RequestDispatcher clarfication

[Garlapati Ravi]

Hi All,

I need clarification:

<web-app>
 
<servlet>
<servlet-name>myservlet</servlet-name>
<servlet-class>com.ravi.sample.Sample</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>myservlet</servlet-name>
<url-pattern>/SuperServlet</url-pattern>
</servlet-mapping>
 
 
<servlet>
<servlet-name>myservlet1</servlet-name>
<servlet-class>com.ravi.sample.Sample1</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>myservlet1</servlet-name>
<url-pattern>/SuperServlet1</url-pattern>
</servlet-mapping>
 
</web-app>

getServletContext().getRequestDispatcher("/SuperServlet1");
request.getRequestDispatcher("/SuperServlet1");
request.getRequestDispatcher("SuperServlet1");

All the above 3 giving me the same result. i am unable to understand exactly how they(getServletContext() and request) differ.

Regards,
Ravi
[ May 03, 2008: Message edited by: Garla Ravi ]

[Musab Al-Rawi]

Hi,

You can create a RequestDispatcher in either way. If your Servlet doesn't extend HttpServlet then the only way to get a RequestDispatcher is thought the ServletContext.

when you get a RequestDispatcher throught ServletContext then you MUST start the path with a /. the path is treated as relative to the current context root.
you cah check the API

[Shiraz Khan]

When you get a request dispatcher from servlet context, you have to start the path with a "/" because here there is no concept of any relative path. The container will look for the resource with respect to the application root.

When you get a request dispatcher from request then, you can give the resource path with or without "/" because here there is concept of relative path (relative to the request coming from the client). If the resource path starts with a "/" then the container will look from the app root. If the resource path is without "/" the container will look with respect to the request path.

[Garlapati Ravi]

Thanks for your replies, but i am not quite convinced with your answers, as i found similar replies when i google. Requesting for appropriate reply, which is not covered in book or in APIs.

Fist I will put on what i understood.

getServletContext().getRequestDispatcher("/SuperServlet1");
request.getRequestDispatcher("SuperServlet1");

There is absolutely no difference between above two, apart from objects which the getRequestDispatcher() method is called.

From my example relative/logical paths are no were given importance, they are treated as same.

am i correct ? please clarify.