Intro to Java Spring

What is Spring?

The Spring framework provides a set of libraries and tools for developing Java-based applications, including web applications, mobile apps, and microservices. It is one of the most popular Java frameworks as it allows the effective building of complex applications by providing production-ready features such as the dependency injection feature, aspect-oriented programming, transaction management, and data access. It also provides support for various Java technologies such as JavaServer Pages (JSP), Java Message Service (JMS), and Java Database Connectivity (JDBC).

In addition to the core Spring framework, other Spring frameworks extend its capabilities, such as Spring Boot, which makes it easier to build and deploy a Spring application, and Spring Cloud, which provides tools for building distributed systems. Spring has become a popular choice for professional Java development because of its ease of use, flexibility, extensive documentation, and community support.

Spring History 

The Spring framework for Java was created in 2002 by Rod Johnson, a Software developer who wanted to simplify the development of enterprise Java Spring applications. At the time, Java developers struggled with complex, heavy-weight frameworks that were difficult to work with and required a lot of boilerplate code.

The first version of Java Spring MVC was released in 2004, and it quickly gained popularity among Java developers. It was praised for its simplicity, modularity, and flexibility, and it soon became the de facto standard for building enterprise Java applications.

Over the years, Spring MVC has continued to evolve and grow, with new core features and capabilities added in each release making it one of the popular Java frameworks. In 2013, Spring was acquired by Pivotal, a software company formed by a joint venture between EMC, VMware, and General Electric.

Why Spring?

Several reasons you should consider using the Spring framework for Java development:

1. Simplifies development: Spring's key features make it easier and faster to develop enterprise Java applications. It also allows developers to focus on the business logic of their applications rather than worrying about low-level details such as database connections and transactions.
2. Modular and flexible: Spring framework is designed to be modular and flexible, allowing you to pick and choose the core capabilities you need for your application. This can help keep your application lightweight and easy to maintain.
3. Large community and ecosystem: Spring has a large and active community of developers and users, which means you can find many resources, documentation, and support online. In addition, many other projects build on top of Spring, such as Spring Boot and Spring Cloud, which can help extend its capabilities.
4. Integrates well with other Java technologies: Spring framework is designed to work well with other Java technologies, such as JavaServer Pages (JSP), Java Message Service (JMS), and Java Database Connectivity (JDBC). Integrating your Spring applications with other systems and technologies can make it easier.

As a result of this, many companies look to hire skilled Spring developers.

What Does a Spring Developer Do? 

A Java Spring developer is a software developer specializing in building enterprise Java applications using Spring's web framework. The responsibilities of a Spring developer can vary depending on the organization they work for and the specific Spring projects they are working on but typically include:

1. Designing and developing software applications: Spring framework developers are responsible for designing, developing, and unit testing software applications using the Spring framework. This includes writing code, creating and modifying database schemas, adding dependency injection, and integrating different application components.
2. Troubleshooting and debugging: When issues arise, Spring developers are responsible for identifying and resolving them. This can involve troubleshooting code, reviewing logs, and testing different scenarios to find the root cause of the problem.
3. Collaborating with other team members: Spring developers typically work in a team environment, so they must collaborate with other developers, designers, and project managers. This includes attending meetings, contributing to project planning, and communicating progress and status updates.
4. Staying up-to-date with new developments: Spring developers must stay up-to-date with any software development role. This includes learning about new features and capabilities of the Spring framework and new tools, languages, Spring Security, and technologies that can be used in conjunction with the Spring framework.

Overall, Spring developers are responsible for building high-quality software applications using the Spring framework while collaborating with other team members and staying up-to-date with new developments in the field.

How to Become a Spring Developer? 

Let's discuss some general steps you can take to become a Spring developer:

Learn Java and Spring

Spring is built on top of Java, so a good understanding of Java is essential. Start by learning the basics of Java programming, such as data types, control structures, and object-oriented programming. In addition to this, it is recommended to learn about HTML, CSS, and XML configuration. Once you grasp Java well, start learning the Spring framework. Dive deep into Spring Configuration, Spring batch, inversion of control (IOC), dependency injection, and Spring context. Many online resources are available, including official documentation, Spring Boot tutorials, and online courses.

Build Projects

Practice building projects using Java Spring. Start with simple applications with dependency injection, and gradually move on to more complex projects and start using Spring Security. Understand the underlying Spring framework and try creating standalone Spring applications. This will give you hands-on experience with the Spring and Spring Boot frameworks and help you develop your skills.

Learn Related Technologies

Spring MVC works well with other Java technologies, such as Hibernate for database access, JSP for web development, and Maven for project management. Learning these technologies can help you become a more well-rounded Spring developer.

Join the Community

Joining the Spring community can be a great way to learn from other developers and get involved in open-source projects. You can participate in forums, attend conferences, and contribute to the Spring framework.

Pursue Certifications

There are certification programs available for Spring, such as the Spring Security Professional Certification. Getting certified can help demonstrate your knowledge and expertise to potential employers.

Advantages of Spring

There are many advantages to using the Spring framework for Java development. Let's go over some of the key benefits:

Simplifies Development

Spring provides tools and features that make it easier and faster to develop enterprise Java applications. It simplifies common tasks, such as database access, security, and transaction management, allowing developers to focus on the business logic of their applications.

