What design patterns are used in Spring framework

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Service Locator Pattern - ServiceLocatorFactoryBean keeps information of all the beans in the context  When client code asks for a service  bean  using name  it simply locates that bean in the context and returns it  Client code does not need to write spring related code to locate a bean

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Factory pattern is also used for loading beans through BeanFactory and Application context

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Factory Method patter  BeanFactory for creating instance of an object Singleton   instance type can be singleton for a context Prototype   instance type can be prototype  Builder pattern  you can also define a method in a class who will be responsible for creating complex instance

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There are loads of different design patterns used  but there are a few obvious ones    Proxy - used heavily in AOP  and remoting  Singleton - beans defined in spring config files are singletons by default  Template method - used extensively to deal with boilerplate repeated code  such as closing connections cleanly  etc     For example JdbcTemplate  JmsTemplate  JpaTemplate      Update following comments  For MVC  you might want to read the MVC Reference  Some obvious patterns in use in MVC    Model View Controller  -      The advantage with Spring MVC is that your controllers are POJOs as opposed to being servlets  This makes for easier testing of controllers  One thing to note is that the controller is only required to return a logical view name  and the view selection is left to a separate ViewResolver  This makes it easier to reuse controllers for different view technologies  Front Controller  Spring provides DispatcherServlet to ensure an incoming request gets dispatched to your controllers  View Helper - Spring has a number of custom JSP tags  and velocity macros  to assist in separating code from presentation in views

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Spring container generates bean objects depending on the bean scope  singleton  prototype etc     So this looks like implementing Abstract Factory pattern  In the Spring s internal implementation  I am sure each scope should be tied to specific factory kind class

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The DI thing actually is some kind of strategy pattern  Whenever you want to be some logic implementation exchangeable you typically find an interface and an appropriate setter method on the host class to wire your custom implementation of that interface

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Spring is a collection of best-practise API patterns  you can write up a shopping list of them as long as your arm  The way that the API is designed encourages you  but doesn t force you  to follow these patterns  and half the time you follow them without knowing you are doing so

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And of course dependency injection  or IoC  inversion of control   which is central to the whole BeanFactory ApplicationContext stuff

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Observer-Observable  it is used in ApplicationContext s event mechanism

[design-patterns] What design patterns are used in Spring framework?

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