0:8080}
2016-11-15 13:42:21.023:INFO:oejs.Server:main: Started @1588ms

Open any browser and hit the url ‘http://localhost:8080/hello/test’, you can able to see the message ‘Test’ in browser body.

Returning a json response using embedded jetty. 

Following step-by-step procedure explains how to send json response.

Address.java

package com.sample;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Address {
 private String street;
 private String city;
 private String state;
 private String country;

 public Address() {
  this("No Data", "No Data", "No Data", "No Data");
 }

 public Address(String area, String city, String state, String country) {
  super();
  this.street = area;
  this.city = city;
  this.state = state;
  this.country = country;
 }

 public String getArea() {
  return street;
 }

 public String getCity() {
  return city;
 }

 public String getCountry() {
  return country;
 }

 public String getState() {
  return state;
 }

 public void setArea(String area) {
  this.street = area;
 }

 public void setCity(String city) {
  this.city = city;
 }

 public void setCountry(String country) {
  this.country = country;
 }

 public void setState(String state) {
  this.state = state;
 }

}

Employee.java

package com.sample;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Employee {
 private String firstName;
 private String lastName;
 private long id;
 private Address permAddrees;
 private Address tempAddrees;

 public Employee() {
  this("No Data", "No Data", -1, new Address(), new Address());
 }

 public Employee(String firstName, String lastName, long id, Address permAddrees, Address tempAddrees) {
  super();
  this.firstName = firstName;
  this.lastName = lastName;
  this.id = id;
  this.permAddrees = permAddrees;
  this.tempAddrees = tempAddrees;
 }

 public String getFirstName() {
  return firstName;
 }

 public void setFirstName(String firstName) {
  this.firstName = firstName;
 }

 public String getLastName() {
  return lastName;
 }

 public void setLastName(String lastName) {
  this.lastName = lastName;
 }

 public long getId() {
  return id;
 }

 public void setId(long id) {
  this.id = id;
 }

 public Address getPermAddrees() {
  return permAddrees;
 }

 public void setPermAddrees(Address permAddrees) {
  this.permAddrees = permAddrees;
 }

 public Address getTempAddrees() {
  return tempAddrees;
 }

 public void setTempAddrees(Address tempAddrees) {
  this.tempAddrees = tempAddrees;
 }

}

EmployeeService.java

package com.sample;

import java.util.HashMap;
import java.util.Map;

public class EmployeeService {
 private static Map<Long, Employee> employees = new HashMap<>();

 static {
  initializeEmployees();
 }

 private static void initializeEmployees() {
  Address tempAddr1 = new Address("Electronic City", "Bangalore", "Karnataka", "India");
  Address tempAddr2 = new Address("BTM Layout", "Bangalore", "Karnataka", "India");
  Address permAddr1 = new Address("Marthali", "Bangalore", "Karnataka", "India");
  Address permAddr2 = new Address("Bharath Nagar", "Hyderabad", "Andhra Pradesh", "India");

  Employee emp1 = new Employee("Hari Krishna", "Gurram", 1, permAddr1, tempAddr1);
  Employee emp2 = new Employee("PTR", "PTR", 2, permAddr2, tempAddr2);

  employees.put(1l, emp1);
  employees.put(2l, emp2);
 }

 public static Map<Long, Employee> getAllEmployees() {
  return employees;
 }

 public static Employee getEmployee(long id) {
  return employees.get(id);
 }
}

EmployeeResource.java

package com.sample;

import java.util.ArrayList;
import java.util.List;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

@Path("employees")
public class EmployeeResource {

 @GET
 @Produces(MediaType.APPLICATION_JSON)
 public List<Employee> getAllEmployees() {
  return new ArrayList<>(EmployeeService.getAllEmployees().values());
 }

 @GET
 @Path("/{employeeId}")
 @Produces(MediaType.APPLICATION_JSON)
 public Employee getEmployee(@PathParam("employeeId") long empId) {
  return EmployeeService.getEmployee(empId);
 }

}

App.java

package com.sample;

import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;

public class App {
 public static void main(String[] args) throws Exception {
  ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
  context.setContextPath("/");

  Server jettyServer = new Server(8080);
  jettyServer.setHandler(context);

  ServletHolder jerseyServlet = context.addServlet(org.glassfish.jersey.servlet.ServletContainer.class, "/*");
  jerseyServlet.setInitOrder(0);

  jerseyServlet.setInitParameter("jersey.config.server.provider.classnames",
    EmployeeResource.class.getCanonicalName());

  try {
   jettyServer.start();
   jettyServer.join();
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   jettyServer.destroy();
  }
 }
}

Open any browser, hit the url 'http://localhost:8080/employees/2'. You can able to see following json response.

{"firstName":"PTR","id":2,"lastName":"PTR","permAddrees":{"area":"Bharath Nagar","city":"Hyderabad","country":"India","state":"Andhra Pradesh"},"tempAddrees":{"area":"BTM Layout","city":"Bangalore","country":"India","state":"Karnataka"}}

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