Difference
between ServletConfig
and
ServletContext
ServletContext and ServletConfig these two
are important interface of Servlet API which is used by Java J2EE programmer
during web application development. Correct understanding of What is ServletContext and ServletConfig is very
important for any J2EE application developer. Apart from that Difference
between ServletContext and ServletConfig are a popular
Servlet JSP interview questions and mostly asked on both fresher and
experienced Java programmer during J2EE interviews. Both ServletContext and ServletConfig
are basically configuration objects which are used by servlet container
to initialize various parameter of web application. But they have some
difference in terms of scope and availability so first we see what is ServletContext and ServletConfig objects
are and then we will see difference
between ServletConfig and ServletContext in Java
J2EE.
What
is ServletConfig in JSP Servlet
ServletConfig
in an interface in Servlet API and ServletConfig object
represents or used to initialize single servlet in web
application by servlet container. Inside deployment descriptor known as web.xml, we define Servlet initialization parameter
related to that servlet inside <init-param></init-param>
tag. its a set of name /value pair. Following is signature of ServletConfig
interface :
public interface ServletConfig
By using ServletConfig and combination of init-param you can
configure any Servlet in J2EE environment.
What
is ServletContext in Servlet JSP
ServletContext is even more important than ServletConfig and its
one per web application, also known as Context. This
object is common for all the servlet and they use this object to communicate
with the servlet container to get the detail of whole web application or
execution environment important thing to remember is, it represents a web
application in single JVM.
Signature:
public interface ServletContext
By using ServletContext object you can share objects to any Servlet or
JSP in whole web application. See how
to get ServletContext in Servlet JSP and Struts to find out different ways
of getting ServletContext in J2EE application.
Difference between ServletContext vs ServletConfig
Now let’s see difference between ServletContext and ServletConfig
in Servlets JSP in tabular format
Servlet
Config
|
Servlet
Context
|
Servlet config object represent single servlet
|
It represent whole web application running on particular JVM and common
for all the servlet
|
Its like local parameter associated with particular servlet
|
Its like global parameter associated with whole application
|
It’s a name value pair defined inside the servlet section of web.xml
file so it has servlet wide scope
|
ServletContext has application wide scope so
define outside of servlet tag in web.xml file.
|
getServletConfig() method is used to get the
config object
|
getServletContext() method is used to get the context object.
|
for example shopping cart of a user is a specific to particular user so
here we can use servlet config
|
To get the MIME type of a file or application session related
information is stored using servlet context object.
|
That’s all on What is ServletContext, What is ServletConfig and What are
differences between ServletContext and ServletConfig in J2EE environment. Most important difference to remember is that ServletContext is per web
application while ServletConfig is per servlet basis. ServletContext is also
refer as application
scope in JSP
Further Learning
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