HttpServlet class

HttpServlet is an abstract class present in javax.servlet.http package. This class is a subclass of GenericServlet class and used widely to create a servlet. Although HttpServlet extends GenericServlet, still there are much differences between them. Differences...

GenericServlet Class

Java provides an alternative way to create a servlet in the form of GenericServlet. It is an abstract class present in javax.servlet package that implements Servlet, ServletConfig and Serializable interface. So, now our servlet program needs to extend GenericServlet....

Servlet AsyncEvent and AsyncListener

AsyncEvent AsyncEvent is an asynchronous event class responsible to generate events. This class is present in javax.servlet package. This event occurs when various asynchronous tasks operating on ServletRequest get completed, expired or generate errors. ServletRequest...

Asynchronous Servlet

In servlets, each request is handled by a thread. Thus the large amount of threads are required for heavy applications. Sometimes a situation arises when a thread waits for a resource or wait for an event. In this case thread may become blocked and degrades the...

Servlet Hidden Form Field

Hidden form field is an invisible field that saves the information regarding the state in client browser. As this information is invisible so client can’t see it but it is visible to servlet. These fields are added to HTML form and when client submit form then these...

Servlet URL Rewriting

This is another approach to maintain the session of a user. In this mechanism, when a client make a request then some extra information is appended in the URL of that request. This extra information uniquely identifies a user and it may be a path info, parameter...

Servlet Cookie

Cookie is a class that is used for session management. It contains a small amount of information which persists between the server and client.  This information includes name, value and other attributes. Servlet send this information to web browser and browser saved...

Servlet HttpSession

HttpSession is an interface used by servlet container to create a session between Http client and Http server. So using this interface we can maintain the state of a user. The object of HttpSession stores various information about the user. This interface is present...

Servlet Session Management

What is session? A session is a link between a client and the server. This link represents some identity that makes client unique so that it is known by the server whenever a request is made. Need to maintain this session? Whenever a client made a request, the server...

Servlet Filter

A filter is an object that is used to obstruct the request and response from server. It has a capability to change the response through Servlet or JSP page. Thus by using filter we can create reusable components. Filter performs various filtering tasks such as...

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