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Spring Framework Overview

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Spring Framework Overview

Spring Framework Overview

Spring makes it easy to create Java enterprise applications. It provides everything you need to embrace the Java language in an enterprise environment, with support for Groovy and Kotlin as alternative languages on the JVM, and with the flexibility to create many kinds of architectures depending on an application’s needs. As of Spring Framework 6.0, Spring requires Java 17+.

Spring supports a wide range of application scenarios. In a large enterprise, applications often exist for a long time and have to run on a JDK and application server whose upgrade cycle is beyond the developer’s control. Others may run as a single jar with the server embedded, possibly in a cloud environment. Yet others may be standalone applications (such as batch or integration workloads) that do not need a server.

Spring is open source. It has a large and active community that provides continuous feedback based on a diverse range of real-world use cases. This has helped Spring to successfully evolve over a very long time.

Spring 让创建 Java 企业级应用变得简单。它提供了在企业环境中使用 Java 语言所需的一切，同时支持将 Groovy 和 Kotlin 作为 JVM 上的替代语言，并能根据应用程序的需求灵活构建多种架构。从 Spring Framework 6.0 开始，Spring 要求使用 Java 17 或更高版本。

Spring 支持广泛的应用场景。在大型企业中，应用程序往往需要长期运行，并且必须在开发者无法控制的升级周期下的 JDK 和应用服务器上运行。另一些应用可能以单一 jar 包的形式运行，内嵌服务器，可能部署在云环境中。还有一些可能是不需要服务器的独立应用程序（如批处理或集成任务）。

Spring 是开源的。它拥有庞大且活跃的社区，该社区基于丰富多样的实际应用场景，持续提供反馈。这也帮助 Spring 在很长一段时间内成功演进。

说明：

  1. make it easy to do something → 让做某事变得简单 / 便于做某事

  2. embrace the Java language in an enterprise environment → 在企业环境中使用 Java 语言

  3. alternative languages on the JVM → JVM 上的替代语言（如 Groovy、Kotlin）

  4. flexibility to create many kinds of architectures → 灵活构建多种架构

  5. requires Java 17+ → 要求使用 Java 17 或更高版本

  6. run as a single jar with the server embedded → 以单一 jar 包形式运行，内嵌服务器

  7. standalone applications → 独立应用程序（不依赖外部服务器，比如批处理或集成任务）

  8. open source → 开源的

  9. continuous feedback based on real-world use cases → 基于真实应用场景的持续反馈

What We Mean by “Spring”

The term “Spring” means different things in different contexts. It can be used to refer to the Spring Framework project itself, which is where it all started. Over time, other Spring projects have been built on top of the Spring Framework. Most often, when people say “Spring”, they mean the entire family of projects. This reference documentation focuses on the foundation: the Spring Framework itself.

The Spring Framework is divided into modules. Applications can choose which modules they need. At the heart are the modules of the core container, including a configuration model and a dependency injection mechanism. Beyond that, the Spring Framework provides foundational support for different application architectures, including messaging, transactional data and persistence, and web. It also includes the Servlet-based Spring MVC web framework and, in parallel, the Spring WebFlux reactive web framework.

A note about modules: Spring Framework’s jars allow for deployment to the module path (Java Module System). For use in module-enabled applications, the Spring Framework jars come with Automatic-Module-Name manifest entries which define stable language-level module names (spring.core, spring.context, etc.) independent from jar artifact names. The jars follow the same naming pattern with - instead of . – for example, spring-core and spring-context. Of course, Spring Framework’s jars also work fine on the classpath.

术语 “Spring” 在不同的语境中具有不同的含义。它可以用来指代 Spring Framework 项目本身，也就是一切的起源。随着时间的推移，其他 Spring 项目也相继构建在 Spring Framework 之上。大多数情况下，当人们说 “Spring” 时，他们指的是整个 Spring 项目家族。而本参考文档聚焦于基础：即 Spring Framework 本身。

Spring Framework 是由多个模块组成的。应用程序可以根据需要选择所需的模块。其核心是 核心容器（core container）模块，其中包括一个配置模型和一个依赖注入机制。除此之外，Spring Framework 还为不同的应用架构提供了基础支持，包括消息传递、事务性数据与持久化、以及 Web 开发。它还包括基于 Servlet 的 Spring MVC Web 框架，以及与之并列的 Spring WebFlux 响应式 Web 框架。

关于模块的说明： Spring Framework 的 JAR 包支持部署到 模块路径（module path，即 Java 模块系统）。为了在启用了模块功能的应用程序中使用，Spring Framework 的 JAR 包带有 Automatic-Module-Name 清单条目（manifest entries），这些条目定义了与 JAR 工件名称无关的、稳定的语言级别模块名称（例如：spring.core、spring.context 等）。这些 JAR 包遵循与模块名相同的命名规则，使用短横线 “-” 而不是点号 “.”，例如：spring-core 和 spring-context。当然，Spring Framework 的 JAR 包在传统的 类路径（classpath） 上也能正常工作。

说明：

  • The term “Spring” means different things in different contexts.

    → 术语“Spring”在不同语境中具有不同含义。

  • the Spring Framework project itself, which is where it all started.

    → Spring Framework 项目本身，也就是一切的起源。

  • other Spring projects have been built on top of the Spring Framework.

    → 其他 Spring 项目构建在 Spring Framework 之上。

  • the entire family of projects

    → 整个 Spring 项目家族 / Spring 生态系统

  • The Spring Framework is divided into modules.

