久仰已久的spring居然在职业生涯15年后才开始接触，之前都是公司自己的框架结构。是时候学习新的东西了。
新的知识需要慢慢啃，先来点开胃汤，overview一下Spring组成和大体架构。
以下为自学内容，如有不对，再修正。
Spring Overview
从功能上来分，Spring 官网将其分为三部分, 各有侧重：
Spring Boot：侧重build anything. (Spring Boot is designed to get you up and running as quickly as possible, with minimal upfront configuration of Spring. Spring Boot takes an opinionated view of building production ready applications.) Manual: https://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/
Spring Cloud: 侧重corrdinate anything. (Built directly on Spring Boot's innovative approach to enterprise Java, Spring Cloud simplifies distributed, microservice-style architecture by implementing proven patterns to bring resilience, reliability, and coordination to your microservices.) Manual: http://cloud.spring.io/spring-cloud-static/Finchley.RELEASE/multi/multi_spring-cloud.html
Spring Cloud Data Flow:侧重 Connect anything. (Connect the Enterprise to the Internet of Anything-mobile devices, sensors, wearables, automobiles, and more. Spring Cloud Data Flow provides a unified service for creating composable data microservices that address streaming and ETL-based data processing patterns.) Manual: http://cloud.spring.io/spring-cloud-static/Finchley.RELEASE/
Spring Framework 5
