Java Frameworks and Libraries

Getting Started with Spring and Spring Boot

Spring and Spring Boot are among the most popular Java frameworks for building modern web applications and microservices. Spring provides a comprehensive programming and configuration model, while Spring Boot simplifies Spring application development by offering conventions and defaults.

1. Introduction to Spring Framework

Spring Framework is a powerful, lightweight solution for building enterprise applications. It provides extensive infrastructure support for developing Java applications. Spring handles the infrastructure so developers can focus on application logic.

Core Features:
- Inversion of Control (IoC): Spring manages your application’s components, promoting loose coupling through dependency injection.
- Aspect-Oriented Programming (AOP): Allows defining cross-cutting concerns that affect the whole application, such as logging and transaction management.
- Data Access: Simplifies JDBC operations, manages transactions, and integrates with popular ORM frameworks like Hibernate.
- Transaction Management: Unifies several transaction management APIs and coordinates transactions for Java objects.
- Model-View-Controller (MVC): A configurable MVC framework for building web applications.

2. Spring Boot Introduction

Spring Boot makes it easy to create stand-alone, production-grade Spring-based applications. It takes an opinionated view of the Spring platform, which simplifies the configuration and deployment process.

Core Features:
- Auto-configuration: Automatically configures your Spring application based on the jar dependencies you added.
- Standalone: Creates standalone Spring applications with embedded Tomcat, Jetty, or Undertow, eliminating the need for deploying WAR files.
- Opinionated Defaults: Offers a range of configuration options to customize your application.
- Actuator: Provides built-in endpoints for monitoring and managing your application in production.

3. Getting Started with Spring

To start using Spring, you typically set up a project with build automation tools like Maven or Gradle that manage dependencies.

Dependency Management: Add Spring dependencies to your pom.xml (Maven) or build.gradle (Gradle).

<!– Maven example –>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.3.8</version>
</dependency>
</dependencies>

Configuration: Define your application components and their dependencies in an XML file or using annotations.

@Configuration
public class AppConfig {
@Bean
public MyBean myBean() {
return new MyBean();
}
}

Running: Load your configuration via ApplicationContext to manage the lifecycle of your beans.

ApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
MyBean myBean = context.getBean(MyBean.class);

4. Getting Started with Spring Boot

Creating a new Spring Boot project is straightforward with the Spring Initializr web tool.

Setup: Go to https://start.spring.io/, choose your project options, and generate your project.
Developing Your Application: Unzip and import your project into your IDE. Add your business logic:

@SpringBootApplication
public class MyApp {
public static void main(String[] args) {
SpringApplication.run(MyApp.class, args);
}
}

Configuration: Spring Boot uses an application.properties or application.yml file to configure properties.

# application.properties
server.port=8080
spring.datasource.url=jdbc:mysql://localhost/test

Running: Run your application either from the IDE or using the command line (./mvnw spring-boot:run for Maven projects).

5. Conclusion

Spring and Spring Boot are powerful frameworks that significantly ease the development of Java applications. Spring provides deep functionality for comprehensive application development, while Spring Boot simplifies the development process with its convention-over-configuration approach, making it easier to start and scale applications. Whether building simple APIs or complex enterprise systems, Spring and Spring Boot offer a robust foundation for Java developers.

Web Development with Java EE or Jakarta EE

Java EE (Enterprise Edition), now known as Jakarta EE under the Eclipse Foundation’s stewardship, is a set of specifications that extend the Java SE (Standard Edition) with specifications for enterprise features such as distributed computing and web services. Jakarta EE offers a robust platform for developing and running scalable, multi-tiered, reliable, and secure enterprise-level applications.

1. Overview of Jakarta EE

Jakarta EE provides a comprehensive environment for developing and running enterprise applications and services. This platform builds upon the solid foundation of Java SE and offers APIs and runtime environments for developing and deploying applications on servers.

2. Core Components of Jakarta EE

Jakarta EE encompasses a wide range of technologies and APIs that cater to various aspects of enterprise application development. Key components include:

Servlet API: Allows the definition of HTTP-specific servlet classes. A servlet is a Java programming language class used to extend the capabilities of servers that host applications accessed by means of a request-response programming model.
JavaServer Pages (JSP): Simplifies the development of dynamic web content. JSPs embed Java code in HTML pages, which are then compiled into servlets by the server during runtime.
JavaServer Faces (JSF): A framework for building server-side user interfaces. It provides a component-based approach to developing Java web applications, making it easier to construct complex user interfaces.
Java Persistence API (JPA): Manages relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition.
Enterprise JavaBeans (EJB): A managed, server-side component architecture for modular construction of enterprise applications.
Contexts and Dependency Injection (CDI): Manages dependencies among classes and integrates different components by unifying the EJB and JSF models with modern Java constructs, such as annotations.
Java Message Service (JMS): A messaging standard that allows application components based on Jakarta EE to create, send, receive, and read messages.

