@postconstruct and @preconstruct annotations for Java development

Starting with the Java EE5 specification, the servlet adds two annotations (Annotation) that affect the servlet life cycle: @PostConstruct and @preconstruct. These two annotations are used to decorate a non-static void () method. And this method cannot have a throw exception declaration.

How to use, for example:

Way 1@postconstruct public void SomeMethod () {    ...} Way 2public @PostConstruct void SomeMethod () {    ...}

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The method that is modified by @postconstruct will run when the server loads the servlet and will only be called once by the server, similar to the Serclet Inti () method. Methods that are modified by @postconstruct will run before the Init () method after the constructor.

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The @preconstruct-modified method runs when the server unloads the servlet and is only called once by the server, similar to the Destroy () method of the servlet. Methods that are modified by @preconstruct are run after the Destroy () method, before the servlet is completely uninstalled.

@postconstruct and @preconstruct annotations for Java development