Convert List Objects to/from JSON in Java Restful Web Services and Hibernate

Java Libraries

Use JAR files which are listed below:

antlr-2.7.7.jar
asm-3.1.jar
commons-logging-1.1.3.jar
dom4j-1.6.1.jar
genson-1.3.jar
hibernate-commons-annotations-4.0.2.Final.jar
hibernate-core-4.2.5.Final.jar
hibernate-jpa-2.0-api-1.0.1.Final.jar
jackson-core-asl-1.9.2.jar
jackson-jaxrs-1.9.2.jar
jackson-mapper-asl-1.9.2.jar
jackson-xc-1.9.2.jar
javassist-3.15.0-GA.jar
javax.servlet.jsp.jstl-1.2.2.jar
javax.servlet.jsp.jstl-api-1.2.1.jar
jboss-logging-3.1.0.GA.jar
jboss-transaction-api_1.1_spec-1.0.1.Final.jar
jersey-client-1.18.jar
jersey-core-1.18.jar
jersey-json-1.19.3.jar
jersey-server-1.18.jar
jersey-servlet-1.18.jar
jettison-1.1.jar
jsr311-api-1.1.1.jar
mysql-connector-java-5.1.36.jar
taglibs-standard-impl-1.2.1.jar

Create Database

Create a database with the name is learnjavarestfulwebservices. This database have a table: product table.

--
-- Table structure for table `product`
--

CREATE TABLE `product` (
  `id` int(11) NOT NULL PRIMARY KEY AUTO_INCREMENT,
  `name` varchar(250) NOT NULL,
  `price` decimal(10,1) NOT NULL,
  `quantity` int(11) NOT NULL,
  `status` tinyint(1) NOT NULL,
  `creationDate` date NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

--
-- Dumping data for table `product`
--

INSERT INTO `product` (`name`, `price`, `quantity`, `status`, `creationDate`) VALUES('name 1', '12.2', 2, 1, '2017-12-28');
INSERT INTO `product` (`name`, `price`, `quantity`, `status`, `creationDate`) VALUES('name 2', '6.5', 6, 0, '2017-12-29');
INSERT INTO `product` (`name`, `price`, `quantity`, `status`, `creationDate`) VALUES('name 3', '11.8', 8, 1, '2017-12-18');

Structure of Product Table

Data of Product Table

Entities Class

Create 2 entities classes – Product.java and ProductEntity.java, to represent the above tables

Product.java

package entities;

import java.io.Serializable;
import java.math.BigDecimal;
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.xml.bind.annotation.XmlRootElement;

@Entity
@Table(name = "product")
@XmlRootElement(name = "product")
public class Product implements Serializable {


	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column
	private int id;
	private String name;
	private BigDecimal price;
	private int quantity;
	private boolean status;
	private Date creationDate;

	public int getId() {
		return id;
	}

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

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public BigDecimal getPrice() {
		return price;
	}

	public void setPrice(BigDecimal price) {
		this.price = price;
	}

	public int getQuantity() {
		return quantity;
	}

	public void setQuantity(int quantity) {
		this.quantity = quantity;
	}

	public boolean isStatus() {
		return status;
	}

	public void setStatus(boolean status) {
		this.status = status;
	}

	public Date getCreationDate() {
		return creationDate;
	}

	public void setCreationDate(Date creationDate) {
		this.creationDate = creationDate;
	}

}

ProductEntity.java

package entities;

import java.io.Serializable;
import java.math.BigDecimal;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "productEntity")
public class ProductEntity implements Serializable {

	private int id;
	private String name;
	private BigDecimal price;
	private int quantity;
	private boolean status;
	private String creationDate;

	public int getId() {
		return id;
	}

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

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public BigDecimal getPrice() {
		return price;
	}

	public void setPrice(BigDecimal price) {
		this.price = price;
	}

	public int getQuantity() {
		return quantity;
	}

	public void setQuantity(int quantity) {
		this.quantity = quantity;
	}

	public boolean isStatus() {
		return status;
	}

	public void setStatus(boolean status) {
		this.status = status;
	}

	public String getCreationDate() {
		return creationDate;
	}

	public void setCreationDate(String creationDate) {
		this.creationDate = creationDate;
	}

