SpringBoot workshop @ PUC SE Day 2019

1. SpringBoot

2. About us
jneis
josue@townsq.com.br
Josué
Neis
Software
Architect
matheuswanted
matheus.santos@townsq.com.br
Matheus
Santos
Software
Engineer

3. Agenda
- Java and Spring History
- Spring Framework
- SpringBoot
- IoC and DI
- Spring MVC
- Spring Data
- Next steps

4. History
J2EE 1.2
Servlet
EJB, JSP, JTA, JMS
J2SE 1.2
Collections
Swing
1996
1997
1998
1999
J2SE 1.1
Java Beans
JDK 1.0

5. Spring 1.0
J2EE 1.4
JAX-WS
JAX-RPC
2001
2002
2003
2004
interface21
J2EE 1.3
JAXP

6. Java EE 5
JPA
JAXB (binding)
2005
2006
2006
2007J2SE 5.0
Annotations
Generics
Spring 2.0
XML config
Spring 2.5
Annotation config

7. Java SE 8
Streams
Optional
Lambda expressions
Functional interfaces
2009
2012
2014
2014Java EE 6
JAX-RS (REST)
CDI (Context and DI)
Bean Validation
Interceptors (AOP)
Spring 3.2
Java config
Spring Boot
Spring 4.0
Java 8
Java EE 7
JSON

8. Java SE 10
Type inference (local vars)
2017
2017
2018
Java SE 9
Reactive Streams
Spring Boot 2.0
Spring 5.0
Java SE 11
SE-Day
2019

9. Spring Framework
- OS application framework
- Modular architecture
- Containers: application context, bean factory
- IoC: bean lifecycle management and DI
- AOP: cross-cutting concerns
- MVC: web applications and RESTful services
- Data access: JDBC, ORM, no-SQL
- Transaction management
- Security: authentication and authorization
- Messaging
- Testing

10. WebData Access & Integration
Core Container
Beans Core Context SpEL
Test
AOP Aspects Instrumentation Messaging
JDBC ORM
JMS Transactions
Servlet
WebSocket

11. compile group: 'org.springframework', name: 'spring-aop', version: '5.1.7.RELEASE'
compile group: 'org.springframework', name: 'spring-beans', version: '5.1.7.RELEASE'
compile group: 'org.springframework', name: 'spring-context', version: '5.1.7.RELEASE'
compile group: 'org.springframework', name: 'spring-core', version: '5.1.7.RELEASE'
compile group: 'org.springframework', name: 'spring-web', version: '5.1.7.RELEASE'
compile group: 'org.springframework', name: 'spring-webmvc', version: '5.1.7.RELEASE'
compile group: 'org.springframework.data', name: 'spring-data-jpa', version: '2.1.6.RELEASE'
compile group: 'com.fasterxml.jackson.core', name: 'jackson-core', version: '2.9.5'
compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.9.5'
compile group: 'com.fasterxml.jackson.core', name: 'jackson-annotations', version: '2.9.5'
compile group: 'com.fasterxml.jackson.jaxrs', name: 'jackson-jaxrs-json-provider', version: '2.9.5'
compile group: 'ch.qos.logback', name: 'logback-classic', version: '1.2.1'
compile group: 'org.slf4j', name: 'slf4j-api', version: '1.7.25'
compile group: 'org.slf4j', name: 'log4j-over-slf4j', version: '1.7.25'
testCompile group: 'org.springframework', name: 'spring-test', version: '5.1.7.RELEASE'
testCompile group: 'org.mockito', name: 'mockito-core', version: '2.21.0'
testCompile group: 'org.assertj', name: 'assertj-core', version: '3.11.0'
Spring Modules

12. SpringBoot
- Convention over configuration solution
- Standalone applications (JAR)
- Embedded application servers (no WAR)
- Simplified and auto configuration
- Starters
- Production-ready features
- Metrics
- Health check
- Externalized config
- No code generation
- No XML config required

13. plugins {
id 'org.springframework.boot' version '2.1.4.RELEASE'
}
apply plugin: 'io.spring.dependency-management'
compile group: 'org.springframework.boot', name: 'spring-boot-starter-data-jpa'
compile group: 'org.springframework.boot', name: 'spring-boot-starter-web'
testCompile group: 'org.springframework.boot', name: 'spring-boot-starter-test'
Starters
Spring Initializr

14. IoC & DI
- Inversion of Control
- Creationg of objects is transferred to a container or framework
- Decouples execution of tasks from their implementations
- Improves modularity (different implementations)
- Improves testability (isolating and mocking components)
- Dependency Injection
- Pattern that implements IoC principle
- Control being inverted is setting of objects' dependencies

15. public class UserService {
private final UserRepository repository;
public UserService() {
this.repository = new UserRepositoryImpl();
}
}
public class UserService {
private final UserRepository repository;
public UserService(UserRepository repository) {
this.repository = repository;
}
}
IoC & DI

16. Spring Container
Spring Container
Bean
Bean
Bean
Bean
Bean
Bean
Bean
Object
Object
Object
Object

17. BeanFactory & ApplicationContext
- BeanFactory
- Container for managing beans
- Resolve object graphs
- XML vs Annotation-based DI
- Component scanning
- ApplicationContext
- Central interface for configuration
- Builds on top of BeanFactory
- Loads file resources
- Publishes lifecycle events to
registered listeners
- Resolves messages for
internationalization

