A complete boot camp for beginners who want to learn Spring Boot. In this course, you'll learn how we can create web services and cover all the topics of Spring Boot, Spring Framework, and many others. If you've some experience in Java and want to be a Software Engineer or Java Developer using Spring, you're on right way. Just read and practice, in the end of this course you'll have a great knowledge of Spring boot, a backend knowledge. Course outline: JPA, Hibernate, Spring, Spring Framework, H2 Database, PostgreSQL, MySQL. #SpringBoot #SpringFramwork #MySQL #PostgreSQL #MySQL #H2 #JPA/Hibernate #Webservices

1. A Complete Spring Boot Course for beginners
https://spring.io/
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Sufyan Sattar
Software Engineer
sufyan.sattar@tkxel.com

2. Course
Outline
Introduction to Spring Boot and Background
Web Services (SOAP and Restful)
JPA/Hibernate and Custom SQL Queries
H2 Database (In memory database)
PostgreSQL and MySQL
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3. Introduction to Spring Boot
 It is an application framework used for developing Enterprise Applications.
 It makes programming Java quicker, easier, and safer for everybody.
 It provides a flexible way to configure Java Beans, XML configurations, and Database Transactions.
It provides powerful batch processing and manages REST endpoints. In Spring Boot, everything is
auto-configured; no manual configurations are needed.
 Termimology:
 Spring Initializer (https://start.spring.io/)
 Starter Projects
 Auto Configuration
 Actuators
 Developer Tools (DevTools)
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4.  Setting up Spring Web projects was not easy
 Define Maven Dependencies and manage versions for the framework (spring web_mvc, Jackson)
 Define web.xml (src/main/webapp/WEB_INF/web.xml)
 Define front controller for spring framework (Dispatcher Servlets)
 Define a Spring content.xml (src/main/webapp/WEB_INF/todo_servlet.xml)
 Define all beans
 Define component scan
 Install Tomcat or another web server like Glassfish.
 Deploy and run the application in Tomcat
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World Before Spring Boot

5.  Spring Boot Starter Projects
 It helps you get the project up and running quickly.
 Web Applications (Spring boot starter web)
 Rest API (Spring boot starter web)
 Talk to database using JPA (spring boot starter data JPA)
 Talk to database using JDBC (spring boot starter JDBC)
 Spring Boot Auto Configurations
 It provides a basic configuration to run your app using the framework defined in maven dependencies.
 We can override our own configuration
 Auto configuration is decided based on which framework is in the classpath
 E.g. (spring boot starter web)
 Dispatch Servlet
 Embeded Servlets Container – Tomcat is the default server
 Default Error Page
 Bean to JSON conversion
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How does Spring Boot do its magic?

6.  Monitor and manage your application in your production.
 Provides a number of endpoints:-
 Beans – Complete the list of Spring beans in your app
 Health – Application health information
 Metrics – Application metrics
 Mapping – Details around Request Mapping
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Spring Boot - Actuators
 Increase developer productivity
 Save timing
 Only local machine or debug variant
Spring Boot - Dev Tools

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Spring Framework vs Spring Boot
 Spring Framework
 The Spring framework provides comprehensive infrastructure support for developing Java applications.
 It's packed with some nice features like Dependency Injection, and out-of-the-box modules like:
 Spring JDBC
 Spring MVC
 Spring Security
 Spring ORM
 Spring Test
 Spring Boot
 Spring Boot is basically an extension of the Spring framework, which eliminates the boilerplate configurations
required for setting up a Spring application.
 Here are just a few of the features in Spring Boot:
 Opinionated ‘starter' dependencies to simplify the build and application configuration
 Embeded Server to avoid complexity in application deployment
 Metrics, Health checks, and external configuration
 Automatic config for Spring functionality

8. Web Services
 Design for machine-to-machine or application-to-application interaction.
 Should be interoperable – Not platform dependent
 Should allow communication over a network
Web Service Definition
Request/Response Format Request Structure Response Structure Endpoint
(XML/JSON)
Note
 Dispatcher Servlets handle the request/response
 Spring boot auto configuration handle/configure dispatcher servlets
 Jackson converts the Java Bean to JSON and vice versa
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Web Service Task
 Social Media Application Usecase : User ---> Post
 Retrieve all users GetRequest /users
 Create a user PostRequest /users
 Retrieve a specific user GetRequest /users{id}
 Delete a user DeleteRequest /users{id}
1. Create a Controller. @RestController
2. Create methods for API and annotate with
1. @GetMapping
2. @PostMapping
3. @PutMapping
4. @DeleteMapping

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Web Service Topics
 HATEOAS (Hyper Media as the Engine of Application State)
 HATEOAS will add value to you API when used by client. The links provided by HATEOAS gives you the possibilities to
different parts (resources) of your API without needing to hardcore those links in your apps client code.
 We use WebMvcLinkBuilder and link any method/API of our
controller in the response.
 E.g. I request http://localhost:8080/jpa/users/1/posts/1
 Exception Handling
 Give a proper response to the user when an exception occurs with the status code.
 We can use ResponseEntityExceptionHandler to provide centralized exception handling across all @RequestMapping
methods through @ExceptionHandler methods.

