第4页 Chapter 1 Springing in action

It all started with a bean.

1.1 Simplifying Java development
  Lightweight and minimally invasive development with plain old Java objects (POJOs).
  Loose-coupling through dependency injection and interface-orientation.
Spring不用实现不必要的代码，不用继承特定的类，只关注于与你自己的业务逻辑相关的代码开发即可。Spring用Dependency injection来实现这些。
 
  Declarative programming through aspects and common conventions.
通过AOP机制来实现。
  Boilerplate reduction through aspects and templates.
Spring提供了包括JdbcTemplate之类的模板来解决重复写代码的问题。