Questions and Answers

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1 Q.1) Servlet mapping defines A. An association between a URL pattern and a servlet B. An association between a URL pattern and a request page C. An association between a URL pattern and a response page D. All of the above ANSWER : An association between a URL pattern and a servlet Servlet mapping specifies the web container of which java servlet should be invoked for a url given by client. It maps url patterns to servlets. When there is a request from a client, servlet container decides to which application it should forward to. Then context path of url is matched for mapping servlets Q.2) What are the mechanisms available in ServletContextListener interface? A. contextinit(), contextservice(), contextdestroyed() B. contextinitialized((),contextdestroyed() C. contextinitialized(), contextservice(), contextdestroyed() ANSWER : contextinitialized((),contextdestroyed() public void contextinitialized(servletcontextevent sce): Notification that the web application is ready to process requests. contextdestroyed: public void contextdestroyed(servletcontextevent sce) Notification that the servlet context is about to be shut down. Q.3) Which of the following methods are main methods in life cycle of servlet? 1.init() 2.service() 3.destroy() 4.srop() 5.wait() A. 1,2,3,4,5 B. 1,2,3 C. 3,4,5 D. 1,4,5 ANSWER : 1,2,3 Init() Init method is called when Servlet first loaded in to the web server memory. Service() Once initialized, Servlets stays in memory to process requests. Servlets read the data provided in the request in the service() method. Destroy() When server unloads servlets, destroy() method is called to clean up resources the servlet is consuming. Q.4) What is the limit of data to be passed from HTML when doget() method is used? A. 4K B. 8K C. 2K D. 1K ANSWER : 2K Page 1

2 Using get method we can able to pass 2K data from HTML All data we are passing to Server will be displayed in URL (request string). Q.5) To get the servlet environment information A. ServletConfig object is used B. ServletException object is used C. ServletContext object is used D. ServletContainer object is used ANSWER : ServletContext object is used A servlet lives and dies within the bounds of the server process. To understand its operating environment, a servlet can get information about its environment at different times. Servlet initialization information is available during servlet start-up; information about the hosting server is available at any time; and each service request can contain specific contextual information. Q.6) The major difference between servlet and CGI is A. Servlets are thread based and CGI is process based B. Servlets executes slower compared to CGI C. Servlet has no platform specific API, where as CGI has D. All of the above ANSWER : Servlets are thread based and CGI is process based The first advantage of servlets over CGI is in its platform independence. Servlets can run on any operating system just as long as a JVM is installed, which means that you would not be having any problem even if you choose to switch operating systems. With CGI, switching operating system is a difficult and laborious process as you would need to recompile the programs in the new operating system. Servlets are thread based and CGI is process based Q.7) A JSP is transformed into a(n): A. Java applet B. Java servlet C. Either 1 or 2 above D. Neither 1 nor 2 above ANSWER : Java servlet Servlets are commonly used to generate dynamic responses to HTTP requests. Q.8) Which of the following is used to redirect the response from a servlet to a JSP page? A. response.sendredirect() B. request.sendredirect() C. request.forward() D. response.forward() ANSWER : response.sendredirect() response.sendredirect() is used to redirect the response from a servlet to a JSP page. Q.9) The tasks authentication-blocking of requests, data compression, logging and auditing are performed by Page 2

3 A. servlet filter B. servlet config C. servlet context D. servletcontainer ANSWER : servlet filter Filters can be used to transform the response from a servlet or a JSP page and can perform many functions as follows: User Authentication- Blocking requests based on user identity. Logging and auditing- Tracking users and the actions performed. Image conversion- Scaling, sqeezing etc Data compression- For making the download easier. Localization- Targeting the request and response to a particular locale. Q.10) The values of <servlet-name> and <servlet-class> in web.xml file A. Must be same B. Must not be same C. Must not be same ANSWER : Must not be same In servlet also servlet class is triggered by servlet name only not by servlet class.because one class will perform amny different actions. Each action should be identify by the name. Q.11) The include() method of RequestDispatcher A. Sends a request to another resource like servlet, jsp or html B. Includes resource of file like servlet, jsp or html C. Appends the request and response objects to the current servlet ANSWER : Includes resource of file like servlet, jsp or html The include() method merges the response written by the calling servlet, and the activated servlet. This way you can achieve "server side includes" using the include(). Q.12) What is Temporary Servlet? A. Servlet that is destroyed at run tim B. Servlet that exists for a session C. Servlet that is started and stopped for each request D. None of these ANSWER : Servlet that is started and stopped for each request A temporary servlet is started when a request arrives and shut down after the response is generated. A permanent servlet is loaded when the server is started and lives until the server is shut down. * This is useful when startup costs are high, such as a servlet that establishes a connection to a database. * Also useful for permanent server-side service, such as an RMI server. * Provides faster response to client requests when this is crucial. Being temporary or permanent is part of the server configuration. Q.13) Which option is true for HttpServletRequest interface to access Path information? Page 3

