It's also most up-to-date resource and covers changes on recent Java versions up to Java All you need is an internet connection to download these books on your computer, laptop, iPhone, or Android smartphone. Many Thanks to O'Rilley who has published an introductory book on Java 8, titled with Introducing Java 8, A quick start guide to lambda expressions and streams.
The author Raoul-Gabriel Urma, who is also an author of one of the best seller book of last year, Java 8 in Action , explains how improved code readability and support for multicore processors were the prime movers behind Java 8 features.
No doubt an excellent guide for any Java programmer willing to learn Java 8 by himself. If you follow examples given int his book, you will learn lambdas and Streams in real quick time.
There is also a free course on Udemy - Java 8 Functional Programming: Lambda Expressions Quickly , which is great for learning lambda expression, Stream API, and several functional programming concepts like map, flatmap, reduce introduced in Java 8. You don't need to pay anything for that, all you need is a Udemy account to access that course.
Object-Oriented vs. Since Java 8 is now support some of the functional programming concepts, like lambda expressions, map, flatmap, reduce, etc, it becomes crucial to learn how to work together in both OOP and FP at the same time.
Java technologist Richard Warburton, the author of Java: JSON Fundamentals and several other courses on Pluralsight, discusses similarities between these programming paradigms and points out that both FP and OOP are actually moving closer toward each another. Again, it's free and you don't need to pay a single cent, all you need a Udemy account to access this course.
Once you join the course, you can also access it for a life time. It is no more the fancy language of developers, but it has now become the mainstream of any application development in the world. The use of Java in Android has taken Java into the even more larger domain This book will take you to journey of Java programming language starting from very first version to the current Java 8 version.
Benjamins Evans, author of the modern Java book, the Well-grounded Java Developer will explain to you the design decision was taken at the start, like making it platform independent and always keeping it backward compatible and how they paid off. You have to deploy code, configuration, database changes, file systems changes, etc. Though this is the tried and tested approach and working well for a long time, it can be improved.
If you need a free course, you can also check out Docker for beginners course on Udemy, again, it's completely free and more than 10, students have already enrolled in this course.
In this course, you will learn the basics of Docker like what is Docker and what is container and how they help developers. You will also learn how to create a Docker image and run your application on the Docker container.
Since Docker is an extremely important tool for Java developer, I strongly suggest you learn Docker. Christian outlines both the benefits and drawbacks of Microservices and explains to them how to implement them using popular frameworks like DropWizard and Spring Boot.
This free Java book is full of useful examples. If you don't know you can take all Coursera courses for free. You only need to pay when you need a Certificate. If you need online courses, you can check this list of Spring Microservice courses for Java developers. Filled with a lot of samples but non-trivial examples of implementing different data structures, e.
This tutorial is aimed to provide dependency injection example in Spring framework with both annotation based configuration and XML based configuration. The tutorial also include JUnit test program to validate the implementation.
The tutorial explains about different types of Advice with simple program. This tutorial is aimed to explain the core concepts of Spring IoC container and Spring Bean with example programs. The tutorial also explains about Spring Bean, Spring Bean scopes, different ways to configure spring bean — XML, annotation, java-based through an example project.
This tutorial explains about different types of auto wiring with an example project. Spring Beans are the most important part of any Spring application.
Spring ApplicationContext is responsible to initialize the Spring Beans defined in spring bean configuration file. Spring framework also support PostConstruct and PreDestroy annotations for defining post-init and pre-destroy methods.
These annotations are part of javax. You will also learn about Spring Aware interfaces that you can use to inject Servlet API objects into the spring bean. Spring WebFlux is the new module introduced in Spring 5. Spring WebFlux is the first step towards the reactive programming model in spring framework.
Spring Data makes it easier to create Spring driven applications that use new ways to access data, such as non-relational databases, map-reduction frameworks, cloud services, as well as well-advanced relational database support. Spring Service annotation is a specialization of Component annotation. Spring Service annotation can be applied only to classes. It is used to mark the class as a service provider. Spring Component annotation is used to denote a class as Component. It means that the Spring framework will autodetect these classes for dependency injection when annotation-based configuration and classpath scanning is used.
