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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 between GenericServlet and HttpServlet …
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. Although …
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 is initiated by calling startAsync() …
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 …
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 …
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 …
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 …
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. …
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 …
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 …
RequestDispacther is an interface used to receive requests from the users and bind it with other files such as HTML file, Servlet file, JSP file etc. Servlet container is responsible to create RequestDispatcher object. RequestDispacther provides forward() and include() methods. …
ServletContext interface is used to provide the configuration information per web application explicitly. Thus unlike ServletConfig, ServletContext interface can be used to provide information to more than one servlet of web application from web.xml file. So if we want to …
Servlet container uses the object of ServletConfig interface to provide the information to servlet during initialization. ServletConfig object fetch this information from web.xml file. So if we have to provide some dynamic information to servlet then we can pass it …
Servlet handles various client requests and provides their responses. It provides two interfaces i.e ServletRequest and ServletResponse for this purpose. Let’s discuss about these interfaces in detail. ServletRequest interface ServletRequest is an interface whose object is used to provide the …
Annotations are used to provide the information about the program. In servlets if we don’t want to deploy servlet class configurations in web.xml file then we can use annotations. We can say that annotation removes the requirement of web.xml file. …
Java provides a servlet interface in javax.servlet package that is implemented by servlet program either directly or indirectly. This interface provides five methods and these methods must be declared within the servlet program if we are implementing a servlet interface. …
Creating a servlet class is not enough. We have to deploy that class also. So, to deploy the class we use web.xml file. In this file we have to map our class configurations.
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<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>Filename</display-name> <servlet> <servlet-name>ServletName</servlet-name> <servlet-class>ClassName</servlet-class> <servlet> <servlet-mapping> <servlet-name>ServletName</servlet-name> <url-pattern>/PathName</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> </web-app> |
We just required to edit and …
There are two packages in Java Servlet that provide various features to servlet. These two packages are javax.servlet and javax.servlet.http. javax.servlet package: This package contains various servlet interfaces and classes which are capable of handling any type of protocol. javax.servlet.http …
Servlet container is responsible to manage the lifecycle of a servlet. Servlet provides three methods as a part of its lifecycle. Let’s study the lifecycle of servlets with the following steps. Loading class: This is an initial stage of servlet …
Introduction Servlet is a server side Java based programming language widely used to create dynamic web applications. Servlet runs inside a servlet container. It is a portable language so, it will not rely only on one type of web servers. …