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Through following method we get servetContext instance in servet. We call following method in init(ServetConfig cfg) { ServertContexr = cfg.getServletContext(); }
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∙ 15y ago
You can get the ServletContext instance in a servlet by using the getServletContext() method provided by the HttpServlet class, which is the base class for servlets. This method returns the ServletContext object associated with the servlet. For example: ServletContext context = getServletContext();
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What is the difference between servlet context page context?
ServletContext is an interface for communication with the servlet container while PageContext is an object for managing data related to a JSP page. ServletContext is used for application-wide resources while PageContext is specific to a single JSP page.
What is servlet context?
The ServletContext is an object provided by the servlet container that allows servlets to communicate with the container. It represents the configuration and environment of a web application and provides access to resources such as parameters, attributes, and initialization parameters. Servlets can use the ServletContext to perform tasks like accessing resources, logging events, and managing session persistence.
How do you get the image file from the database with JSP?
You can retrieve an image file from a database in JSP by writing a servlet that fetches the image from the database and streams it to the JSP page. The servlet will set the content type to "image/jpeg" or the appropriate image format and write the image data to the response output stream. In the JSP page, you can then display the image by setting the source attribute of the img tag to the servlet URL.
How do you dynamically identify the jsp in servlet?
You can dynamically identify the JSP file in a servlet by using the request URL or request parameters to determine which JSP to forward the request to. You can also store necessary information in session attributes or external configurations to help determine the appropriate JSP to display. Finally, you can use a servlet mapping or URL pattern to route requests to different JSP files based on the URL.
What is Servlet API used for connecting database?
The Servlet API is not specifically used for connecting to databases. Instead, servlets typically interact with databases through JDBC (Java Database Connectivity), which is a standard Java API for database access. Servlets can use JDBC to establish connections, execute SQL queries, and retrieve results from a database.
How do you get ServletContext object in EJB - 38k?
get servlet context path from EJB
What is servlet?
server side program or single instance multiple threads.
Is Servlet instance Thread safe If not how can you make thread safe?
No. The Servlet is not thread-safe by default. You can make it thread safe by implementing the SingleThreadedModel interface
What is difference between single threaded servlet and multi threaded servlet?
The single thread model means that your servlet would not be multi-threaded. If there are two concurrent requests to your servlet then 2 instances of your servlet will be created to process these 2 requests. You can implement the single thread model by implementing the SingleThreadModel interface in your class. This is just a marker interface and does not have any methods. The multi threaded model means that your servlet would be multi-threaded and only one instance would exist. Multiple concurrent requests would be served by the same instance but in different threads. You can implement the multi threaded model by not implementing the SingleThreadModel interface in your servlet class.
What is session in jsp?
Session in the JSP and Servlet context refers to an instance of the HttpSession object that contains all the information about the current user session with the web application. This can be used as a cache or temporary storage area to store values that might be required across the application.
Which method is used to retrive an initialitation parameters from a servlet context?
ServletContext sc=getServletContext(); String s=sc.getInitParameter();
How do JSP methods get translated to Servlet methods?
A JSP gets converted into a Servlet for execution and hence the methods in a JSP are similar to the ones in a Servlet.Scriptlets and Expressions will end up in the body of doGet or doPostDeclarations will end up as instance variablesjspInit() and jspDestroy() will get translated to Servlet's init() and destroy() methods
What is javax servlet?
A Servlet is a Java programming language class used to extend the capabilities of a server. Although servlets can respond to any types of requests, they are commonly used to extend the applications hosted by web serversA Servlet is a Java-based server-side web technology.The javax.servlet package contains a number of classes and interfaces that describe and define the contracts between a servlet class and the runtime environment provided for an instance of such a class by a conforming servlet container.
What are types of servlet?
Http servlet and Generic servlet
What is java servlet chaining?
Servlet Chaining means the output of one servlet act as a input to another servlet. Servlet Aliasing allows us to invoke more than one servlet in sequence when the URL is opened with a common servlet alias. The output from first Servlet is sent as input to other Servlet and so on. The Output from the last Servlet is sent back to the browser. The entire process is called Servlet Chaining.
How does Apache httpd work?
Tomcat is a servlet container, and the following is how a servlet container works The init, service, and destroy methods are the servlet's lifecycle methods. The init method is called once by the servlet container after the servlet class has been instantiated to indicate to the servlet that it being placed into service. The init method must complete successfully before the servlet can receive any requests. A servlet programmer can override this method to write initialization code that needs to run only once, such as loading a database driver, initializing values, and so on. In other cases, this method is normally left blank. The service method is then called by the servlet container to allow the servlet to respond to a request. The servlet container passes a javax.servlet.ServletRequest object and a javax.servlet.ServletResponse object. The ServletRequest object contains the client's HTTP request information and the ServletResponse encapsulates the servlet's response. These two objects enable you to write custom code that determines how the servlet services the client request. The servlet container calls the destroy method before removing a servlet instance from service. This normally happens when the servlet container is shut down or when the servlet container needs some free memory. This method is called only after all threads within the servlet's service method have exited or after a timeout period has passed. After the servlet container calls destroy, it will not call the service method again on this servlet. The destroy method gives the servlet an opportunity to clean up any resources that are being held (for example, memory, file handles, and threads) and make sure that any persistent state is synchronized with the servlet's current state in memory. For Better Picture, Visit below article full of images to clear the concept : http://shivasoft.in/blog/java/servlet/how-container-handles-the-servlet-request/
How many interfaces in a java servlet package?
The javax.servlet package defines 12 interfaces, 7 classes, and 2 exceptions. The Interfaces are as follows:• Filter:- Preprocessor of the request before it reaches a servlet. It can also be a postprocessor of the response leaving a servlet. It can modify a request or response (for example, change headers), the request to a resource (a servlet or static content), or the response from a resource.• RequestDispatcher:- This is the servlet version of a redirect. It enables requests to be processed and then forwarded to other components of a Web application, such as another servlet, HTML file, or JSP file.• Servlet:- Defines the life-cycle methods that are implemented by all servlets.• ServletConfig:- This class has the methods for accessing the servlet configuration information such as the servlets name (from the web.xml file), the initialization parameters, and the ServletContext object.• ServletContext:- These methods enable your servlet to communicate with its servlet container. This is how you get the MIME type of a file, dispatch requests, or write to a log file. Notice that this information has application scope. The most important features of the ServletContext are application-scope attributes access, logging, and context initialization parameters.• ServletContextAttributeListener:- Implementations of this interface receive notifications of changes to the attribute list on the servlet context of a Web application. Supports the handling of the ServletContextAttributeEvent class.• ServletContextListener:- An interface that supports the handling of the ServletContextEvent class. Defines a set of methods that a servlet uses to communicate with its servlet container. It can get the MIME type of a file, dispatch requests, or write to a log file. Notice that there is one context per "Web application" per Java Virtual Machine. The specification defines a "Web application" as a collection of servlets and content installed under a specific subset of the server's URL namespace, such as /catalog, and possibly installed via a .war file.• ServletRequest:- This interface forms the base for the class that provides client request information to a servlet. It is protocol-independent.• ServletResponse:- This interface forms the base for the class that represents the response sent from the servlet to the client.• SingleThreadModel:- An interface that ensures a given servlet handles only one request at a time.
