What is a servlet context listener?
What is a servlet context listener?
ServletContextListener is an interface that gets notified about ServletContext lifecycle changes. It offers two methods. contextInitialized – Is triggered when the web application is starting the initialization. This will be invoked before any of the filters and servlets are initialized.
What is servlet context in JSP?
The ServletContext is accessible via the application implicit object. Since each JSP is a servlet, you can also use getServletContext() . But.. avoid having code like that in the JSP. Instead, obtain the value you need in your servlet and set it as a request attribute, simply reading it in the JSP (via JSTL preferably)
How do you deploy a servlet context listener within a web application?
In this example, we will show you how to create a custom listener class by implementing ServletContextListener , which run your code before the web application is started. 1.1 Create a class and implement the ServletContextListener interface. 1.2 Put it in the deployment descriptor. 1.3 Starting Tomcat….
What are the methods available in servlet context listener interface?
There are two methods declared in the ServletContextListener interface which must be implemented by the servlet programmer to perform some action such as creating database connection etc. public void contextInitialized(ServletContextEvent e): is invoked when application is deployed on the server.
How can one JSP communicate with Java file?
Wherein an object will be communicated to a JSP from a Servlet….Following are the steps in Servlet JSP Communication:
- Servlet instantiates a bean and initializes it.
- The bean is then placed into the request.
- The call is then forwarded to the JSP page, using request dispatcher.
What is the purpose of events and listeners in servlets?
Application events provide notifications of a change in state of the servlet context (each Web application uses its own servlet context) or of an HTTP session object. You write event listener classes that respond to these changes in state, and you configure and deploy them in a Web application.
What is servlet context and config?
The ServletConfig parameters are specified for a particular servlet and are unknown to other servlets. It is used for intializing purposes. The ServletContext parameters are specified for an entire application outside of any particular servlet and are available to all the servlets within that application.
Which JSP implicit object represents the servlet context object for the web application?
Application object (code line 10) is an instance of javax. servlet. ServletContext and it is used to get the context information and attributes in JSP.
What is a servlet listener used for?
Servlet Listener is used for listening to events in a web container, such as when you create a session or place an attribute in a session or if you passivate and activate in another container, to subscribe to these events you can configure listener in web. xml, for example, HttpSessionListener.
What are the two main types of servlet?
There are two main servlet types, generic and HTTP:
- Generic servlets. Extend javax. servlet. GenericServlet. Are protocol independent.
- HTTP servlets. Extend javax. servlet. HttpServlet. Have built-in HTTP protocol support and are more useful in a Sun Java System Web Server environment.
How is servlet different from CGI?
For such applications, HTTP-specific servlet classes are defined by Java Servlet technology….Difference between Java Servlet and CGI.
| Basis | Servlet | CGI |
|---|---|---|
| Data Sharing | Data sharing is possible. | Data sharing is not possible. |
| Link | It links directly to the server. | It does not links directly to the server. |
Which two types of text is included in JSP page?
A JSP page is a text document that contains two types of text: static data, which can be expressed in any text-based format (such as HTML, SVG, WML, and XML), and JSP elements, which construct dynamic content.
Is servletcontextlistener a servlet or JSP?
Context listener is not a servlet or JSP, it’s a class that implements ServletContextListener interface and provides definition of contextDestroyed() and contextInitialized().
What is context listener in JSP?
Making and Using a context listener. Context listener is not a servlet or JSP, it’s a class that implements ServletContextListener interface and provides definition of contextDestroyed() and contextInitialized().
What is servlet listener in Java?
Listener is one of the most popular technologies used in the J2EE web application. It is part of the Java Servlet as defined in Servlet 2.3 but they have their own specific functionalities. There are two most widely used Servlet Listener i.e. ServletContextListener and HttpSessionListener.
What is session listener listener in Java?
Session Listener Listener is one of the most popular technologies used in the J2EE web application. It is part of the Java Servlet as defined in Servlet 2.3 but they have their own specific functionalities. There are two most widely used Servlet Listener i.e. ServletContextListener and HttpSessionListener.