Spring RestController annotation is a convenience annotation that is itself annotated with Controller and ResponseBody. This annotation is applied to a class to mark it as a request handler. Spring Controller annotation is a specialization of Component annotation. Spring Controller annotation is typically used in combination with annotated handler methods based on the RequestMapping annotation. Spring Repository annotation is used to indicate that the class provides the mechanism for storage, retrieval, search, update and delete operation on objects.
Spring Configuration annotation is part of the spring core framework. Spring Configuration annotation indicates that the class has Bean definition methods. So Spring container can process the class and generate Spring Beans to be used in the application.
Spring Value annotation is used to assign default values to variables and method arguments. We can read spring environment variables as well as system variables using Value annotation.
Spring PropertySource annotation is used to provide properties file to Spring Environment. This annotation is used with Configuration classes. When we annotate a method in Spring Bean with PostConstruct annotation, it gets executed after the spring bean is initialized.
When we annotate a Spring Bean method with PreDestroy annotation, it gets called when bean instance is getting removed from the context. Spring Async annotation allows us to create asynchronous methods in spring.
Spring Boot SpringBootApplication annotation is used to mark a configuration class that declares one or more Bean methods and also triggers auto-configuration and component scanning. Spring Boot SpringApplication class is used to bootstrap and launch a Spring application from a Java main method.
Spring Boot Actuator Endpoints lets us monitor and interact with our application. Spring Actuator is a Spring Boot sub-module and provides built-in endpoints that we can enable and disable for our application. Spring MVC modules help us in creating java based web applications. This tutorial explains all the different parts of the application that are required to configure our application to return JSON response and implement Rest API.
This tutorial explains how easily we can support both of them using simple configurations. This tutorial is aimed to provide an understanding of how different components are configured with an example of upload single and multiple files. Apr 01, PM org. You can uncomment the code to get bean of type MyEmployeeService and confirm that output will be similar and follow all the points mentioned above.
Spring Aware Interfaces Sometimes we need Spring Framework objects in our beans to perform some operations, for example reading ServletConfig and ServletContext parameters or to know the bean definitions loaded by the ApplicationContext. Aware is the root marker interface for all these Aware interfaces. Then spring context uses setter-based dependency injection to inject the corresponding objects in the bean and make it available for our use.
Spring Aware interfaces are similar to servlet listeners with callback methods and implementing observer design pattern. Arrays; import org. BeansException; import org. BeanClassLoaderAware; import org. BeanFactory; import org. BeanFactoryAware; import org. BeanNameAware; import org. ApplicationContext; import org.
ApplicationContextAware; import org. ApplicationEventPublisher; import org. ApplicationEventPublisherAware; import org. EnvironmentAware; import org. ResourceLoaderAware; import org. ImportAware; import org. Environment; import org. Resource; import org. ResourceLoader; import org. We have already see how Spring Dependency Injection works, today we will look into the core concepts of Aspect Oriented Programming and how we can implement it using Spring Framework.
Aspect Oriented Programming Overview Most of the enterprise applications have some common crosscutting concerns that is applicable for different types of Objects and modules. Some of the common crosscutting concerns are logging, transaction management, data validation etc. In Object Oriented Programming, modularity of application is achieved by Classes whereas in Aspect Oriented Programming application modularity is achieved by Aspects and they are configured to cut across different classes.
For example, we can have a separate class for logging but again the functional classes will have to call these methods to achieve logging across the application.
Join Point: A join point is the specific point in the application such as method execution, exception handling, changing object variable values etc. In Spring AOP a join points is always the execution of a method. Advice: Advices are actions taken for a particular join point. In terms of programming, they are methods that gets executed when a certain join point with matching pointcut is reached in the application.
