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What is the query used to retrieve all the table names on SQL Server (Query analyzer)? Is it possible implement an interface in a JSP? Give all the different scope values for <jsp:useBean> tag.- The query that we have to use is : select * from information _ schema.tables - An interface cannot be implemented in jsp. - <jsp:useBean> tag is used for using any java object in a jsp page. - The scope values for <jsp:useBean> tag are listed below : 1. Page 2. Request 3. Session 4. Application
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Explain the difference between ServletContext and PageContext. How to create request.getRequestDispatcher () and context.getRequestDispatcher()?- The ServletContext : Provides the information about the container.
- PageContext : Provides the information about the Request.
- To create request.getRequestDispatcher(path) we have to provide the relative path of the resource. But to create context.getRequestDispatcher (path) we have to provide the absolute path of the resource.
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How to pass the information from the the JSP to the included JSP? Explain the difference between directive include and jsp include.- We can pass the information from the JSP to the included JSP by the Using <%jsp:param> tag.
- During passing the information <%@ include> may be used for including the static resources.
- During translation time the JSP include is used for including the dynamic programming.
- Directive include is used for including the non-JSP file contents or static contents during runtime.
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Explain the difference between RequestDispatcher and sendRedirect? How JSP handles runtime exceptions?- RequestDispatcher redirects the server-side by requesting and responding the objects. But sendRedirect redirects the Client-side with new request and responding the objects.
- JSP handles runtime exceptions by using the errorPage attribute of the page directive.
- By specifying ErrorPage = true the current page intended URL is redirected to the JSP.
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How to delete a Cookie in a JSP?- The following code explain how to delete a Cookie in a JSP : Cookie mycook = new Cookie("name1","value1");
response.addCookie(mycook1);
Cookie killmycook = new Cookie("mycook1","value1");
killmycook . set MaxAge ( 0 );
killmycook . set Path (" / ");
killmycook . addCookie ( killmycook 1 );
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How we will be able to intersect JSP and SSI #include?- To intersect the JSP and the SSI #include we have to make class Cloneable. - But still we will not be able to access the protected method clone. - So we have to include a raw HTML, using the #include directive inside our .jsp file. - Code :<!--#include file="data.inc"--> - The server will be able to evaluate various JSP codes inside the included file by using the following code : <%@ include="data.inc" %> But, the <!–#include file="data.inc"–> is mainly used for including the non-JSP files.
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Explain the types of JSP actions.- JSP actions are mainly XML tags which directs the server for using existing components or for controlling the behavior of the JSP engine.
- JSP Actions mainly comprises of a typical (XML-based) prefix of "jsp" followed by a colon( : ), following by the action name & followed by one or more attribute parameters.
- The six JSP Actions are:
1. <jsp:include/>
2. <jsp:forward/>
3. <jsp:plugin/>
4. <jsp:usebean/>
5. <jsp:setProperty/>
6. <jsp:getProperty/>
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Give the basic differences between <jsp:include page = ... > and <%@ include file = ... >?- Both the tag helps to include the information from one page to another.
<jsp:include page = ... >
- This is a kind of a function call from one jsp to another jsp.
- It is executed whenever the client accesses the client page.
- This approach is useful for modularizing of the web applications.
<%@ include file = ... >:
- The content of the included file is textually embedded in the page that has <%@ include file=".."> directive.
- By this the included file will be changed and the changed content can not be included in the output.
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Explain the differences between <jsp:forward page = ... > and response.sendRedirect(url).<jsp:forward page = ... >
- The <jsp:forward> element propagates the request object containing the client request information from one JSP file to another file.
- The target file might be an HTML file, another JSP file, or any servlet, but it must be in the same application context.
response.sendRedirect(url)
- The sendRedirect helps to send HTTP temporary redirect response to the browser, and the browser helps to create a new request for going to the redirected page.
- The response.sendRedirect helps to kill the session variables.
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Explain the advantages of JSP.- JSP is an embedded Java code in HTML pages. - JSP is Platform independent. - JSP creates database-driven Web applications. - JSP enables Server-side programming capabilities. How to embed the Java code in the HTML pages.The code below explains it : < % @ page language = " java " %>
<HTML>
<HEAD><TITLE>RESULT PAGE</TITLE></HEAD>
<BODY>
<%
PrintWriter print = request . get Writer ( ) ;
print . println ( " Welcome buddy !!!" );
%>
</BODY>
</HTML>
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What are the implicit Objects available?- Implicit objects are valid for only JSP pages.
- The web container creates it.
- It comprises the information related to a specific request, page & application.
- The JSP implicit objects are tabulated below :
1. Variable
2. Class
3. Description
- application(javax.servlet.ServletContext) : The context for the JSP page's servlet and any Web components contained in the same application.
- config(javax.servlet.ServletConfig) : Initialization information for the JSP page's servlet.
- exception(java.lang.Throwable) : Accessible only from an error page.
- out(javax.servlet.jsp.JspWriter) : The output stream.
- page(java.lang.Object) : The instance of the JSP page's servlet processing the current request. Not typically used by JSP page authors.
- pageContext(javax.servlet.jsp.PageContext) : The context for the JSP page. Provides a single API to manage the various scoped attributes.
- request(Subtype of javax.servlet.ServletRequest) : The request triggering the execution of the JSP page.
- response(Subtype of javax.servlet.ServletResponse) : The response to be returned to the client. Not typically used by JSP page authors.
- session(javax.servlet.http.HttpSession) : The session object for the client.
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What do you mean by JSP o/p Comments?- JSP Output Comments are visible in HTML source file. - Code :<!-- This file displays the user login screen -->
<!-- This page was loaded on
<%= (new java.util.Date()).toLocaleString() %> --> What is expression in the JSP? What is a JSP Scriplet?- The expression is a tag used for inserting Java values directly into the output. - The Syntax is given as: <%= expression %> - The expression is explained by the code below : <%
String userName=null;
userName=request.getParameter("userName");
%> - An expression tag comprises of scripting language expressions that is evaluated & converted to a String, and is being inserted where the expression appears in the JSP file. - The expression tag following displays time on the output: <%=new java.util.Date()%> Scriplet :- JSP Scriplet is a jsp tag which is used for enclosing a java code in the JSP pages. - Scriplet begins with <% tag and ends with %> tag.
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What is JSP Declaratives?- JSP Decleratives are the JSP tags which are used for declaring the variables. - Declaratives are stored in the <%! %> tag and ends with a semi-colon( ; ). - The variables and functions reside within the declaration tag and can be used anywhere in the JSP. - The code of Declaratives : <%@page contentType="text/html" %> <html> <body> <%! int cnt=0; private int getCount() { //increment cnt and return the value cnt++; return cnt; } %> <p>Values of Cnt are:</p> <p><%=getCount()%></p> </body> </html>
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Explain the life-cycle methods of JSP?- The life-cycle methods of the JSP are detailed below :
jspInit() :
- The container calls the jspInit() for initializing the servlet instance.
- It is called before any other method, and is called only once for a servlet instance.
jspService() :
- The container calls the _jspservice() for each request and passes the request and the response objects.
- jspService() method can not be overridden.
jspDestroy() :
- The container calls jspDestroy() when its instance is about to be destroyed.
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