1. What is Spring?
①Spring is an open source framework;
②Spring was born to simplify enterprise-level application development. Using Spring enables simple JavaBeans to do things that were previously only possible with EJBs.
③ Spring is an IOC (DI) and AOP container framework.
2. Describe Spring in detail:
①Lightweight: Spring is non-intrusive - objects in applications developed based on Spring can not depend on Spring's API;
②Dependency injection: (DI --- dependency injection, IOC);
③Aspect-oriented programming: (AOP --- aspect oriented programming);
④Container: Spring is a container because it contains and manages the life cycle of application objects;
⑤Framework: Spring realizes the combination of simple component configuration into a complex application. In Spring, XML and Java annotations can be used to combine these objects;
⑥One-stop: On the basis of IOC and AOP, it can integrate open source frameworks of various enterprise applications and excellent third-party class libraries (in fact, Spring itself also provides SpringMVC for the presentation layer and Spring JDBC for the persistence layer);