What is the difference between sendRedirect & forward methods

What is the difference between sendRedirect & forward methods?

Forward( ) : javax.Servlet.RequestDispatcher interface.
- RequestDispatcher.forward( ) works on the Server.
- The forward( ) works inside the WebContainer.
- The forward( ) restricts you to redirect only to a resource in the same web-Application.
- After executing the forward( ), the control will return back to the same method from where the forward method was called.
- The forward( ) will redirect in the application server itself, it does'n come back to the client.
- The forward( ) is faster than Sendredirect( ) .

To use the forward( ) of the requestDispatcher interface, the first thing to do is to obtain RequestDispatcher Object. The Servlet technology provides in three ways.

1. By using the getRequestDispatcher( ) of the javax.Servlet.ServletContext interface , passing a String containing the path of the other resources, path is relative to the root of the ServletContext.
RequestDispatcher rd=request.getRequestDispatcher ("secondServlet");
Rd.forward(request, response);

2. getRequestDispatcher( ) of the javax.Servlet.Request interface , the path is relative to current HtpRequest.
RequestDispatcher rd=getServletContext( ).getRequestDispatcher("servlet/secondServlet");
Rd.forward(request, response);

3. By using the getNameDispatcher( ) of the javax.Servlet.ServletContext interface.
RequestDispatcher rd=getServletContext( ).getNameDispatcher("secondServlet");
Rd.forward(request, response);

Sendredirect( ) : javax.Servlet.Http.HttpServletResponce interface
- RequestDispatcher.SendRedirect( ) works on the browser.
- The SendRedirect( ) allows you to redirect trip to the Client.
- The SendRedirect( ) allows you to redirect to any URL.
- After executing the SendRedirect( ) the control will not return back to same method.
- The Client receives the Http response code 302 indicating that temporarly the client is being redirected to the specified location , if the specified location is relative , this method converts it into an absolute URL before redirecting.
- The SendRedirect( ) will come to the Client and go back,.. ie URL appending will happen.

Response. SendRedirect( "absolute path");
Absolutepath – other than application , relative path - same application.

When you invoke a forward request, the request is sent to another resource on the server, without the client being informed that a different resource is going to process the request. This process occurs completely with in the web container. When a sendRedirtect method is invoked, it causes the web container to return to the browser indicating that a new URL should be requested. Because the browser issues a completely new request any object that are stored as request attributes before the redirect occurs will be lost. This extra round trip a redirect is slower than forward.

OR

forward

Control can be forward to resources available within the server from where the call is made. This transfer of control is done by the container internally and browser / client is not involved. This is the major difference between forward and sendRedirect. When the forward is done, the original request and response objects are transfered along with additional parameters if needed.

redirect

Control can be redirect to resources to different servers or domains. This transfer of control task is delegated to the browser by the container. That is, the redirect sends a header back to the browser / client. This header contains the resource url to be redirected by the browser. Then the browser initiates a new request to the given url. Since it is a new request, the old request and response object is lost.

For example, sendRedirect can transfer control from http://javapapers.com to http://anydomain.com but forward cannot do this.

’session’ is not lost in both forward and redirect.

To feel the difference between forward and sendRedirect visually see the address bar of your browser,
in forward, you will not see the forwarded address (since the browser is not involved)
in redirect, you can see the redirected address.