ServletContext.getRequestDispatcher() vs ServletRequest.getRequestDispatcher()

If you use an absolute path such as ("/index.jsp"), there is no difference.

If you use relative path, you must use HttpServletRequest.getRequestDispatcher(). ServletContext.getRequestDispatcher() doesn't allow it.

For example, if you receive your request on http://example.com/myapp/subdir,

    RequestDispatcher dispatcher = 
        request.getRequestDispatcher("index.jsp");
    dispatcher.forward( request, response ); 

Will forward the request to the page http://example.com/myapp/subdir/index.jsp.

In any case, you can't forward request to a resource outside of the context.

The request method getRequestDispatcher() can be used for referring to local servlets within single webapp.

Servlet context based getRequestDispatcher() method can used of referring servlets from other web applications deployed on SAME server.

request.getRequestDispatcher(“url”) means the dispatch is relative to the current HTTP request.Means this is for chaining two servlets with in the same web application Example

RequestDispatcher reqDispObj = request.getRequestDispatcher("/home.jsp");

getServletContext().getRequestDispatcher(“url”) means the dispatch is relative to the root of the ServletContext.Means this is for chaining two web applications with in the same server/two different servers

Example

RequestDispatcher reqDispObj = getServletContext().getRequestDispatcher("/ContextRoot/home.jsp");