What is difference between ServletConfig and ServletContext?
But, the difference lies in the fact that information shared by ServletConfig is for a specific servlet, while information shared by ServletContext is available for all servlets in the web application.
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.
When ServletContextListener is called?
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.
Why do we have servlet listeners?
Why do we have Servlet Listener? We know that using ServletContext , we can create an attribute with application scope that all other servlets can access but we can initialize ServletContext init parameters as String only in deployment descriptor (web. xml). xml to process something when a particular event occurs.
What is diff between JSP and servlet?
Difference between Servlet and JSP
| Servlet | JSP |
|---|---|
| Servlets are faster as compared to JSP, as they have a short response time. | JSP is slower than Servlets, as the first step in the JSP lifecycle is the conversion of JSP to Java code and then the compilation of the code. |
| Servlets are Java-based codes. | JSP are HTML-based codes. |
What is JSP life cycle?
A JSP life cycle is defined as the process from its creation till the destruction. This is similar to a servlet life cycle with an additional step which is required to compile a JSP into servlet.
What is event and listener?
An event listener is a procedure or function in a computer program that waits for an event to occur. Examples of an event are the user clicking or moving the mouse, pressing a key on the keyboard, disk I/O, network activity, or an internal timer or interrupt.
What is event in servlet?
Events are basically occurrence of something. Changing the state of an object is known as an event. There are many Event classes and Listener interfaces in the javax. servlet and javax. servlet.
What is the event associated with HttpSessionAttributeListener?
Interface HttpSessionAttributeListener. Interface for receiving notification events about HttpSession attribute changes. Receives notification that an attribute has been replaced in a session.
What is servlet life cycle?
A servlet life cycle can be defined as the entire process from its creation till the destruction. The servlet is initialized by calling the init() method. The servlet calls service() method to process a client’s request. The servlet is terminated by calling the destroy() method.
What are the tags in JSP?
A tag file is a source file that contains a fragment of JSP code that is reusable as a custom tag. Tag files allow you to create custom tags using JSP syntax. Just as a JSP page gets translated into a servlet class and then compiled, a tag file gets translated into a tag handler and then compiled.
Is JSP front end or backend?
JSP is built on top of the Java Servlet specification. While it is not uncommon to see JSP used as the frontend for older JSF applications, Facelets is the preferred view technology for modern JSF implementations. While JSP may not be your first choice for building dynamic web pages, it is a core Java web technology.
What is the purpose of listeners in servlet?
In this context, to concentrate the events generated by the container and to handle those events Servlet API has provided a group of interfaces called Servlet Listeners. Therefore, the most purpose of Servlet Listeners is to read all the life cycle stages of the request object, the servlet Context object, and HttpSession objects.
What are some good questions for a servlet interview?
Servlet interview questions 1) How many objects of a servlet is created? Only one object at the time of first request by servlet or web container. 2) What is the life-cycle of a servlet? Servlet is loaded servlet is instantiated servlet is initialized service the… 3) What are the life-cycle
What is the role of listener in a GUI application?
The main role of Listener in GUI applications is to concentrate an occasion from the respective GUI component, handle it by executing Listener methods, and remit the response to GUI application. The above process in GUI applications is treated as Event Handling or Event Delegation Model.
When to use httpsessionlistener in servletrequest?
HttpSessionListener is a simple implementation to log the event when the session is created or destroyed. ServletRequestListener is to log the servletRequest IP address when the request is initialized and destroyed.