}

Hibernate Configuration File

Puts Product.java in your Hibernate configuration file, and also MySQL connection details.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
                                         "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
	<session-factory>
		<property name="hibernate.enable_lazy_load_no_trans">true</property>
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/learnjavarestfulwebservices</property>
		<property name="hibernate.connection.username">root</property>
		<property name="hibernate.connection.password">123456</property>
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		<property name="hibernate.current_session_context_class">thread</property>
		<mapping class="entities.Product" />
	</session-factory>
</hibernate-configuration>

Create HibernateUtil class

The HibernateUtil class helps in creating the SessionFactory from the Hibernate configuration file. The SessionFactory is threadsafe, so it is not necessary to obtain one for each thread.

package models;

import org.hibernate.*;
import org.hibernate.boot.*;
import org.hibernate.boot.registry.*;

public class HibernateUtil {

	private static final SessionFactory sessionFactory;

	static {
		try {
			StandardServiceRegistry standardRegistry = new
					StandardServiceRegistryBuilder()
					.configure("hibernate.cfg.xml")
					.build();
			Metadata metaData = new MetadataSources(
					standardRegistry)
					.getMetadataBuilder()
					.build();
			sessionFactory = metaData.getSessionFactoryBuilder().build();
		} catch (Throwable th) {
			throw new ExceptionInInitializerError(th);
		}
	}

	public static SessionFactory getSessionFactory() {
		return sessionFactory;

	}
}

Create ProductModel class

The ProductModel class contains methods to interact with the database.

package models;

import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.transform.Transformers;
import entities.ProductEntity;

public class ProductModel {

	private SessionFactory sessionFactory = HibernateUtil.getSessionFactory();

	public List<ProductEntity> findAll() {
		List<ProductEntity> productEntities = null;
		Session session = null;
		Transaction transaction = null;
		try {
			session = sessionFactory.openSession();
			transaction = session.beginTransaction();
			Query query = session.createQuery("select p.id as id, "
												+ "p.name as name, "
												+ "p.price as price, "
												+ "p.quantity as quantity, "
												+ "p.status as status, "
												+ "DATE_FORMAT(p.creationDate, '%Y-%m-%d') as creationDate "
												+ "from Product p");
			productEntities = query.setResultTransformer(
								Transformers.aliasToBean(ProductEntity.class)
							  ).list();
			transaction.commit();
		} catch (Exception e) {
			productEntities = null;
			if (transaction != null) {
				transaction.rollback();
			}
		} finally {
			session.close();
		}
		return productEntities;
	}

}

Create Server Project

Create Dynamic Web Project in Eclipse. Copy all jar files above to the lib directory in the project

Create ApplicationConfig Class

This class is used to register a URL pattern in Jersey to intercept HTTP calls to the service. The marshaller, Jersey intercepts the path given in @ApplicationPath annotation such as – @ApplicationPath(“api”). This class extends javax.ws.rs.core.Application. All the RESTful web services and extensions needed are registered here.

ApplicationConfig.java

package ws;

import java.util.Set;
import javax.ws.rs.core.Application;

@javax.ws.rs.ApplicationPath("api")
public class ApplicationConfig extends Application {

	@Override
	public Set<Class<?>> getClasses() {
		Set<Class<?>> resources = new java.util.HashSet<>();
		addRestResourceClasses(resources);
		return resources;
	}

	private void addRestResourceClasses(Set<Class<?>> resources) {
		resources.add(controllers.ProductRestController.class);
	}

}

Create Restful Web Services

Create Restful Web Services provides application/json data for the client

package controllers;

import java.util.List;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.GenericEntity;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import entities.ProductEntity;
import models.ProductModel;

@Path("product")
public class ProductRestController {

	@GET
	@Path("find_all")
	@Produces({ MediaType.APPLICATION_JSON })
	public Response findAll() {
		try {
			ProductModel productModel = new ProductModel();
			GenericEntity<List<ProductEntity>> genericEntity =
				new GenericEntity<List<ProductEntity>>(productModel.findAll()){};
			return Response.ok(genericEntity).build();
		} catch (Exception e) {
			return Response.status(Response.Status.BAD_REQUEST).build();
		}
	}

