getInitParameter

[dh chau]

What is the difference between ServletConfig().getInitParameter() and ServletContext().getInitParameter()?
I don't know when to use ServletContext().getInitParameter(). From API of Sun, this fn returns a String containing the value of the named context-wide initialization parameter. What is the meaning context-wide initialization parameter?
Many thanks!!

[boyet silverio]

hi dh chau,
the getInitParameter of servletConfig is used to get the parameter values that were defined in the <init-param> tag of the <servlet> in web.xml e.g.

<web-app>
...
<servlet>
<servlet-name>YourServlet</serlvet-name>
<servlet-class>com.YourServlet</servlet-class>
<init-param>
<param-name>yourName</param-name>
<param-value>dh</param-value>
</init-param>
</servlet>
</web-app>

This params are available only inside the <servlet-class> specified i.e. com.DailyOvertimeServlet.
So inside this servlet, you can retrieve this initialization parameters using
...
String yourName = getServletConfig().getInitParameter("yourName");
...
For the getInitParameter of servletContext, it it used to get the parameter values that were defined in the
<context-param> tag under <web-app> in web.xml

e.g.
<web-app>
<context-param>
<param-name>companyName</param-name>
<param-value>The</param-value>
</context-param>
...
</web-app>

This context parameters are available to all servlets in your web-app i.e. context wide.
Thus, in ANY servlet in your web app, you can retrieve the context parameters using
...
String companyName = getServletContext().getInitParameter("companyName");
...
But don't just take my word on this, write some code, run, and see it happen.

[Hema Menon]

Related/Similar discussion here.
Hema