How to pass information from JSP to included JSP?- Using <%jsp:param> tag.
What is the difference between directive include and jsp include?- <%@ include>: Used to include static resources during translation time. JSP include: Used to include dynamic content or static content during runtime.
What is the difference between RequestDispatcher and sendRedirect?- RequestDispatcher: server-side redirect with request and response objects. sendRedirect : Client-side redirect with new request and response objects.
How does JSP handle runtime exceptions?- Using errorPage attribute of page directive and also we need to specify isErrorPage=true if the current page is intended to URL redirecting of a JSP.
How do you delete a Cookie within a JSP?
Cookie mycook = new Cookie(\"name\",\"value\"); response.addCookie(mycook); Cookie killmycook = new Cookie(\"mycook\",\"value\"); killmycook.setMaxAge(0); killmycook.setPath(\"/\"); killmycook.addCookie(killmycook);
How do I mix JSP and SSI #include?- If you’re just including raw HTML, use the #include directive as usual inside your .jsp file.
<!--#include file="data.inc"-->
But it’s a little trickier if you want the server to evaluate any JSP code that’s inside the included file. If your data.inc file contains jsp code you will have to use
<%@ vinclude="data.inc" %>
The <!–#include file="data.inc"–> is used for including non-JSP files.
I made my class Cloneable but I still get Can’t access protected method clone. Why?- Some of the Java books imply that all you have to do in order to have your class support clone() is implement the Cloneable interface. Not so. Perhaps that was the intent at some point, but that’s not the way it works currently. As it stands, you have to implement your own public clone() method, even if it doesn’t do anything special and just calls super.clone().
Why is XML such an important development?- It removes two constraints which were holding back Web developments: dependence on a single, inflexible document type (HTML) which was being much abused for tasks it was never designed for; the complexity of full SGML, whose syntax allows many powerful but hard-to-program options. XML allows the flexible development of user-defined document types. It provides a robust, non-proprietary, persistent, and verifiable file format for the storage and transmission of text and data both on and off the Web; and it removes the more complex options of SGML, making it easier to program for.
What is the fastest type of JDBC driver?- JDBC driver performance will depend on a number of issues:
the quality of the driver code,
the size of the driver code,
the database server and its load,
network topology,
the number of times your request is translated to a different API.
In general, all things being equal, you can assume that the more your request and response change hands, the slower it will be. This means that Type 1 and Type 3 drivers will be slower than Type 2 drivers (the database calls are make at least three translations versus two), and Type 4 drivers are the fastest (only one translation).
How do I find whether a parameter exists in the request object?
boolean hasFoo = !(request.getParameter(\"foo\") == null || request.getParameter(\"foo\").equals(\"\"));
or
boolean hasParameter = request.getParameterMap().contains(theParameter); //(which works in Servlet 2.3+)
How can I send user authentication information while makingURLConnection?- You’ll want to use HttpURLConnection.setRequestProperty and set all the appropriate headers to HTTP authorization.
What is JSP? Describe its concept. JSP is a technology that combines HTML/XML markup languages and elements of Java programming Language to return dynamic content to the Web client, It is normally used to handle Presentation logic of a web application, although it may have business logic.
What are the lifecycle phases of a JSP?
JSP page looks like a HTML page but is a servlet. When presented with JSP page the JSP engine does the following 7 phases.
Page translation: -page is parsed, and a java file which is a servlet is created.
Page compilation: page is compiled into a class file
Page loading : This class file is loaded.
Create an instance :- Instance of servlet is created
jspInit() method is called
_jspService is called to handle service calls
_jspDestroy is called to destroy it when the servlet is not required.
What is a translation unit? JSP page can include the contents of other HTML pages or other JSP files. This is done by using the include directive. When the JSP engine is presented with such a JSP page it is converted to one servlet class and this is called a translation unit, Things to remember in a translation unit is that page directives affect the whole unit, one variable declaration cannot occur in the same unit more than once, the standard action jsp:useBean cannot declare the same bean twice in one unit.
How is JSP used in the MVC model? JSP is usually used for presentation in the MVC pattern (Model View Controller ) i.e. it plays the role of the view. The controller deals with calling the model and the business classes which in turn get the data, this data is then presented to the JSP for rendering on to the client.
What are context initialization parameters? Context initialization parameters are specified by the <context-param> in the web.xml file, these are initialization parameter for the whole application and not specific to any servlet or JSP.
What is a output comment? A comment that is sent to the client in the viewable page source. The JSP engine handles an output comment as un-interpreted HTML text, returning the comment in the HTML output sent to the client. You can see the comment by viewing the page source from your Web browser.
What is a Hidden Comment? A comment that documents the JSP page but is not sent to the client. The JSP engine ignores a hidden comment, and does not process any code within hidden comment tags. A hidden comment is not sent to the client, either in the displayed JSP page or the HTML page source. The hidden comment is useful when you want to hide or “comment out” part of your JSP page.
What is a Expression? Expressions are act as place holders for language expression, expression is evaluated each time the page is accessed.
What is a Declaration? It declares one or more variables or methods for use later in the JSP source file. A declaration must contain at least one complete declarative statement. You can declare any number of variables or methods within one declaration tag, as long as semicolons separate them. The declaration must be valid in the scripting language used in the JSP file.
What is a Scriptlet? A scriptlet can contain any number of language statements, variable or method declarations, or expressions that are valid in the page scripting language. Within scriptlet tags, you can declare variables or methods to use later in the file, write expressions valid in the page scripting language, use any of the JSP implicit objects or any object declared with a <jsp:useBean>.
What are the implicit objects? List them. Certain objects that are available for the use in JSP documents without being declared first. These objects are parsed by the JSP engine and inserted into the generated servlet. The implicit objects are:
request
response
pageContext
session
application
out
config
page
exception
What’s the difference between forward and sendRedirect? When you invoke a forward request, the request is sent to another resource on the server, without the client being informed that a different resource is going to process the request. This process occurs completely with in the web container And then returns to the calling method. When a sendRedirect method is invoked, it causes the web container to return to the browser indicating that a new URL should be requested. Because the browser issues a completely new request any object that are stored as request attributes before the redirect occurs will be lost. This extra round trip a redirect is slower than forward.
What are the different scope values for the <jsp:useBean>? The different scope values for <jsp:useBean> are:
page
request
session
application
Why are JSP pages the preferred API for creating a web-based client program? Because no plug-ins or security policy files are needed on the client systems(applet does). Also, JSP pages enable cleaner and more module application design because they provide a way to separate applications programming from web page design. This means personnel involved in web page design do not need to understand Java programming language syntax to do their jobs.
Is JSP technology extensible? Yes, it is. JSP technology is extensible through the development of custom actions, or tags, which are encapsulated in tag libraries.
What is difference between custom JSP tags and beans? Custom JSP tag is a tag you defined. You define how a tag, its attributes and its body are interpreted, and then group your tags into collections called tag libraries that can be used in any number of JSP files. Custom tags and beans accomplish the same goals — encapsulating complex behavior into simple and accessible forms. There are several differences:
Custom tags can manipulate JSP content; beans cannot.
Complex operations can be reduced to a significantly simpler form with custom tags than with beans.
Custom tags require quite a bit more work to set up than do beans.
Custom tags usually define relatively self-contained behavior, whereas beans are often defined in one servlet and used in a different servlet or JSP page.
Custom tags are available only in JSP 1.1 and later, but beans can be used in all JSP 1.x versions.
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