Spring

What is Spring?

Spring is a powerful, lightweight application framework designed for the Enterprise Java platform. It offers a complete suite for building applications, from configuration, security, web applications, data access, messaging, and more.

Setting Up a Spring Project

A Spring Boot project can be set up by using Spring Initializer, an online tool that allows to configure the basic details of your project.

// Use Spring Initializer (start.spring.io) to set up a project. Select the desired specifications and generate the project.

Dependency Injection

Dependency Injection (DI) is a pattern that decouples the dependencies of an application. Spring provides DI via either XML configuration or annotations.

@Autowired
private EmployeeService employeeService;

Spring Beans

Spring Beans are the objects that form the backbone of the application. They are managed by the Spring IoC container.

@Component
public class Employee {...}

Spring Data JPA

Spring Data JPA, part of the larger Spring Data family, makes it easy to implement JPA-based repositories. This module deals with enhanced support for JPA-based data access layers.

@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long> {...}

Transaction Management

Spring provides a consistent transaction management interface that can scale down to a local transaction (using a single database, for example) and scale up to global transactions (using JTA, for example).

@Transactional
public void performOperation() {...}

Controllers and Views

Spring MVC offers annotations to map requests and to express request mapping conditions.

@Controller
public class EmployeeController {
	@GetMapping('/employee')
	public String getEmployee(Model model) {...}
}

Form Handling

Spring MVC supports form handling and provides all the necessary configuration via annotations. You can bind form elements to Model objects.

@PostMapping('/employee')
public String saveEmployee(@ModelAttribute('employee') Employee employee, BindingResult result, Model model) {...}

Security Configuration

Spring Security is a powerful and highly customizable authentication and access-control framework. It provides protection against attacks like session fixation, clickjacking, cross-site request forgery, etc.

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {...}

Authentication and Authorization

Spring Security provides authentication and authorization features, protecting application from unauthorized access.

@PreAuthorize('hasRole('ROLE_ADMIN')')
public String securedMethod() {...}