RESTful Web Services in Java

Dhanoop Bhaskar August 22, 2016 java
Read about REST here...
In the example program REST is implemented using Jersey Framework.
Download Jersey framework from here...
I used Dynamic Web Project in Eclipse for coding. Extract jersey zip file and copy all the .jar files from api, ext, lib folders to WebContent/WEB-INF/lib folder.

Employee.java 
 
package in.theinsanetechie.rest;

import java.io.Serializable;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "employee")
public class Employee implements Serializable {

 private static final long serialVersionUID = 1L;
 private int empcode;
 private String name;
 private String designation;
 private float basicpay;
 
 public Employee() {  
 }
 
 public Employee(int empcode, String name, String designation, float basicpay) {
  super();
  this.empcode = empcode;
  this.name = name;
  this.designation = designation;
  this.basicpay = basicpay;
 }

 public int getEmpcode() {
  return empcode;
 }
 
 @XmlElement
 public void setEmpcode(int empcode) {
  this.empcode = empcode;
 }
 
 public String getName() {
  return name;
 }
 
 @XmlElement
 public void setName(String name) {
  this.name = name;
 }
 
 public String getDesignation() {
  return designation;
 }
 
 @XmlElement
 public void setDesignation(String designation) {
  this.designation = designation;
 }
 
 public float getBasicpay() {
  return basicpay;
 }
 
 @XmlElement
 public void setBasicpay(float basicpay) {
  this.basicpay = basicpay;
 }

 @Override
 public boolean equals(Object obj) {
  if (this == obj)
   return true;
  if (obj == null)
   return false;
  if (getClass() != obj.getClass())
   return false;
  Employee other = (Employee) obj;
  if (Float.floatToIntBits(basicpay) != Float
    .floatToIntBits(other.basicpay))
   return false;
  if (designation == null) {
   if (other.designation != null)
    return false;
  } else if (!designation.equals(other.designation))
   return false;
  if (empcode != other.empcode)
   return false;
  if (name == null) {
   if (other.name != null)
    return false;
  } else if (!name.equals(other.name))
   return false;
  return true;
 }

}


EmployeeAccessObject.java 
 
package in.theinsanetechie.rest;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.List;

public class EmployeeAccessObject {

 private String fileName = "Employee.dat";
 
 @SuppressWarnings("unchecked")
 public List getFullList() {
  List list = null;
  File file = new File(fileName);
  try {
   if (file.exists()) {
    FileInputStream fileInputStream = new FileInputStream(file);
    ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
    list = (List) objectInputStream.readObject();
    objectInputStream.close();
   } else{
    Employee employee = new Employee(1001, "The Insane Techie", "Dev", 99999.99f);
    list = new ArrayList();
    list.add(employee);
    saveList(list);
   }
   
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  } catch (ClassNotFoundException e) {
   e.printStackTrace();
  }
  
  return list;
 }
 
 public Employee get(int empcode) {
  List list = getFullList();
  
  for (Employee temp : list) {
   if (temp.getEmpcode() == empcode) {
    return temp;
   }
  }
  
  return null;
 }
 
 public boolean addToList(Employee emp){
  List list = getFullList();
  boolean exists = false;
  for(Employee temp: list){
   if(temp.getEmpcode() == emp.getEmpcode()){
    exists = true;
    break;
   }
  }  
  if(!exists){
   list.add(emp);
   saveList(list);
   return true;
  }
  return false;
 }
 
 public boolean updateList(Employee emp){
  List list = getFullList();
  for(Employee temp: list){
   if(temp.getEmpcode() == emp.getEmpcode()){
    int index = list.indexOf(temp);   
    list.set(index, emp);
    saveList(list);
    return true;
   }
  }  
  return false;
 }

 public boolean deleteFromList(int empcode){
  List list = getFullList();

  for(Employee temp: list){
   if(temp.getEmpcode() == empcode){
    int index = list.indexOf(temp);   
    list.remove(index);
    saveList(list);
    return true;   
   }
  }  
  return false;
 }
 
 private void saveList(List list) {
  
  File file = new File(fileName);
  try {
   FileOutputStream fileOutputStream = new FileOutputStream(file);
   ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
   objectOutputStream.writeObject(list);
   objectOutputStream.close();
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
  
 }
}


EmployeeService.java 
 
package in.theinsanetechie.rest;

import java.io.IOException;
import java.util.List;

import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.FormParam;
import javax.ws.rs.GET;
import javax.ws.rs.OPTIONS;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;

@Path("/EmployeeService")
public class EmployeeService {

 EmployeeAccessObject accessObject = new EmployeeAccessObject();
 private static final String SUCCESS = "success";
 private static final String FAILURE = "failure";


 @GET
 @Path("/employees")
 @Produces(MediaType.APPLICATION_XML)
 public List getFullList(){
  return accessObject.getFullList();
 }

 @GET
 @Path("/employees/{empcode}")
 @Produces(MediaType.APPLICATION_XML)
 public Employee get(@PathParam("empcode") int empcode){
  return accessObject.get(empcode);
 }

 @PUT
 @Path("/employees")
 @Produces(MediaType.APPLICATION_XML)
 @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
 public String add(@FormParam("empcode") int empcode,
   @FormParam("name") String name,
   @FormParam("designation") String designation,
   @FormParam("basicpay") float basicpay,
   @Context HttpServletResponse servletResponse) throws IOException{
  Employee emp = new Employee(empcode, name, designation, basicpay);
  boolean result = accessObject.addToList(emp);
  if(result == true){
   return SUCCESS;
  }
  return FAILURE;
 }

