Introduction
OAuth2 is a token-based security authentication and authorization framework that breaks security down into four components. These four components are 

OAuth2 is a token-based security framework. A user authenticates against the OAuth2 server by providing their credentials along with the application that they’re using to access the resource. If the user’s credentials are valid, the OAuth2 server provides a token that can be presented every time a service being used by the user’s application tries to access a protected resource (the microservice). The OAuth2 specification has four types of grants: 

For Example: You have to Create Project Node Name is: "a143mk-Oauth2-Security" on STS4 Tools.

The first thing to note in this listing is the @EnableAuthorizationServer annotation. This annotation tells Spring Cloud that this service will be used as an OAuth2 service and to add several REST-based endpoints that will be used in the OAuth2 authentication and authorization processes.

For step by step development working watch the video and learn yourself.

Introduction:
In this article will look into how to create a REST API using HTTP methods for Create and Retrieve operations in Spring Boot along with MYSQL database. Spring Boot is an open source Java-based framework to build enterprise spring applications. . 

Overview: 

Create MYSQL database using WampServer.
Download WampServer install and Run-> go to phpMyAdmin and click.  

Open localhost/phpmyadmin/ 

Create Database Name is “hostel”.

Crate Table in hostel Database. Table Name is states with number of fields/Column.

Create Table column name, which is show in image.

Create the Spring Boot Project from STS-4:
It will write project name, group, artifact, version, description, package etc. 

 

Create Entity model class. 

• Create the States model class to map with the States table.
• @Entity is used to annotate that the class is an entity in the database.
• @Table is used to annotate name of table in the database.
• @id is used to reference that widget to your java file and access it from java file.
• @GeneratedValue is used to generation strategies for the values of primary keys.

Create JPA Data Repository. 

• Create StatsRepository Repository interface extending JPA Repository.
• There are not need writing any SQL/MySql etc query.
• @Repository annotation is used to indicate that the class provides the mechanism for storage, retrieval, search, and update and delete operation on objects.

• Create StateService service class to code the business logic and it acts as a middle layer between repository and controller class.
• @Service annotation is a specialization of @Component annotation. Spring Service annotation can be applied only to classes. It is used to mark the class as a service provider.
• @Transactional StateService annotate methods are executed in transactions.
  Example:
  @Transactional(readOnly = false, rollbackFor={Throwable.class, Exception.class}, propagation = Propagation.SUPPORTS)
• @Autowired annotation is used for automatic dependency injection. Spring framework is built on dependency injection and we inject the class dependencies through spring bean configuration file.

Create Rest Controllers class. 

• Create Rest StateController Controller class which contains all REST API endpoints for Create and Retrieve operations.
• @RestController annotation was introduced in Spring 4.0 to simplify the creation of REST web services. It's a convenience annotation that combines @Controller and @ResponseBody– which eliminates the need to annotate every request handling method of the controller class with the @ResponseBody annotation.

Run the Project:
Write click to project and Run as->Spring boot App, it will check console to run project success and check running port.  

Testing using Postman.
Execute GET Request method to add a States to the Database. 

 

Video Link for watching How to build API.

It is defined as follows

• Models: Models are object used as blueprints for all of the objects that will be used in the application. 
• Views: views are used to represent the presentational aspect of the information and data located in the models. 
• Controller: controller are act as both of the models as well as views. They serve as a connection between the models and views.

public class Collage { private String rollNo; private String name; public String getRollNo() { return rollNo; } public void setRollNo(String rollNo) { this.rollNo = rollNo; } public String getName() { return name; } public void setName(String name) { this.name = name; } }
Step 2. Create View.
CollageView.java
public class CollageView { public void printCollageDetails(String CollageName, String CollageRollNo){ System.out.println("Collage: "); System.out.println("Name: " + CollageName); System.out.println("Roll No: " + CollageRollNo); } }
Step 3. Create Controller.
CollageController.java
public class CollageController { private Collage model; private CollageView view; public CollageController(Collage model, CollageView view){ this.model = model; this.view = view; } public void setCollageName(String name){ model.setName(name); } public String getCollageName(){ return model.getName(); } public void setCollageRollNo(String rollNo){ model.setRollNo(rollNo); } public String getCollageRollNo(){ return model.getRollNo(); } public void updateView(){ view.printCollageDetails(model.getName(), model.getRollNo()); } }
Step 4. Use the CollageController methods to demonstrate MVC design pattern usage.
MVCPatternDemo.java
public static void main(String[] args) { //fetch Collage record based on his roll no from the database Collage model = retriveCollageFromDatabase(); //Create a view : to write Collage details on console CollageView view = new CollageView(); CollageController controller = new CollageController(model, view); controller.updateView(); //update model data controller.setCollageName("Manoj"); controller.updateView(); } private static Collage retriveCollageFromDatabase(){ Collage Collage = new Collage(); Collage.setName("ABCD"); Collage.setRollNo("20"); return Collage; } }

Spring is a lightweight framework. it provides support to various frameworks such as Hibernate, Struts, Tapestry, EJB, JSF, etc.
Modules: IOC(Inversion of control),  AOP(Aspect Oriented Programming), DAO(Data Access Object), Context,ORM(Object-relational Mapping), Web, MVC(Model View Controller). etc.