You can think of Advices as Struts2 interceptors or Servlet Filters. Pointcut: Pointcut are expressions that is matched with join points to determine whether advice needs to be executed or not. Pointcut uses different kinds of expressions that are matched with the join points and Spring framework uses the AspectJ pointcut expression language.
Target Object: They are the object on which advices are applied. Spring AOP is implemented using runtime proxies so this object is always a proxied object. What is means is that a subclass is created at runtime where the target method is overridden and advices are included based on their configuration.
Weaving: It is the process of linking aspects with other objects to create the advised proxy objects. This can be done at compile time, load time or at runtime. Spring AOP performs weaving at the runtime. Before Advice: These advices runs before the execution of join point methods. We can use Before annotation to mark an advice type as Before advice.
After finally Advice: An advice that gets executed after the join point method finishes executing, whether normally or by throwing an exception. We can create after advice using After annotation. After Returning Advice: Sometimes we want advice methods to execute only if the join point method executes normally. We can use AfterReturning annotation to mark a method as after returning advice. After Throwing Advice: This advice gets executed only when join point method throws exception, we can use it to rollback the transaction declaratively.
We use AfterThrowing annotation for this type of advice. Around Advice: This is the most important and powerful advice. This advice surrounds the join point method and we can also choose whether to execute the join point method or not.
We can write advice code that gets executed before and after the execution of the join point method. It is the responsibility of around advice to invoke the join point method and return values if the method is returning something. We use Around annotation to create around advice methods. The points mentioned above may sound confusing but when we will look at the implementation of Spring AOP, things will be more clear. Spring provides support for using AspectJ annotations to create aspects and we will be using that for simplicity.
All the above AOP annotations are defined in org. Spring Tool Suite provides useful information about the aspects, so I would suggest you to use it. Create a new Simple Spring Maven project so that all the Spring Core libraries are included in the pom. Our final project will look like below image, we will look into the Spring core components and Aspect implementations in detail. Also I have updated the Spring framework version to be the latest one as of date i. It is a custom java annotation defined by us in the project.
We will look into its usage later on. EmployeeService class is very standard and just provides us an access point for Employee beans. My project bean configuration file looks like below. Add aop:aspectj-autoproxy element to enable Spring AspectJ support with auto proxy at runtime 3. Aspect; import org. This is a very important point to remember, if we will create Employee bean using new operator the advices will not be applied.
Only when we will use ApplicationContext to get the bean, advices will be applied. We will look these advices in action in a test class after we have looked into all the different types of advices. Pointcut Methods and Reuse Sometimes we have to use same Pointcut expression at multiple places, we can create an empty method with Pointcut annotation and then use it as expression in advices.
JoinPoint and Advice Arguments We can use JoinPoint as parameter in the advice methods and using it get the method signature or the target object. We can use args expression in the pointcut to be applied to any method that matches the argument pattern.
If we use this, then we need to use the same name in the advice method from where argument type is determined. We can use Generic objects also in the advice arguments. JoinPoint; import org. AfterReturning; import org. AfterThrowing; import org. We can use AfterReturning advice to get the object returned by the advised method. We have throwException method in the Employee bean to showcase the use of After Throwing advice. Spring Around Aspect Example As explained earlier, we can use Around aspect to cut the method execution before and after.
We can use it to control whether the advised method will execute or not. We can also inspect the returned value and change it. This is the most powerful advice and needs to be applied properly. ProceedingJoinPoint; import org.
Around; import org. For void methods, advice method can return null. Since around advice cut around the advised method, we can control the input and output of the method as well as its execution behavior. For example, someone can define a new spring bean with getName method and the advices will start getting applied to that even though it was not intended. An alternative approach is to create a custom annotation and annotate the methods where we want the advice to be applied.
This is the purpose of having Employee setName method annotated with Loggable annotation. Spring Framework Transactional annotation is a great example of this approach for Spring Transaction Management. This is a very safe approach and whenever we want to apply the advice on any method, all we need is to annotate it with Loggable annotation.
Mar 20, PM org.
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