Spring IoC container

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.

IoC也叫依赖注入。   它是一个通过对象，定义依赖的程序（那些他一起工作的对象）。只有通过构造器参数，工厂方法的参数，或者是已经创建或者由工厂方法返回的堆对象上设置的属性。

The org.springframework.beans and org.springframework.context packages are the basis for Spring Framework’s IoC container.

org.springframework.beans和org.springframework.context是Spring框架IoC的基础包。

The BeanFactory interface provides an advanced configuration mechanism capable of managing any type of object.ApplicationContext is a sub-interface of BeanFactory. It adds easier integration with Spring’s AOP features; message resource handling (for use in internationalization), event publication; and application-layer specific contexts such as the WebApplicationContext for use in web applications.

BeanFactory接口

The idea that a bean definition is a recipe is important, because it means that, as with a class, you can create many object instances from a single recipe.

The scope of the Spring singleton is best described as per container and per bean. This means that if you define one bean for a particular class in a single Spring container, then the Spring container creates one and only one instance of the class defined by that bean definition. The singleton scope is the default scope in Spring.