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Web Service Topics
 Validation for Rest API
 We can add @Valid to validate our request
 @Sized(min=2) @Email @Past
 We just place annotation to the variable
 Internationalization for Restful Services
 We create different resources file w.r.t languages e.g: messages_fr.properties.
 In messages.properties file we write string in different language.
 Content Negotiation
 We can implement XML support in out Restful API.
 Client will sent Accept Header with application/xml value.

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Web Service Topics
 Swagger UI
 baseurl/swagger-ui/index.html
 OpenAPI create all the documentation of your Restful API in our application
 Swagger UI gets that data and represents in GUI
 OpenAPI definition: baseurl/v3/api-docs
 Monitory API with Spring Boot Actuators
 base_url/actuator
 We can manual configuration by adding some lines
 in application.properties file
 HAL Explorer
 Visualizing all API
 Its show all links in visual format
 You can also see HATEOAS links in visual formats
 base_url/explorer/

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Web Service Topics
 Filtering
 Static Filtering
 Just place @JsonIgnore above the variable
 You can also place above class name and add multiple parameter name
 Dynamic Filtering
 When you hide/show data in response w.r.t to response
 We use SimpleBeanPropertyFilter, FilterProvider, and MappingJacksonValue
 Versioning
 Url versioning
 Params versioning
 Customer Header versioning
 Produces versioning (mine-type versioning)

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Web Service Topics
 Security
 After Enable security web services will return 401 unauthorized status.
 Request all API with basic Auth (username=user and password=from console)
 Add configuration for static password not change when server restart
 security.username=username , security.password=password

15. JPA/Hibernate and Custom Query
 JPA is the specification and define the way to manage relational database using Java Objects
 Hibernate is the implementation of Java Persistence API. It is the ORM tool to persist Java objects
into relational database
 Implementation/Annotations:
 @Entity
 @Table(name=“employee”)
 @Column(name=“first_name”)
 EmptyConstructor
 All Argument Constructor
 Setter/Getter
 @OneToMany(mappedBy=“user”, cascade=Cascade.ALL)
 @ManyToOne()
 @JoinColoum
 @Id
 @GeneratedValue(strategy= GenerationType.IDENTITY)
 @Repository (interface UserRepo implement JpaRepository<User, Integer>)
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16. JPA/Hibernate and Custom Query
 JPA Repository:
 Its interface having default storage methods like save(), findAll(); findBtId(), DeleteById() etc.
 Its provides us the ORM for storing data into relational database.
 We can also write custom query for fetching data from database.
 JPA provided us @Query annotation.
 Create interface and implement JpaRepository<Object, Integer>)
 Inside repo you can write function and custom query
 Custom Query:
@Query(“SELECT * FROM posts WHERE user_id=:user_id AND id=:post_id”, nativeQuery=true)
 Post getPostDetailsOfSpecifcUser(
@Param(“user_id”) Integer user_id,
@Param(“post_id”) Integer post_id
);
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17. H2 Database
 H2 is inmemory database provided by Spring Boot.
 H2 database name randomly generated each time you restart the run or run application.
 We can make it constant by manual configuration:
 Spring.datasource.url=“jdbc:h2:mem:mytestdb”
 Sometime we need more fined grained control over tha database alterations and that why we create
data.sql and schema.sql
 data.sql:- We rely on default schema created by Hibernate/JPA. We add data into data.sql by writing SQL
queries into data.sql file
 schema.sql:- We don`t rely on default schema creation mechanism. We create own schema i.e table and
coloums etc. Spring will pickup this file and create schema
 Note: Script base initialization i.e through data.sql and schema.sql, and hibernate default initialization
together can cause some issues.
 We disable hibernate automatic schema creations with manual configuration.
 spring.jpa.hibernate.ddl-auto=none
 If you want to use both hibernate automatic creation schema and script based schema creation and data
population. You can use
 spring.jpa.defer-datasource-initialization=true
 Script base initialization is perform by default only for embeded databases.
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18. PostgreSQL and MySQL with Spring Boot
 Configuration with PostgreSQL
 spring.datasource.url=jdbc:postgresql://localhost:5432/employees
 spring.datasource.username=postgres
 spring.datasource.password=admin
 spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.PostgreSQLDialect
 Configuration with MySQL
 spring.datasource.url=jdbc:mysql://localhost:3306/employees
 spring.datasource.username=root
 spring.datasource.password=admin
 spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5InnoDBDialect
 spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
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