    → Spring Framework 由多个模块组成。

  • core container（核心容器）

    → Spring 的核心模块，包括 IoC 容器、配置模型和依赖注入机制。

  • configuration model and a dependency injection mechanism

    → 配置模型和依赖注入机制

  • foundational support for different application architectures

    → 为不同应用架构提供基础支持

  • messaging, transactional data and persistence, and web

    → 消息传递、事务性数据与持久化、以及 Web 开发

  • Servlet-based Spring MVC web framework

    → 基于 Servlet 的 Spring MVC Web 框架（传统同步 Web 开发）

  • Spring WebFlux reactive web framework

    → Spring WebFlux 响应式 Web 框架（支持响应式编程）

  • module path（模块路径）

    → Java 9 引入的模块系统（JPMS, Java Platform Module System）中的模块路径

  • Automatic-Module-Name

    → JAR 清单文件（MANIFEST.MF）中用于定义模块名称的条目，即使没有完整的 module-info.java，也能让 JAR 以模块方式工作

  • jar artifact names vs. module names

    → JAR 包工件名称（如 spring-core-6.1.0.jar）与语言级模块名称（如 spring.core）是分开的

  • on the classpath

    → 在传统的类路径（非模块化环境）下运行，依然兼容

History of Spring and the Spring Framework

Spring came into being in 2003 as a response to the complexity of the early J2EE specifications. While some consider Java EE and its modern-day successor Jakarta EE to be in competition with Spring, they are in fact complementary. The Spring programming model does not embrace the Jakarta EE platform specification; rather, it integrates with carefully selected individual specifications from the traditional EE umbrella:

The Spring Framework also supports the Dependency Injection (JSR 330) and Common Annotations (JSR 250) specifications, which application developers may choose to use instead of the Spring-specific mechanisms provided by the Spring Framework. Originally, those were based on common javax packages.

As of Spring Framework 6.0, Spring has been upgraded to the Jakarta EE 9 level (for example, Servlet 5.0+, JPA 3.0+), based on the jakarta namespace instead of the traditional javax packages. With EE 9 as the minimum and EE 10 supported already, Spring is prepared to provide out-of-the-box support for the further evolution of the Jakarta EE APIs. Spring Framework 6.0 is fully compatible with Tomcat 10.1, Jetty 11 and Undertow 2.3 as web servers, and also with Hibernate ORM 6.1.

Over time, the role of Java/Jakarta EE in application development has evolved. In the early days of J2EE and Spring, applications were created to be deployed to an application server. Today, with the help of Spring Boot, applications are created in a devops- and cloud-friendly way, with the Servlet container embedded and trivial to change. As of Spring Framework 5, a WebFlux application does not even use the Servlet API directly and can run on servers (such as Netty) that are not Servlet containers.

Spring continues to innovate and to evolve. Beyond the Spring Framework, there are other projects, such as Spring Boot, Spring Security, Spring Data, Spring Cloud, Spring Batch, among others. It’s important to remember that each project has its own source code repository, issue tracker, and release cadence. See spring.io/projects for the complete list of Spring projects.

Design Philosophy

When you learn about a framework, it’s important to know not only what it does but what principles it follows. Here are the guiding principles of the Spring Framework:

  • Provide choice at every level. Spring lets you defer design decisions as late as possible. For example, you can switch persistence providers through configuration without changing your code. The same is true for many other infrastructure concerns and integration with third-party APIs.
  • Accommodate diverse perspectives. Spring embraces flexibility and is not opinionated about how things should be done. It supports a wide range of application needs with different perspectives.
  • Maintain strong backward compatibility. Spring’s evolution has been carefully managed to force few breaking changes between versions. Spring supports a carefully chosen range of JDK versions and third-party libraries to facilitate maintenance of applications and libraries that depend on Spring.
  • Care about API design. The Spring team puts a lot of thought and time into making APIs that are intuitive and that hold up across many versions and many years.
  • Set high standards for code quality. The Spring Framework puts a strong emphasis on meaningful, current, and accurate javadoc. It is one of very few projects that can claim clean code structure with no circular dependencies between packages.

Feedback and Contributions

For how-to questions or diagnosing or debugging issues, we suggest using Stack Overflow. Click here for a list of the suggested tags to use on Stack Overflow. If you’re fairly certain that there is a problem in the Spring Framework or would like to suggest a feature, please use the GitHub Issues.

If you have a solution in mind or a suggested fix, you can submit a pull request on Github. However, please keep in mind that, for all but the most trivial issues, we expect a ticket to be filed in the issue tracker, where discussions take place and leave a record for future reference.

For more details see the guidelines at the CONTRIBUTING, top-level project page.

Getting Started

If you are just getting started with Spring, you may want to begin using the Spring Framework by creating a Spring Boot-based application. Spring Boot provides a quick (and opinionated) way to create a production-ready Spring-based application. It is based on the Spring Framework, favors convention over configuration, and is designed to get you up and running as quickly as possible.

You can use start.spring.io to generate a basic project or follow one of the “Getting Started” guides, such as Getting Started Building a RESTful Web Service. As well as being easier to digest, these guides are very task focused, and most of them are based on Spring Boot. They also cover other projects from the Spring portfolio that you might want to consider when solving a particular problem.

This post is licensed under CC BY 4.0 by the author.