什么是Spring IoC 容器？
答：Spring Framework implementation of the Inversion of
Control (IoC) principle. IoC is also known as dependency
injection (DI). It is a process whereby objects define their
dependencies (that is, the other objects they work with) only
through constructor arguments, arguments to a factory
method, or properties that are set on the object instance after it
is constructed or returned from a factory method. The container
then injects those dependencies when it creates the bean.
控制反转（IoC）原理的Spring框架实现。IoC也称为依赖注入（dependency injection，DI）。这是一个过程，在这个过程中，对象只通过构造函数参数、工厂方法的参数或在对象实例构造或从工厂方法返回后在对象实例上设置的属性来定义它们的依赖项（即它们使用的其他对象）。然后容器在创建bean时注入这些依赖项。