JSP Interview Questions

What are Java Server Pages?

• JSP is an internal servlet.
• JSP is a server side technology.
• JSP creates dynamic web pages in the form of HTML as response.

What are the Literals in JSP?

• Null
• Boolean
• String
• Integer
• Float

What are the life cycle methods of JSP?

1. public void jspInit()
2. public void _jspService(ServletRequest request,ServletResponse) throws ServletException, IOException
3. public void jspDestroy()

Write JSP implicit Objects and their types?

1. out -> JspWriter
2. request -> HttpServletRequest
3. response -> HttpServletResponse
4. config -> ServletConfig
5. session -> HttpSession
6. application -> ServletContext
7. pageContext -> PageContext
8. page -> Object
9. exception -> Throwable

Differentiate Include Directive and Include Action?

• Include Directive:
  • Includes content at page translation time
  • Preferred in Static Pages
  • Includes Original content of the page
  • Cannot invoke include() method
  • Page size can be increased in the run-time
• Include Action:
  • Includes content at page request time
  • Preferred in Dynamic Pages
  • Does not include Original content of the page
  • Can invoke include() method
  • Page size is fixed

Explain JSP Action Tags?

• jsp:forward = Forward the request and response to another resource
• jsp:include = To include another Resource
• jsp:useBean = Locate/Create another bean object
• jsp:setProperty = Sets the property value in a bean object
• jsp:getPropety = Prints Property Value of the bean object
• jsp:fallback = Used to print a message if the plug in is working
• jsp:plugin = Used to embed another component such as an applet
• jsp:param = Sets the Parameter value

How to include static files in a JSP?

• Using include directive, we can include static page.
• This way the inclusion is performed in the translation phase once.
• The relative URL must be supplied for file attribute.

How can we avoid errors on display in a JSP Page?

• We need to setup an error JSP page.
• In the error JSP page set isErrorpage=”TRUE”.

Explain JSP Declaration?

• The declaration tag can be used to declare fields and methods in JSP code.
• The code written inside the JSP declaration is enclosed in <%!  %> tag.
• It is placed outside the service() method of the auto-generated servlet.

Differentiate “include directive” and “jsp:include action”?

• include directive the content to other resource is added to the generated servlet code at the time of translation
• include action happens at runtime.
• We can pass params to be used in the included resource with jsp:param action element
• In JSP include directive we can’t pass any params.

What is JSP Expression Language?

• We can use scriptlets and JSP expressions to retrieve attributes and parameters in JSP with java code and use it for view purpose.
• JSP Specs 2.0 introduced Expression Language (EL) through which we can get attributes and parameters easily using HTML like tags.
• Expression language syntax is ${name}.
• Expression language use implicit objects and EL operators to retrieve the attributes from different scopes and use them in JSP page.

What are the JSP custom tag components?

• JSP Custom Tag Handler
• Creating Tag Library Descriptor (TLD) File
• Deployment Descriptor Configuration for TLD

How JSP standard tags configure in web.xml?

• JSP standard tags do not configure in web.xml.
• Configure TLD files are inside the META-INF directory of the JSTL jar files.
• At the time of web application loading, container finds TLD files inside the META-INF directory and automatically configures them to be used directly in the application JSP pages.

What is use of scriptlet tag?

• A scriptlet is used to including java code in a JSP page.
• Syntax is <% Java Code %>

What are the different types of JSP tags?

• JSP standard tags
  • Scriptlet tags
  • Action tags
  • Directive tags
• Custom tags
• Presentation tags

What are the standard actions in JSP?

• <jsp: include>: Used to specify a response from the servlet or a JSP page into the current page.
• <jsp: forward>: Used to send a reply from the servlet/JSP page to another page.
• <jsp: useBean>: Allows a Java Bean to get accessible from a page and initializes the bean.
• <jsp: setProperty>: Used to set the Java Bean properties.
• <jsp: getProperty>: Fetches the property value from a Java Bean component and appends it to the response.
• <jsp: param>: Used with actions like <jsp:forward> and <jsp:, or plugin> to append a parameter to the request.
• <jsp: plugin>: Specifies whether to add a Java applet or a JavaBean to the current JSP page.

Define Expression tag in JSP?

• Expression tag is used to embed Java values directly in the output.
• It contains a scripting language expression that is classified, then converted to a string and then inserted where the phrase comes in JSP file.
• Its syntax is <%=expression%>.