Interview Questions
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1.What is JSP?

JavaServer Pages JSP is a technology for developing web pages that support dynamic content which helps developers insert java code in HTML pages by making use of special JSP tags, most of which start with <% and end with %>.

2.What are advantages of using JSP?

JSP offer several advantages as listed below:

  • Performance is significantly better because JSP allows embedding Dynamic Elements in HTML Pages itself.
  • JSP are always compiled before it's processed by the server unlike CGI/Perl which requires the server to load an interpreter and the target script each time the page is requested.
  • JavaServer Pages are built on top of the Java Servlets API, so like Servlets, JSP also has access to all the powerful Enterprise Java APIs, including JDBC, JNDI, EJB, JAXP etc.
  • JSP pages can be used in combination with servlets that handle the business logic, the model supported by Java servlet template engines.

3.What are the advantages of JSP over Active Server Pages ASP?

The advantages of JSP are twofold. First, the dynamic part is written in Java, not Visual Basic or other MS specific language, so it is more powerful and easier to use.
Second, it is portable to other operating systems and non-Microsoft Web servers.

4.What are the advantages of JSP over Pure Servlets?

It is more convenient to write andtomodify! regular HTML than to have plenty of println statements that generate the HTML. Other advantages are:

  • Embedding of Java code in HTML pages.
  • Platform independence.
  • Creation of database-driven Web applications.
  • Server-side programming capabilities.

5.What are the advantages of JSP over Server-Side Includes SSI?

SSI is really only intended for simple inclusions, not for "real" programs that use form data, make database connections, and the like.

6.What are the advantages of JSP over JavaScript?

JavaScript can generate HTML dynamically on the client but can hardly interact with the web server to perform complex tasks like database access and image processing etc.

7.What are the advantages of JSP over Static HTML?

Regular HTML, of course, cannot contain dynamic information.

8.Explain lifecycle of a JSP.?

A JSP Lifecycle consists of following steps:

  • Compilation: When a browser asks for a JSP, the JSP engine first checks to see whether it needs to compile the page. If the page has never been compiled, or if the JSP has been modified since it was last compiled, the JSP engine compiles the page.
  • The compilation process involves three steps:
    1.Parsing the JSP.
    2.Turning the JSP into a servlet.
    3.Compiling the servlet.
  • Initialization: When a container loads a JSP it invokes the jspInit method before servicing any requests
  • Execution: Whenever a browser requests a JSP and the page has been loaded and initialized, the JSP engine invokes the _jspService method in the JSP. The _jspService method of a JSP is invoked once per a request and is responsible for generating the response for that request and this method is also responsible for generating responses to all seven of the HTTP methods ie. GET, POST, DELETE etc.
  • Cleanup: The destruction phase of the JSP life cycle represents when a JSP is being removed from use by a container.The jspDestroy method is the JSP equivalent of the destroy method for servlets.

9.What is a sciptlet in JSP and what is its syntax?

A scriptlet can contain any number of JAVA language statements, variable or method declarations, or expressions that are valid in the page scripting language. Following is the syntax of Scriptlet:
<% code fragm ent %>

10.What are JSP declarations?

A declaration declares one or more variables or methods that you can use in Java code later in the JSP file. You must declare the variable or method before you use it in the JSP file.
<%! declaration; [ declaration; ]+ ... %>

11.What are JSP expressions?

A JSP expression element contains a scripting language expression that is evaluated, converted to a String, and inserted where the expression appears in the JSP file. The expression element can contain any expression that is valid according to the Java Language Specification but you cannot use a semicolon to end an expression. Its syntax is:
<%= expression %>

12.What are JSP comments?

JSP comment marks text or statements that the JSP container should ignore. A JSP comment is useful when you want to hide or "comment out" part of your JSP page. Following is the syntax of JSP comments:
<%-- This is JSP com m ent --%>

13.What are JSP Directives?

A JSP directive affects the overall structure of the servlet class. It usually has the following form:
<%@ directive attribute="value" %>

14.What are the types of directive tags?

The types directive tags are as follows:

  • <%@ page ... %> : Defines page-dependent attributes, such as scripting language, error page, and buffering requirements.
  • <%@ include ... %> : Includes a file during the translation phase.
  • <%@ taglib ... %> : Declares a tag library, containing custom actions, used in the page.

15.What are JSP actions?

JSP actions use constructs in XML syntax to control the behavior of the servlet engine. You can dynamically insert a file, reuse JavaBeans components, forward the user to another page, or generate HTML for the Java plugin. Its syntax is as follows:

16.Name some JSP actions.?

jsp:include, jsp:useBean,jsp:setProperty,jsp:getProperty, jsp:forward,jsp:plugin,jsp:element, jsp:attribute, jsp:body, jsp:text

17.What are JSP literals?

Literals are the values, such as a number or a text string, that are written literally as part of a program code. The JSP expression language defines the following literals:

  • Boolean: true and false
  • Integer: as in Java
  • Floating point: as in Java
  • String: with single and double quotes; " is escaped as \", ' is escaped as \', and \ is escaped as \\.
  • Null: null

18.What is a page directive?

The page directive is used to provide instructions to the container that pertain to the current JSP page. You may code page directives anywhere in your JSP page.

19.What are various attributes Of page directive?

Page directive contains the following 13 attributes.
1. language
2. extends
3. import
4. session
5. isThreadSafe
6. info
7. errorPage
8. isErrorpage
9. contentType
10. isELIgnored
11. buffer
12. autoFlush
13. isScriptingEnabled

20.What is a buffer attribute?

The buffer attribute specifies buffering characteristics for the server output response object.

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