Java Spring multiple ApplicationContext

Question

The definition of the spring ApplicationContext is very ambiguous, I almost finish a whole book of tutorial but still cannot understand what is the Applic

Answer 1

By container they refer to the core spring Inversion of Control container. The container provides a way to initialize/bootstrap your application (loading the configuration in xml files or annotations), through use of reflection, and to manage the lifecycle of Java objects, which are called beans or managed objects.

During this initial phase, you do not have (normally, yet it is possible) control in your application, instead you will get a completely initialized state for the application when the bootstrapping is done (or nothing, in case it fails).

It is a replacement, or possibly an addition, to what is called an EJB3 container; yet, the spring provided one fails to adhere to the EJB defined standard. Historically, adoption of EJB has been limited by the complexity of that specification, with spring being a newly created project for having EJB3 comparable features running on a J2SE jvm and without an EJB container, and with much easier configuration.

ApplicationContext (as an interface, and by the direct implementation flavours) is the mean of implementing this IoC container, as opposed to the BeanFactory, which is now (a sparsely used and) more direct way of managing beans, which by the way provides the base implementation features for the ApplicationContext.

As per your second question, you can have multiple instances of ApplicationContexts, in that case, they will be completely isolated, each with its own configuration.