JAVA Spring's understanding

Spring
1) Open source framework
2) IoC (control inversion), writes the creation and dependency of the class in the configuration file, is injected by the configuration file, realizes the loose coupling
3) AOP will be safe, the transaction is equal to the program logic of the relatively independent function extracted, using the spring configuration file to plug in these functions, implemented in accordance with the aspect of programming, improve the reusability of

Or a concept spring is a lightweight container (Light-weight container), the core of which is the Bean factory (Bean Factory), which constructs the M (Model) we need.

Based on this, spring provides the implementation of AOP (aspect-oriented programming, level-oriented programming) to provide services such as transactional, security, and so on, in a non-managed environment.

The expansion of the Bean factory applicationcontext more convenient for us to implement the application of the Java EE, the implementation of Dao/orm is convenient for us to develop the database;

Web MVC and the Spring Web provide a framework for Java Web applications or integrate with other popular web frameworks.

In addition, you say the duplicate commits, that is the browser problem, and structs irrelevant. See how you command the browser, if you use redirect, there is no repetition of the problem, because the browser has been redirected. But you use forward, that is, when you refresh the time is to repeat the submission.
Spring is more emphasis on the business layer, on the page is generally not displayed. Of course, if you use spring's MVC exception.

JAVA Spring's understanding