白菜Java自习室 涵盖核心知识
Spring Cloud 版本重大变革，变更了版本号的命名方式。
从 Spring Cloud 2020.0.0-M1 开始，Spring Cloud 废除了这种英国伦敦地铁站的命名方式，而使用了全新的 "日历化" 版本命名方式。
下面是截取自官宣的一段内容：
Notable Changes in the 2020 Release Train
We have changed our release train versioning scheme. We now follow Calendar Versioning or calver for short. We > > will follow the YYYY.MINOR.MICRO scheme where MINOR is an incrementing number that starts at zero each year. The MICRO segment corresponds to suffixes previously used: .0 is analogous to .RELEASE and .2 is analogous to .SR2. Pre-release suffixes will also change from using a . to a - for the separator, for example 2020.0.0-M1 and 2020.0.0-RC2. We will also stop prefixing snapshots with BUILD- – for example 2020.0.0-SNAPSHOT.
We will continue to use London Tube Station names for code names. The current codename is Ilford. These names will no longer be used in versions published to maven repositories.
Spring Cloud AWS and Spring Cloud GCP are no longer part of the release train. They will continue to be part of Hoxton as long as it is supported – at least thru June of 2021. Spring Cloud GCP will continue on as a separate project in github.com/GoogleCloud….
Initial milestones are based on Spring Boot 2.3.x but will shift to 2.4.x once that line has started.
The 2020.0 Release Train will be available on start.spring.io once development has started on the next feature release of Spring Boot (2.4.0). Please see Getting Started, below, for instructions on including this release in your project.
In all, a total of 183 issues, enhancements, bugs and pull requests were included in this release. See the GitHub project for details.
什么是日历化版本？
英文名称：Calendar Versioning
日历化版本不是基于任意的数字，而是基于项目的发布日期的版本控制约定，随着时间的推移，版本会越来越好。
这种基于日期的版本命名方式被称为 “日历化版本”（Calendar Versioning）， 或者可以简称 CalVer。
详细的介绍参考：
Versioning gets better with time.
For maintainers, versioning allows us to specify precise dependencies within an ever-expanding ecosystem. For sellers and promoters, a project's version is a dynamic part of a brand. For all of us, versioning lets us reference the past while upgrading to the future.
Different projects use different systems for versioning, but common practices have emerged. For instance, point-separated numbers (e.g., 3.1.4) are all but given. Another common versioning pattern incorporates a time-based element, usually part of the release date.
This date-based approach has come to be called Calendar Versioning, or CalVer for short.
我们来看下 Spring Cloud 是如何开始使用日历化版本的。
Spring Cloud 使用了 YYYY.MINOR.MICRO 的命名规则：
- YYYY：表示 4 位年份；
- MINOR：代表一个递增的数字，每年以 0 开始递增；
- MICRO：代表版本号后缀，就和之前使用的 .0 类似于 .RELEASE 一样，.2 类似于 .SR2。 预发布版本的后缀分隔符也从 . 变更为 -，如：2020.0.0-M1 和 2020.0.0-RC2 命名所示。
同时，Spring Cloud 将停止给快照版本添加 BUILD- 前缀，如：2020.0.0-SNAPSHOT 命名所示。
但是，英国伦敦地铁站的命名没有彻底废除，Spring Cloud 将继续使用它作为版本代号，当前代号：Ilford，只是发布到 Maven 仓库的版本将不再使用这些名称。
最后就再来欣赏下 Maven 下的 Spring Cloud 新老版本号命名方式：
老版本命名：
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Hoxton.SR6</version>
<type>pom</type>
<scope>runtime</scope>
</dependency>
新版本命名：
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>2020.0.0-M2</version>
<type>pom</type>
<scope>runtime</scope>
</dependency>
使用日历化版本命名方式，我个人觉得会更方便，可以更清楚的看出当前版本的年份，看到字母、纯数字方式的版本号都不知道自己多久没升级了。
