Configuring Methods Using Annotations in Web Applications 

Use

You can define the moment when a method is called by using the corresponding annotations.

There are two annotations for configuring method invocation:

●      @PostConstruct

This annotation specifies that the method will be called before all lifecycle methods are called.

●      @PreDestroy

This annotation specifies that the method will be called before the servlet object is destroyed.

Procedure

Using the @PostConstruct Annotation

Use this annotation at method level without any attributes.

public class PostConstructAnnot_servlet extends HttpServlet {   //…      @PostConstruct    public void postConstruct() {       //Invocation of init methods, preparative operations       System.out.println("PostConstructAnnot_servlet: "             + " postConstruct method invoked! ");    }   //…   }

Using the @PreDestroy Annotation

Use this annotation at method level without any attributes.

public class PreDestroyAnnot_servlet extends HttpServlet {   //…   @PreDestroy     public void preDestroy(){          //Clean up any open resources            System.out.println("PreDestroyAnnot_servlet: " +                       " preDestoy method invoked! ");     }   //…