Modular and Flexible 

Spring is designed to be modular and flexible, allowing you to pick and choose the features you need for your application. This can help keep your application lightweight and easy to maintain.

Large Community and Ecosystem

Java Spring has a large and active community of developers and users, which means you can find many resources, documentation, Spring Boot tutorials, and support online. In addition, many other projects build on top of Spring, such as Java Spring Boot and Spring Cloud, which can help extend its capabilities.

Provides a Consistent Programming Model

Spring provides a consistent programming model that can be used across different application layers, from the data layer to the presentation layer. Coupled with dependency injection, this can help improve maintainability and make working with different developers and teams easier.

Promotes Best Practices

This Java framework promotes best practices for enterprise Java development, such as dependency injection, inversion of control (IOC), and separation of concerns. By following these best practices, you can build high-quality, maintainable applications that are easier to test and modify.

Installation of Spring Framework

Spring framework requires you to have Java 17 or higher. If you already have Java you can check your version by running:

java -version

Once, you’ve installed the latest version of Java, download the Spring framework from the official website. Once the download is complete, extract the downloaded files to a directory on your PC.

Next, Set up your development environment to work with the Spring framework. If you don't properly set your CLASSPATH variable in this directory, you'll have problems running your application. However, if you're using Eclipse, you won't need to set CLASSPATH because Eclipse will handle everything.

Components of Spring

Java Spring provides several components that developers can use to build web services. Here are some of the most commonly used Spring components:

Spring Core

The Spring container is the most basic component in the Spring framework. It provides the dependency injection (DI) mechanism, which allows developers to write loosely coupled code.

@Component
public class MyComponent {
    private final MyDependency myDependency;

    @Autowired
    public MyComponent(MyDependency myDependency) {
        this.myDependency = myDependency;
    }

    public void doSomething() {
        myDependency.doSomethingElse();
    }
}

@Component
public class MyDependency {
    public void doSomethingElse() {
        // do something
    }
}

This example gives an overview of dependency injection. The MyComponent class depends on the MyDependency class, which is injected using the @Autowired annotation. This allows MyComponent to call the doSomethingElse method on MyDependency without creating a new instance.

Spring MVC

The Spring MVC (Model-View-Controller) framework is used to build web applications. It provides a way to map HTTP requests to controllers and views.

@Controller
@RequestMapping("/hello")
public class HelloController {
    @GetMapping
    public String hello(Model model) {
        model.addAttribute("message", "Hello, world!");
        return "hello";
    }
}

In this example, the HelloController class is mapped to the /hello URL path using the @RequestMapping annotation. The hello method returns the name of the view (hello) and adds a message to the model, which is then displayed in the view.

Spring Data

Spring Data provides a set of abstractions for working with data stores. In addition, it supports a wide range of databases, including relational, NoSQL, and graph databases.

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    List<User> findByLastName(String lastName);
}

@Service
public class UserService {
    private final UserRepository userRepository;

    @Autowired
    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    public List<User> findUsersByLastName(String lastName) {
        return userRepository.findByLastName(lastName);
    }
}

In this example, the UserRepository interface extends the JpaRepository interface, which provides a set of methods for working with a database. The UserService class depends on UserRepository, which is injected using the @Autowired annotation. The findUsersByLastName method uses the findByLastName method provided by UserRepository to query the database and return a list of users.

These are just a few components available in the Java Spring framework. In addition, Spring provides a wide range of functionality, including security, testing, and messaging, making it a powerful and versatile tool for building web applications.

Development Best Practices

Use Dependency Injection

Dependency Injection (DI) is one of the core Spring framework features. As the name implies, dependency injection allows you to inject dependencies into your objects, making your code more modular and easier to test. With DI, you can easily swap out implementations of a dependency without changing the code that depends on it.

Use Java Spring Boot

Spring Boot is an opinionated framework built on top of the Spring framework. Java Spring Boot features provide a set of defaults and conventions that make it easy to get started with Spring development. If you learn Spring Boot, you can easily create standalone applications that are production-ready. So it is always a good idea to take a Spring Boot tutorial or two.

Use Spring Data for Data Access

Spring Data is a set of tools and frameworks for data access in the Spring framework. It provides a consistent way to interact with different data sources, including relational databases, NoSQL databases, and in-memory data stores. With these tools, you can easily write database queries and manage transactions.

Use Spring AOP for Cross-Cutting Concerns

Aspect-Oriented Programming (Spring AOP) is a programming design that allows you to modularize cross-cutting concerns, such as logging, security, and transaction management. With Spring AOP, you can easily add these concerns to your code without cluttering it with boilerplate code.

Use JUnit for Testing

JUnit is a popular testing framework for Java applications. With Spring, you can easily write tests for your code using JUnit. In addition, this application framework provides a set of testing annotations and utilities that make it easy to write unit and integration tests.

Use Continuous Integration and Deployment

Continuous Integration (CI) and Continuous Deployment (CD) are essential for modern software development. The Spring ecosystem lets you easily integrate your code with popular CI/CD tools like Jenkins, Travis CI, and CircleCI. This allows you to automate your build, test, and deployment process and ensure your code is always production-ready.