3. Developing a Simple Web Application with Jakarta EE

Here’s a brief guide to setting up a simple web application using Jakarta EE components, focusing on Servlets and JSP:

Environment Setup: Ensure you have JDK installed and choose a Jakarta EE-compatible server such as Apache Tomcat, Payara Server, or WildFly for deployment.
Project Structure: Create a new Jakarta EE project in your IDE (such as Eclipse, IntelliJ IDEA, or NetBeans), which supports Jakarta EE. Structure your project to include directories for sources (src), web content (WebContent), and libraries (lib).
Writing a Servlet:

@WebServlet(“/greeting”)
public class GreetingServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType(“text/html”);
response.getWriter().print(“<html><body><h2>Hello from Jakarta EE</h2></body></html>”);
}
}

Developing JSP Pages: Create a JSP file in the WebContent directory.

<%– index.jsp –%>
<html>
<body>
<h1>Welcome to Jakarta EE Web Development</h1>
<form action=”greeting”>
<input type=”submit” value=”Show Greeting”/>
</form>
</body>
</html>

Deployment Descriptor: Configure your application’s deployment settings in the WEB-INF/web.xml file, although many modern servlet containers allow you to omit this if using annotations.
Building and Running: Build your application using Maven or Gradle and deploy it to your chosen server. Ensure the server is configured correctly to handle Jakarta EE applications.

4. Advantages of Using Jakarta EE

Simplicity in Complexity: Jakarta EE simplifies complex server-side development by providing reusable components and standard APIs.
Enterprise Grade: Offers robustness, scalability, and distributed multi-tiered applications support.
Community and Standards Driven: Being open-source and driven by community contributions, it evolves to meet the changing needs of enterprise application development.

Jakarta EE continues to be a strong foundation for developing dynamic, scalable, and secure web applications and services in Java. Whether you are maintaining legacy applications or building new services, understanding Jakarta EE is crucial for any enterprise Java developer.

Exploring Libraries like Apache Commons, Guava, and More

Java developers often rely on external libraries to simplify common programming tasks, enhance performance, and improve code readability. Among these, Apache Commons and Google Guava stand out due to their wide utility and robust performance. Let’s explore these libraries, along with some additional ones that are valuable across various Java projects.

1. Apache Commons

Apache Commons is a project of the Apache Software Foundation, designed to provide reusable open-source Java components. The Commons project consists of three parts: Commons Proper, Commons Sandbox, and Commons Dormant. Here, we focus on Commons Proper, which includes a variety of widely used libraries.

Commons Lang: Provides extra functionality for classes in java.lang, such as enhanced string manipulation, number creation, and date manipulation.

StringEscapeUtils.escapeHtml4(“special characters: &<>”); // Escapes HTML characters

Commons IO: Simplifies IO operations with utilities to work with streams, readers, writers, and files.

FileUtils.readFileToString(new File(“myfile.txt”), StandardCharsets.UTF_8); // Reads file into a string

Commons Collections: Offers new interfaces and implementations for collections, including bidirectional maps, bag, and buffer types.

BidiMap<String, Integer> bidiMap = new DualHashBidiMap<>();
bidiMap.put(“One”, 1);

2. Google Guava

Guava by Google is a set of core libraries that includes new collection types (such as multimap and multiset), immutable collections, a graph library, utilities for caching, support for functional programming, and much more.

Collections: Guava introduces collection types that are not native to the Java SDK.

Multimap<String, Integer> multimap = ArrayListMultimap.create();
multimap.put(“Key”, 1);
multimap.put(“Key”, 2);

Utilities: Includes utilities for hashing, concurrency, reflection, string processing, I/O, and more.

Joiner.on(“, “).skipNulls().join(“Harry”, null, “Ron”, “Hermione”); // “Harry, Ron, Hermione”

Caching: Guava provides a powerful, in-memory cache mechanism that is highly customizable.

Cache<String, String> cache = CacheBuilder.newBuilder().maximumSize(100).expireAfterWrite(10, TimeUnit.MINUTES).build();
cache.put(“key”, “value”);
String value = cache.getIfPresent(“key”);

3. Other Useful Libraries

Joda-Time: (Now largely supplanted by the Java 8 java.time package) Provides a quality replacement for the Java date and time classes.

DateTime dt = new DateTime();
DateTime plusPeriod = dt.plus(Period.days(1)); // Adds a day

SLF4J/Logback: Logging frameworks that offer a logging API (SLF4J) and an implementation of that API (Logback).

Logger logger = LoggerFactory.getLogger(MyClass.class);
logger.info(“Log information”);

Jackson: A high-performance JSON processor for serializing and deserializing JSON data.

ObjectMapper mapper = new ObjectMapper();
String jsonString = mapper.writeValueAsString(myObject); // Serializes object to JSON
MyObject obj = mapper.readValue(jsonString, MyObject.class); // Deserializes JSON to object

4. Advantages of Using Libraries

Efficiency: Libraries like Apache Commons and Guava have been optimized for performance and provide solutions to common problems that are more efficient than custom-built code.
Readability: Using well-known libraries can make your code easier to understand for other developers who are already familiar with these libraries.
Reliability: These libraries are extensively tested and used in thousands of applications, which helps in ensuring their reliability and bug-free operation.

Integrating these libraries into your Java projects can significantly reduce the amount of boilerplate code you need to write and maintain, thereby increasing productivity and allowing you to focus on application-specific logic.