4 A. getcontextpath() B. getservletpath() C. getpathinfo() D. None of this ANSWER : 1.getContextPath() 2.getServletPath() 3.getPathInfo() getcontextpath():-the default behavior of this method is to return getcontextpath() on the wrapped request object. getservletpath():-the default behavior of this method is to return getservletpath() on the wrapped request object. Q.14) The Java specification defines an application programming interface for communication between the Web server and the application program. A. Servlet B. Server C. Program D. Randomize ANSWER : Servlet Servlets are commonly used to generate dynamic responses to HTTP requests. Q.15) Choose correct ansewrs 1. Servlet is a Java technology based Web component. 2. Servlet servlets are platform-independent 3. Servlet has run on Web server which has a containers 4. Servlets interact with Web clients via a request/response using HTTP protocol. A. 1,2,3,4 B. 1,2,3 C. 1,3,4 D. None ANSWER : 1,2,3,4 Servlets provide a component-based, platform-independent method for building Web-based applications, without the performance limitations of CGI programs. Servlets have access to the entire family of Java APIs, including the JDBC API to access enterprise databases. Q.16) The life cycle of a servlet is managed by A. Servlet context B. Servlet container C. The supporting protocol (such as http or https) D. All of the above ANSWER : Servlet container A servlet is unloaded by the container if the container shuts down, or if the container reloads the whole web application at runtime. Q.17) How many ServletContext objects are available for an entire web application? A. One each per servlet Page 4

5 B. One each per request C. One each per response D. Only one ANSWER : Only one There is one ServletConfig object per servlet. So if there are 10 servlets in an application, there would be 10 ServletConfig objects. And there is only one ServletContext object per aplication. Q.18) The getsession() method with "true" as its parameter [ getsession(true) ] it will return the appropriate session object when A. The session is completed B. The session object is passed to another method C. The session does not exists D. The session is existing ANSWER : The session is existing The getsession(true) will check whether a session already exists for the user. If yes, it will return that session object else it will create a new session object and return it. While getsession(false) will check existence of session. If session exists, then it returns the reference of that session object, if not, this methods will return null. Q.19) Which syntax is correct to configure filter in web.xml A. < filter > < filter-name>r4rloginfilter</filter-name > < filter-class>com.acme.r4rloginfilter</filter-class > < /filter > B. < mapping-filter > < filter-name>r4rloginfilter</filter-name > < filter-class>com.acme.r4rloginfilter</filter-class > < / mapping-filter > C. < configure-filter > < filter-name>r4rloginfilter</filter-name > < filter-class>com.acme.r4rloginfilter</filter-class > < / configure-filter > D. < filters > < filter-name>r4rloginfilter</filter-name > < filter-class>com.acme.r4rloginfilter</filter-class > < /filters > ANSWER : < filter > < filter-name>r4rloginfilter</filter-name > < filter-class>com.acme.r4rloginfilter</filter-class > < /filter > Q.20) The init parameter name and value pairs that are defined in web.xml file are handled by A. ServletConfig object B. ServletContext object C. ServletRequest object D. ServletResponse object ANSWER : ServletConfig object ServletConfig :The object created after a servlet is instantiated and its default constructor is read. It is created to pass initialization information to the servlet. Q.21) Which object is used to forward the request processing from one servlet to another? A. ServeltContext B. ServletConfig C. RequestDispatcher D. ResponseDispatcher Page 5

6 ANSWER : RequestDispatcher Request Dispatcher is used to forward the request processing from one servlet to another. Q.22) The method forward(request,response) will A. Return back to the same method from where the forward was invoked B. Not return back to the same method from where the forward was invoked and the web pages navigation continues C. Both A and B are correct ANSWER : Return back to the same method from where the forward was invoked Forward request is used to forward to resources available within the server from where the call is made. This transfer of control is done by the container internally and browser / client is not involved. It return back to the same method from where the forward was invoked Q.23) init(),service() and destroy()methods are define in 1.javax.servlet.Servlet interface 2.javax.servlet.ServletHttp class 3.javax.servlet.ServletRequest interface 4.javax.servlet.ServletResponse interface A. 1,2,3,4,5 B. 1 C. 3,4,5 D. 1,4,5 ANSWER : 1 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. Q.24) Which of the following are class? 1.ServletContext 2.Servlet 3.GenericServlet 4.HttpServlet A. 1,2,3,4 B. 1,2 C. 3,4 D. 1,4 ANSWER : 3,4 javax.servlet.genericservlet Signature: public abstract class GenericServlet extends java.lang.object implements Servlet, ServletConfig, java.io.serializable GenericServlet defines a generic, protocol-independent servlet. GenericServlet gives a blueprint and makes writing servlet easier. GenericServlet provides simple versions of the lifecycle methods init and destroy and of the methods in the ServletConfig interface. GenericServlet implements the log method, declared in the ServletContext interface. Page 6

7 To write a generic servlet, it is sufficient to override the abstract service method. javax.servlet.http.httpservlet Signature: public abstract class HttpServlet extends GenericServlet implements java.io.serializable HttpServlet defines a HTTP protocol specific servlet. HttpServlet gives a blueprint for Http servlet and makes writing them easier. HttpServlet extends the GenericServlet and hence inherits the properties GenericServlet. Q.25) During initialization of servlet a servlet instance can throw A. An UnavailableException B. A ServletException C. Both D. None ANSWER : Both During initialization, the servlet instance can throw an UnavailableException or a ServletException. In this case, the servlet must not be placed into active service and must be released by the servlet container. The destroy method is not called as it is considered unsuccessful initialization. Q.26) Dynamic interception of requests and responses to transform the information is done by A. Servlet container B. Servlet config C. Servlet context D. Servlet filter ANSWER : Servlet filter Servlet filters can dynamically intercept requests and responses to transform or to use the information that is contained in the requests or responses. One or more servlet filters can be attached to a servlet or to a group of servlets. Servlet filters also can attach to JavaServer Pages (JSP) files and HTML pages. All of the attached servlet filters are called before the servlet is invoked. Both form-based login and servlet filters are supported by any servlet Version 2.3 specification-complaint Web container. The form login servlet performs the authentication and servlet filters perform additional authentication, auditing, or logging information. Page 7