Spring Framework

Application framework for Java platform

The Spring Framework is an application framework and inversion of control container for the Java platform. The framework's core features can be used by any Java application, but there are extensions for building web applications on top of the Java EE (Enterprise Edition) platform. The framework does not impose any specific programming model The framework has become popular in the Java community as an addition to the Enterprise JavaBeans (EJB) model. The Spring Framework is free and open source software.

Version Date Notes 0.9 2003 1.0 March 24, 2004 First production release. 2.0 2006 3.0 2009 4.0 2013 5.0 2017 6.0 November 22, 2022

The first version was written by Rod Johnson, who released the framework with the publication of his book Expert One on One J2EE Design and Development in October 2002. The framework was first released under the Apache 2.0 license in June 2003. The first production release, 1.0, was released in March 2004. The Spring 1.2.6 framework won a Jolt productivity award and a JAX Innovation Award in 2006. Spring 2.0 was released in October 2006, Spring 2.5 in November 2007, Spring 3.0 in December 2009, Spring 3.1 in December 2011, and Spring 3.2.5 in November 2013. Spring Framework 4.0 was released in December 2013. Notable improvements in Spring 4.0 included support for Java SE (Standard Edition) 8, Groovy 2,
some aspects of Java EE 7, and WebSocket. Spring Framework 4.2.0 was released on 31 July 2015 and was immediately upgraded to version 4.2.1, which was released on 01 Sept 2015. It is "compatible with Java 6, 7 and 8, with a focus on core refinements and modern web capabilities". Spring Framework 4.3 has been released on 10 June 2016 and was supported until 2020. It was announced to "be the final generation within the general Spring 4 system requirements (Java 6+, Servlet 2.5+), [ ]". Spring Framework 6.0 has been released on 16 November 2022 and came with a Java 17+ baseline and a move to Jakarta EE 9+ (in the jakarta namespace), with a focus on the recently released Jakarta EE 10 APIs such as Servlet 6.0 and JPA 3.1.

The inversion of control (IoC) container is the core container in the Spring Framework. It provides a consistent means of configuring and managing Java objects using reflection. The container is responsible for managing object lifecycles of specific objects: creating these objects, calling their initialization methods, and configuring these objects by wiring them together. In many cases, one need not use the container when using other parts of the Spring Framework, although using it will likely make an application easier to configure and customize. The Spring container provides a consistent mechanism to configure applications and integrates with almost all Java environments, from small scale applications to large enterprise applications. The programmer does not directly create an object, but describes how it should be created, by defining it in the Spring configuration file. Similarly, services and components are not called directly; instead a Spring configuration file defines which services and components must be called. This IoC is intended to increase the ease of maintenance and testing.

Objects created by the container are called managed objects or beans. The container can be configured by loading XML (Extensible Markup Language) files or detecting specific Java annotations on configuration classes. These data sources contain the bean definitions that provide the information required to create the beans. The is a Spring specific annotation that marks a class as the configuration class. The configuration class provides the beans to the Spring Each of the methods in the Spring configuration class is configured with the annotation. The interface will then return the objects configured with the annotation as beans. The advantage of java based configuration over XML based configuration is better type safety and refactorability.

There are several types of Inversion of Control. Dependency injection and dependency lookup are examples of Inversion of Control. Objects can be obtained by means of either dependency lookup or dependency injection.

Dependency injection is a pattern where the container passes objects by name to other objects, via either constructors, properties, or factory methods. There are several ways to implement dependency injection: constructor based dependency injection, setter based dependency injection and field based dependency injection.

Dependency lookup is a pattern where a caller asks the container object for an object with a specific name or of a specific type.

The Spring framework has a feature known as autowiring, which uses the spring container to automatically satisfy the dependencies specified in the JavaBean properties to objects of the appropriate type in the current factory. This can only occur if there is only one object with the appropriate type. There are several annotations that can be used for autowiring POJOs, including the Spring specific annotation (as well as several other Spring specific annotations that help resolve autowire ambiguity such as the or annotations), and the standard Java annotations and
The annotation can be used on a class that defines a bean to inform Spring to prioritize the bean creation when autowiring it by name. The annotation can be used on a class that defines a bean to inform Spring to prioritize the bean creation when autowiring it by type. The annotation is an annotation that conforms to JSR 250, or Common Annotations for the Java Platform. The annotation is used for autowiring references to POJOs by name. The annotation is annotation that conforms to JSR 300, or Standard Annotations for injection. The annotation is used for autowiring references to POJOs by type.

When a user clicks a link or submits a form in their web browser, the request goes to the Spring DispatcherServlet. DispatcherServlet is a front controller in Spring MVC. The DispatcherServlet is highly customizable and flexible. Specifically, it is capable of handling more types of handlers than any implementations of org. springframework. web. servlet. mvc. Controller or org. springframework. stereotype. Controller annotated classes. It consults one or more handler mappings. DispatcherServlet chooses an appropriate controller and forwards the request to it. The Controller processes the particular request and generates a result. It is known as Model. This information needs to be formatted in html or any front end technology like Jakarta Server Pages (also known as JSP) or Thymeleaf. This is the View of an application. All of the information is in the Model And View object. When the controller is not coupled to a particular view, DispatcherServlet finds the actual View (such as JSP) with the help of ViewResolver.

An essential rule for dealing with data streams effectively is to never block. The WebSocket is a viable solution to this problem. The WebSocket Protocol is a low level transport protocol that allows full duplex communication channels over a TCP connection. The WebSocket acts as an alternative to HTTP to enable two way communication between the client and the server. The WebSocket is especially useful for applications that require frequent and fast exchanges of small data chunks, at a high speed and volume. Spring supports the WebSocket protocol by providing the WebSocket API for the reactive application. The @EnableWebSocket annotation gives Websocket request processing functionality when places in a Spring configuration class. A mandatory interface is the WebSocketConfigurer which grants access to the WebSocketConfigurer. Then, the Websocket URL is mapped to the relevant handlers by implementing the registerWebSocketHandlers(WebSocketHandlerRegistry) method .

Spring WebFlux is a framework following the functional programming paradigm, designed for building reactive Spring applications. This framework uses functional programming and Reactive Streams extensively. A good use case for Spring WebFlux is for applications that require sending and receiving instantaneous information, such as a web application with chatting capabilities. Although applications using Spring WebFlux technology is usually less readable than their MVC counterparts, they are more resilient, and simpler to extend. Spring WebFlux reduces the need to deal with the complications associated with synchronizing thread access. Spring WebFlux supports server sent events (SSE), which is a server push technology that allows the client to get automatic updates from a server through an HTTP connection. This communication is unidirectional, and shares many similarities with the publish/subscribe model found in JMS.

The container can be turned into a partially compliant EJB (Enterprise JavaBeans) 3.0 container by means of the Pitchfork project. Some criticize the Spring Framework for not complying with standards. However, SpringSource doesn't see EJB 3 compliance as a major goal, and claims that the Spring Framework and the container allow for more powerful programming models.

A remote code execution vulnerability affecting certain versions of Spring Framework was published in April 2022 under It was given the name Spring4Shell in reference to the recent Log4Shell vulnerability, both having similar proofs of concept in which attackers could on vulnerable machines, gain shell access or even full control.