18. XML vs Annotation-based DI
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="<tl;dr>"
xmlns:xsi="<tl;dr>"
xmlns:context="<tl;dr>"
xsi:schemaLocation="<tl;dr>">
<bean id="userRepository"
class="io.townsq.es.day.UserRepositoryImpl"/>
<bean id="userService"
class="io.townsq.es.day.UserService">
<constructor-arg ref="userRepository"/>
</bean>
</beans>
@Configuration
public class BeanConfiguration {
@Bean
public UserRepository userRepository() {
return new UserRepositoryImpl();
}
@Bean
public UserService userService(UserRepository repo) {
return new UserService(repo);
}
}

19. Component Scanning & Auto-wiring
@Repository
public class UserRepositoryImpl implements UserRepository {
}
@Service
public class UserService {
private final UserRepository repository;
@Autowired
public UserService(UserRepository repository) {
this.repository = repository;
}
}

20. Spring Container
Spring
Container
Configuration
Metadata
XML-based
Annotation-based
Java-based
Read dependency
and configuration
Create dependency objects
and inject them
Business
Objects

21. Core Components
WebData Access & Integration
Core Container
Beans Core Context SpEL
Test
AOP Aspects Instrumentation Messaging
JDBC ORM
JMS Transactions
Servlet
WebSocket

22. Java Servlet
- Java class that
- Handles and processes requests
- Replies a response back
- Managed by Servlet containers
- Application servers
Web Server
JVM
Servlet
Container
Servlet
init()
service()
destroy()
Thread A
Thread B
Request to
Server

23. HTTP Servlet
@WebServlet(urlPatterns = "/users/*")
public class UserServlet extends HttpServlet {
private final UserService userService = new UserService(new UserRepository() {});
private final ObjectMapper mapper = new ObjectMapper();
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
String userId = request.getPathInfo().split("/")[1];
User user = userService.getUserById(userId);
response.setContentType("application/json");
response.getWriter().print(mapper.writeValueAsString(user));
response.getWriter().flush();
}
}

24. MVC in JEE
Client
Controller
Model
View
Request processing
Data validation
Business logic
Data manipulation
Response generation
Rendering
Database
Servlet
JSP
Bean
Request
Response
Browser

25. Spring MVC
- Web framework built on top of Servlet API
- Request routing and handling
- Object marshalling and validation
- Error handling
Controller
Model
View
Endpoints
JSON
Services
Database
Repositories

26. Controller @RestController
@RequestMapping("/users")
public class UserController {
@GetMapping("/{userId}")
public User getUserById(@PathVariable Integer userId) {
return service.getUserById(userId);
}
@PostMapping
@ResponseStatus(HttpStatus.CREATED)
public User createUser(@RequestBody User user) {
return service.createUser(user);
}
@GetMapping
public Collection<User> listUserByLastName(@RequestParam String lastName) {
return service.listUserByLastName(lastName);
}
}

27. Error Handling
@RestControllerAdvice
public class ErrorHandler {
@ExceptionHandler(IllegalArgumentException.class)
@ResponseStatus(HttpStatus.BAD_REQUEST)
public ErrorMessage handle(IllegalArgumentException exception) {
return new ErrorMessage(exception.getMessage());
}
}

28. JPA
- Specification that describes management of relational data
- Entities:
- Lighweight Java class whose state is persisted to a table in a relational database
- Implementations:
- Hibernate, TopLink, OpenJPA, Spring Data JPA

29. ORM
CREATE TABLE users (
id INT AUTO_INCREMENT PRIMARY KEY,
email VARCHAR(250) NOT NULL,
first_name VARCHAR(250) NOT NULL,
last_name VARCHAR(250) NOT NULL,
birth_date DATE NOT NULL
);
@Entity
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
@Column(nullable = false, unique = true)
private String email;
private String firstName;
private String lastName;
private LocalDate birthDate;
}

30. Hibernate
public class UserDao {
public User getById(Integer id) {
SessionFactory factory = HibernateUtil.getSessionFactory();
Session session = factory.openSession();
User user = session.get(User.class, id);
session.close();
return user;
}
}

31. Spring Data JPA
- Collection of default interfaces that gives
- Most common CRUD operations
- Sorting and paginating features
- Automatic custom querying
- Query DSL for extending query capabilities
- Custom querying with named queries

32. JPA with Spring Data
public interface UserRepository extends CrudRepository<User, Integer> {
Optional<User> findByEmail(String email);
Collection<User> findAllByLastName(String lastName);
}
public class UserService {
public void doSomething() {
Collection<User> users = repository.findAllByLastName("Banner");
Optional<User> user1 = repository.findByEmail("banner@townsq.io");
Iterable<User> all = repository.findAll();
Optional<User> user2 = repository.findById(1);
User saved = repository.save(new User());
repository.deleteById(2);
}
}

33. Next Steps
- Spring Security
- Customizable
- Authentication
- Authorization (access control)
- Spring Data with No-SQL
- Mongo
- ElasticSearch
- Cassandra
- Redis
- Spring Webflux
- Functional routing and handling
- Reactive components
- Event loop concurrency model
- Netty
- Reactor

34. Next Steps
- Spring Cloud
- Cloud-native applications
- Microservices
- Netflix OSS
- Externalized configuration
- Service discovery
- Gateway
- Resilience
- Streams
- Spring with other JVM langs
- Groovy
- Kotlin

35. Thank you all!
townsq.com.br/trabalhe-conosco
Code is available on:
github.com/townsquad/seday-springboot
Further contact:
josue@townsq.com.br
matheus.santos@townsq.com.br