| | | | | | Question Answer Tutorial - JAVA->SERVLET | | | | | | | Question: 11.What is difference between ServletConfig and ServletContext?
| | | Answer: Some of the differences between ServletConfig and ServletContext&
nbsp;are:/>1.) ServletConfig is a unique object per servlet whereas&n
bsp;ServletContext is a unique object forcomplete application/>/>2.) ServletConfig is used to provide init parameters to&nb
sp;the servlet whereas ServletContext is used/>to provide application level init parameters that all othe
r servlets can use/>3.) We can’t set attributes in ServletConfig object wherea
s we can set attributes in ServletContext/>that other servlets can use in their implementation
| | | | | | | | | | | | Question: 12.What is Request Dispatcher?
| | | Answer: RequestDispatcher interface is used to forward the request t
o another resource that can be HTML, JSP/>or another servlet in same application. We can also u
se this to include the content of another/>resource to the response. This interface is used for
inter-servlet communication in the samecontext/>There are two methods defined in this interface:/>1.) void forward(ServletRequest request, ServletResponse response) –
forwards the request from a/>servlet to another resource (servlet, JSP file, or HTML&nb
sp;file) on the server/>2.) void include(ServletRequest request, ServletResponse response) –
includes the content of a/>resource (servlet, JSP page, HTML file) in the response/>/>We can get RequestDispatcher in a servlet using ServletCon
text getRequestDispatcher(String path)/>method. The path must begin with a / and is inte
rpreted as relative to the current context root
| | | | | | | | | | | | | Question: What is difference between PrintWriter and ServletOutputStream?
| | | Answer: PrintWriter is a character-stream class whereas ServletOutputStream&nb
sp;is a byte-stream class. We can/>use PrintWriter to write character based information such
as character array and String to the/>response whereas we can use ServletOutputStream to write b
yte array data to the response./>We can use ServletResponse getWriter() to get the PrintWri
ter instance whereas we can use/>ServletResponse getOutputStream() method to get the ServletOutputStr
eam object reference
| | | | | | | | | | | | Question: Can we get PrintWriter and ServletOutputStream both in a servlet?
| | | Answer: We can’t get instances of both PrintWriter and ServletOutput
Stream in a single servlet method, if we/>invoke both the methods; getWriter() and getOutputStream() on&n
bsp;response; we will get/>java.lang.IllegalStateException at runtime with message as other&nbs
p;method has already been called forthis response
| | | | | | | | | | | | Question: How can we create deadlock situation in servlet?
| | | Answer: We can create deadlock in servlet by making a loop
;of method invocation, just call doPost() method/>from doGet() method and doGet() method to doPost() method&
nbsp;to create deadlock situation in servlet.
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