Java Reference
In-Depth Information
The
ServletConfig
object can be used to do the following:
Pass deploy-time information to the servlet (such as a database or enterprise
bean lookup name) that you do not want to hard-code into the servlet. This
deploy-time information is called the
servlet init parameters
. The servlet init
parameters will be discussed in the next section.
ServletContext
.
The
ServletContext
object can be used to do the following:
Access the web application parameters
Access the
Set attributes that all components of the application can access
Get server information, including the name and version of the container and the
version of the API that is supported
A servlet can have three types of parameters:
Request parameters
Initialization (init) parameters
Context-initialization (context-init) parameters
Initialization Parameters
The initialization parameters are defined in the
web.xml
file, as illustrated in Listing 2-5.
Listing 2-5. Defining Initialization Parameters
<servlet>
<init-param>
<param-name>email </param-name>
<param-value>
vishalway@.gmail.com
<
/param-value>
</init-param>
</servlet>
You cannot use
init-parameters
until the servlet is initialized. Your servlet inherits
getServletConfig()
, so you can call that from any method in your servlet to get a reference to a
ServletConfig
. Once you have a
ServletConfig
reference, you can call
getInitParam()
.
When the container initializes a servlet, the following happens:
The container makes a unique
ServletConfig
for the servlet.
1.
2.
The container reads the init parameters from the deployment descriptor and
sets them in the
ServletConfig
object.
The container then passes the
ServletConfig
to the servlet's
init
(servletConfig)
method.
3.