 @POST
 @Path("/employees")
 @Produces(MediaType.APPLICATION_XML)
 @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
 public String update(@FormParam("empcode") int empcode,
   @FormParam("name") String name,
   @FormParam("designation") String designation,
   @FormParam("basicpay") float basicpay,
   @Context HttpServletResponse servletResponse) throws IOException{
  Employee emp = new Employee(empcode, name, designation, basicpay);
  boolean result = accessObject.updateList(emp);
  if(result == true){
   return SUCCESS;
  }
  return FAILURE;
 }

 @DELETE
 @Path("/employees/{empcode}")
 @Produces(MediaType.APPLICATION_XML)
 public String deleteUser(@PathParam("empcode") int empcode){
  boolean result = accessObject.deleteFromList(empcode);
  if(result == true){
   return SUCCESS;
  }
  return FAILURE;
 }

 @OPTIONS
 @Path("/employees")
 @Produces(MediaType.APPLICATION_XML)
 public String getSupportedOperations(){
  return "GET, PUT, POST, DELETE";
 }
}


WebServiceTester.java 
 
package in.theinsanetechie.rest;

import java.util.List;

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Entity;
import javax.ws.rs.core.Form;
import javax.ws.rs.core.GenericType;
import javax.ws.rs.core.MediaType;

public class WebServiceTester  {

 private Client client;
 private String REST_SERVICE_URL = "http://localhost:8080/EmployeeManagement/rest/EmployeeService/employees";
 private static final String SUCCESS="success";
 private static final String PASS = "pass";
 private static final String FAIL = "fail";

 private void init(){
  this.client = ClientBuilder.newClient();
 }

 public static void main(String[] args){
  
  WebServiceTester tester = new WebServiceTester();  
  tester.init();
  tester.testGetFullList();
  tester.testGet();
  tester.testUpdate();
  tester.testAdd();
  tester.testDelete();
 }
 
 private void testGetFullList(){
  GenericType> list = new GenericType>() {};
  List employees = client
    .target(REST_SERVICE_URL)
    .request(MediaType.APPLICATION_XML)
    .get(list);
  String result = PASS;
  if(employees.isEmpty()){
   result = FAIL;
  }
  System.out.println("Test case name: testGetFullList, Result: " + result );
 }

 private void testGet(){
  Employee sampleEmp = new Employee();
  sampleEmp.setEmpcode(1001);

  Employee emp = client
    .target(REST_SERVICE_URL)
    .path("/{empcode}")
    .resolveTemplate("empcode", 1001)
    .request(MediaType.APPLICATION_XML)
    .get(Employee.class);
  String result = FAIL;
  if(sampleEmp != null && sampleEmp.getEmpcode() == emp.getEmpcode()){
   result = PASS;
  }
  System.out.println("Test case name: testGet, Result: " + result );
 }

 private void testUpdate(){
  Form form = new Form();
  form.param("empcode", "1001");
  form.param("name", "Dhanoop Bhaskar");
  form.param("designation", "Computer Scientist");
  form.param("basicpay", "100000.00f");

  String callResult = client
    .target(REST_SERVICE_URL)
    .request(MediaType.APPLICATION_XML)
    .post(Entity.entity(form,
      MediaType.APPLICATION_FORM_URLENCODED_TYPE),
      String.class);
  String result = PASS;
  if(!SUCCESS.equals(callResult)){
   result = FAIL;
  }

  System.out.println("Test case name: testUpdate, Result: " + result );
 }
 
 private void testAdd(){
  Form form = new Form();
  form.param("empcode", "1002");
  form.param("name", "The Insane Techie");
  form.param("designation", "Computer Scientist");
  form.param("basicpay", "100000.00f");

  String callResult = client
    .target(REST_SERVICE_URL)
    .request(MediaType.APPLICATION_XML)
    .put(Entity.entity(form,
      MediaType.APPLICATION_FORM_URLENCODED_TYPE),
      String.class);

  String result = PASS;
  if(!SUCCESS.equals(callResult)){
   result = FAIL;
  }

  System.out.println("Test case name: testAdd, Result: " + result );
 }
 
 private void testDelete(){
  String callResult = client
    .target(REST_SERVICE_URL)
    .path("/{empcode}")
    .resolveTemplate("empcode", 1002)
    .request(MediaType.APPLICATION_XML)
    .delete(String.class);

  String result = PASS;
  if(!SUCCESS.equals(callResult)){
   result = FAIL;
  }

  System.out.println("Test case name: testDelete, Result: " + result );
 }
}


web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    id="WebApp_ID" version="3.0">
    <display-name>Employee Management</display-name>
    <servlet>
        <servlet-name>Jersey RESTful Application</servlet-name>
        <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
            <init-param>
                <param-name>jersey.config.server.provider.packages</param-name>
                <param-value>in.theinsanetechie.rest</param-value>
            </init-param>
        </servlet>
    <servlet-mapping>
    <servlet-name>Jersey RESTful Application</servlet-name>
        <url-pattern>/rest/*</url-pattern>
    </servlet-mapping>
</web-app>

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1 Comments

  1. maqMarch 1, 2017 at 12:08 PM

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