This is a step-by-step tutorial that helps you build a Spring-Hibernate application easily in a clear and concise way. In this first part, we demonstrate how to code a simple Spring MVC application that displays a list of users from MySQL database.
1. Create Database Name is demo and Database Table name is springhibernet.
/* EMPLOYEE table */ CREATE TABLE `springhibernet` ( `employee_id` BIGINT( 10 ) NOT NULL AUTO_INCREMENT , `firstname` VARCHAR( 50 ) NULL DEFAULT NULL , `lastname` VARCHAR( 50 ) NULL DEFAULT NULL , `birth_date` DATE NOT NULL , `cell_phone` VARCHAR( 15 ) NOT NULL , PRIMARY KEY ( `employee_id` ) )
Open NetBeans See The Menu Bar go to the file Menu Click on the New Project(Ctrl+Shift+N) and Select Left site categories Java/java web and Project categories to Right Site Project java/web Application .You have to give The Program Name "SpringHibernateTutorial". if you wont to save Project Location you can Browse and File save on the direction place and Gone a default Place and Now uncheck/check the check box and click on the next button, select server settings and select The Spring Web MVC Framework 4.0 and Hibernate Framework 4.3 and go to the finish.

This is automatic generated page code with custom according to performance.  
2.applicationContext.xml
<?xml version='1.0' encoding='UTF-8' ?> <!-- was: <?xml version="1.0" encoding="UTF-8"?> --> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd"> <!--bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer" p:location="/WEB-INF/jdbc.properties" /> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource" p:driverClassName="${jdbc.driverClassName}" p:url="${jdbc.url}" p:username="${jdbc.username}" p:password="${jdbc.password}" /--> <!-- ADD PERSISTENCE SUPPORT HERE (jpa, hibernate, etc) --> </beans>
3.dispatcher-servlet.xml
<?xml version='1.0' encoding='UTF-8' ?> <!-- was: <?xml version="1.0" encoding="UTF-8"?> --> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd"> <bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping"/> <!-- Add view.class bean --> <bean class="com.spring.module.view" id="viewckey" /> <!-- Most controllers will use the ControllerClassNameHandlerMapping above, but for the index controller we are using ParameterizableViewController, so we must define an explicit mapping for it. --> <bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping"> <property name="mappings"> <props> <prop key="index.htm">indexController</prop> <!--Add view.htm --> <prop key="view.htm">viewckey</prop> </props> </property> </bean> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" /> <!-- The index controller. --> <bean name="indexController" class="org.springframework.web.servlet.mvc.ParameterizableViewController" p:viewName="index" /> </beans>
4.web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.1" 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"> <context-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/applicationContext.xml</param-value> </context-param> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <servlet> <servlet-name>dispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>2</load-on-startup> </servlet> <servlet-mapping> <servlet-name>dispatcher</servlet-name> <url-pattern>*.htm</url-pattern> </servlet-mapping> <session-config> <session-timeout> 30 </session-timeout> </session-config> <welcome-file-list> <welcome-file>redirect.jsp</welcome-file> </welcome-file-list> <jsp-config> </jsp-config> </web-app>
5.redirect.jsp
<%@page contentType="text/html" pageEncoding="UTF-8"%> <% response.sendRedirect("index.htm"); %>
There are default package with custom and controlling package classes.
6.default package
A. hibernate.cfg.xml
<?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.dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/demo?zeroDateTimeBehavior=convertToNull</property> <property name="hibernate.connection.username">root</property> <property name="hibernate.current_session_context_class">thread</property> <property name="hibernate.show_sql">true</property> <mapping resource="com/pojo/file/Springhibernet.hbm.xml"/> </session-factory> </hibernate-configuration>
B. hibernate.reveng.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-reverse-engineering PUBLIC "-//Hibernate/Hibernate Reverse Engineering DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-reverse-engineering-3.0.dtd"> <hibernate-reverse-engineering> <schema-selection match-catalog="demo"/> <table-filter match-name="springhibernet"/> </hibernate-reverse-engineering>
7. controlling package

