Java web Listener Listener

Listener: Listener

Concept: One of the three major components of web

• Event listener mechanism

  • Event: One thing
  • Event Source: Local events
  • Listener: An object
  • Register listeners: event, event source, listeners are bound together. When an event occurs on the event source, listeners execute code.

• ServletContextListener: create and destroy objects listening Servletconte

  • void contextDestroy (ServletContextEvent sce): calls before being destroyed
  • void contextInitialized (ServletContextEvent sce): After the object is created will be called

• step

  • Defining class implements interfaces ServletContextListener

  • Replication method

  • Configuration

    • web.xml

      • <listener></listener>
        

    • annotation

      • @WebListener