}

Testing Restful Web Services

Access restful web services use the following url: http://localhost:8080/LearnJavaRestfulWebServices_Server/api/product/find_all

Output

[
	{"creationDate":"2017-12-28","id":1,"name":"name 1","price":12.2,"quantity":2,"status":true},
	{"creationDate":"2017-12-29","id":2,"name":"name 2","price":6.5,"quantity":6,"status":false},
	{"creationDate":"2017-12-18","id":3,"name":"name 3","price":11.8,"quantity":8,"status":true}
]

Consume Restful Web Services from Java Application

Create Java Project in Eclipse. Add all jar files above to the project

Entity Class

Create entities package in client project. Create a entity class: ProductEntity.java as below

ProductEntity.java

package entities;

import java.io.Serializable;
import java.math.BigDecimal;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "productEntity")
public class ProductEntity implements Serializable {

	private int id;
	private String name;
	private BigDecimal price;
	private int quantity;
	private boolean status;
	private String creationDate;

	public int getId() {
		return id;
	}

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

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public BigDecimal getPrice() {
		return price;
	}

	public void setPrice(BigDecimal price) {
		this.price = price;
	}

	public int getQuantity() {
		return quantity;
	}

	public void setQuantity(int quantity) {
		this.quantity = quantity;
	}

	public boolean isStatus() {
		return status;
	}

	public void setStatus(boolean status) {
		this.status = status;
	}

	public String getCreationDate() {
		return creationDate;
	}

	public void setCreationDate(String creationDate) {
		this.creationDate = creationDate;
	}

}

Create DemoRestClientModel

DemoRestClientModel class contain methods call restful web services

package models;

import javax.ws.rs.core.MediaType;
import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.DefaultClientConfig;

public class ProductRestClientModel {

	private String BASE_URL = "http://localhost:8080/LearnJavaRestfulWebServices_Server/api/";
	private WebResource webResource;
	private Client client;

	public ProductRestClientModel() {
		this.client = Client.create(new DefaultClientConfig());
		this.webResource = this.client.resource(BASE_URL).path("product");
	}

	public ClientResponse findAll() {
		ClientResponse response = null;
		try {
			WebResource resource = this.webResource;
			response = resource.path("find_all")
								.accept(MediaType.APPLICATION_JSON)
								.get(ClientResponse.class);
		} catch (Exception e) {
			response = null;
		}
		return response;
	}

}

Run It

package demo;

import java.util.List;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.GenericType;
import entities.ProductEntity;
import models.ProductRestClientModel;

public class Main {

	public static void main(String[] args) {

		ProductRestClientModel productRestClientModel = new ProductRestClientModel();
		ClientResponse response = productRestClientModel.findAll();
		if(response != null) {
			int statusCode = response.getStatus();
			System.out.println("Response Status: " + statusCode);
			GenericType<List<ProductEntity>> genericEntity =
				new GenericType<List<ProductEntity>>(){};
			List<ProductEntity> productEntities = response.getEntity(genericEntity);
			System.out.println("\nProduct List");
			for(ProductEntity productEntity : productEntities) {
				System.out.println("Id: " + productEntity.getId());
				System.out.println("Name: " + productEntity.getName());
				System.out.println("Price: " + productEntity.getPrice());
				System.out.println("Quantity: " + productEntity.getQuantity());
				System.out.println("Status: " + productEntity.isStatus());
				System.out.println("Creation Date: " + productEntity.getCreationDate());
				System.out.println("=========================");
			}
		} else {
			System.err.println("Can not access find_all web method");
		}

	}

}

Output

Response Status: 200

Product List
Id: 1
Name: name 1
Price: 12.2
Quantity: 2
Status: true
Creation Date: 2017-12-28
=========================
Id: 2
Name: name 2
Price: 6.5
Quantity: 6
Status: false
Creation Date: 2017-12-29
=========================
Id: 3
Name: name 3
Price: 11.8
Quantity: 8
Status: true
Creation Date: 2017-12-18
=========================