1. This is the Bean class and hbm file package name is "com.pojo.file".

A. Springhibernet.java
package com.pojo.file; import java.util.Date; public class Springhibernet implements java.io.Serializable { private Long employeeId; private String firstname; private String lastname; private Date birthDate; private String cellPhone; public Springhibernet() { } public Springhibernet(Date birthDate, String cellPhone) { this.birthDate = birthDate; this.cellPhone = cellPhone; } public Springhibernet(String firstname, String lastname, Date birthDate, String cellPhone) { this.firstname = firstname; this.lastname = lastname; this.birthDate = birthDate; this.cellPhone = cellPhone; } public Long getEmployeeId() { return this.employeeId; } public void setEmployeeId(Long employeeId) { this.employeeId = employeeId; } public String getFirstname() { return this.firstname; } public void setFirstname(String firstname) { this.firstname = firstname; } public String getLastname() { return this.lastname; } public void setLastname(String lastname) { this.lastname = lastname; } public Date getBirthDate() { return this.birthDate; } public void setBirthDate(Date birthDate) { this.birthDate = birthDate; } public String getCellPhone() { return this.cellPhone; } public void setCellPhone(String cellPhone) { this.cellPhone = cellPhone; } }
B. Springhibernet.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <!-- Generated Sep 5, 2016 11:47:41 AM by Hibernate Tools 4.3.1 --> <hibernate-mapping> <class name="com.pojo.file.Springhibernet" table="springhibernet" catalog="demo" optimistic-lock="version"> <id name="employeeId" type="java.lang.Long"> <column name="employee_id" /> <generator class="identity" /> </id> <property name="firstname" type="string"> <column name="firstname" length="50" /> </property> <property name="lastname" type="string"> <column name="lastname" length="50" /> </property> <property name="birthDate" type="date"> <column name="birth_date" length="10" not-null="true" /> </property> <property name="cellPhone" type="string"> <column name="cell_phone" length="15" not-null="true" /> </property> </class> </hibernate-mapping>
c. HibernateUtil.java
package com.pojo.file; import org.hibernate.cfg.AnnotationConfiguration; import org.hibernate.SessionFactory; /** * Hibernate Utility class with a convenient method to get Session Factory * object. * * @author manoj kumar */ public class HibernateUtil { private static final SessionFactory sessionFactory; static { try { // Create the SessionFactory from standard (hibernate.cfg.xml) // config file. sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory(); } catch (Throwable ex) { // Log the exception. System.err.println("Initial SessionFactory creation failed." + ex); throw new ExceptionInInitializerError(ex); } } public static SessionFactory getSessionFactory() { return sessionFactory; } }
               2.  This is the view controlling package name is "com.spring.module".
A. view.java
package com.spring.module; import com.pojo.file.HibernateUtil; import org.springframework.web.servlet.mvc.SimpleFormController; import com.pojo.file.Springhibernet; import java.util.List; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.hibernate.Session; import org.springframework.web.servlet.ModelAndView; /** * * @author manoj kumar */ public class view extends SimpleFormController{ public view() { setCommandClass(Springhibernet.class); setCommandName("view"); } @Override public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception { ModelAndView mv=new ModelAndView("view"); String title="Spring and Hibernate Tutorial"; try { Session s=HibernateUtil.getSessionFactory().openSession(); s.beginTransaction(); List result=s.createQuery("From Springhibernet").list(); mv.addObject("view", result); s.getTransaction().commit(); } catch (Exception e) { e.printStackTrace(); } mv.addObject("message", title); return mv; } }
Web browser page index.jsp and view.jsp.
8.index.jsp
<%@page contentType="text/html" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Spring and Hibernate Tutorial</title> </head> <body> <p align="center"> <b>Hello! This is the default welcome page for a Spring and Hibernate Tutorial project.</b></p> <table align="center"> <tr><th> </th></tr> <th><a href="view.htm">View Information</a></th></tr> </table> </body> </html>





9. view.jsp

<%-- Document : view Created on : Sep 5, 2016, 10:53:07 AM Author : manoj kumar --%> <%@page contentType="text/html" pageEncoding="UTF-8"%> <%@taglib prefix="c" uri="http://java.sun.com/jstl/core_rt" %> <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>${message}</title> </head> <body> <p align="center"> <b>${message}</b></p> <table border="1" align="center"> <tr> <td>Employee Id</td> <td>Name</td> <td>Last Name</td> <td>DOB</td> <td>Mobil No.</td> </tr> <c:forEach items="${view}" var="view" > <tr> <td><c:out value="${view.employeeId}" /></td> <td><c:out value="${view.firstname}" /></td> <td><c:out value="${view.lastname}" /></td> <td><c:out value="${view.birthDate}" /></td> <td><c:out value="${view.cellPhone}" /></td> </tr> </c:forEach> </table> </body> </html>