Advance java session 4
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Client-side redirection uses response.sendRedirect() to instruct the client's browser to make a new request to a different URL. Server-side redirection uses the RequestDispatcher to forward or include content from another resource on the server. Forwarding transfers control to the new resource, while including renders the output of both resources. Redirection is commonly used for load balancing and sending clients to new locations.
Advance java session 4
- 1. Redirection
- 2. Agenda • Understanding Client side redirection • Understanding ServletContext • Understanding RequestDispatcher • Understanding Server Side Redirection • Difference between include and forward
- 3. What is Redirection • Page redirection is generally used when we need to - send the client to a new location - Load balancing
- 4. Types of Redirection • Two types of Redirection - Client side • Use request.sendRedirect • Use response.setStatus and response.setHeader - Server side • Use RequestDispatcher - include() - forward()
- 5. Client Redirection explained Client make original request for page1 Page1 contains redirecting response Redirecting response comes to the client Page1 is not displayed to the client Without user intervention it request page2 Page2 is ultimately displayed to the client
- 6. Understanding ServletContext • Only one ServletContext is created by container • Servlet’s instances can see its environment through ServletContext • It Contains method using which the servlets can communicate • It shares all the information required by the enitre application components(Servlets,JSP)
- 7. Understanding RequestDispatcher • RequestDispatcher Object forwards a client request to a resource or include resource itself in response back to the client. • Resource can be - Servlet - JSP - HTML
- 10. Understanding RequestDispatcher • RequestDispatcher can be created from - ServletContext - ServletRequest • Absolute URL can be specified only when RequestDispatcher invoked from ServletRequest
- 11. Difference between include and forward • Forward - Control is transferred to the new page - The output of the current page is not rendered • Include - Control is retained in the current page - The output of the current page is rendered along with the new page
- 12. Status Codes • response.setStatus(int statusCode) - Use a constant for the code, not an explicit int. - Constants are in HttpServletResponse - Names derived from standard message. - E.g., SC_OK, SC_NOT_FOUND, etc. • response.sendError(int code,String message) - Wraps message inside small HTML document • response.sendRedirect(String url) • Sets status code to 302 • Sets Location response header also
- 13. Summary • Response.sendRedirect does client side redirection • RequestDispatcher does Server Side redirection • Include will retain the control in the old page • Forward will transfer control to the new page