Jsp parameters scop

What is the difference between request.sendRedirect()

and

requestDispatcher.forward()

in terms 开发者_JS百科of request parameters?

Forward

* a forward is performed internally by the servlet
* the browser is completely unaware that it has taken place, so its original URL remains intact
* any browser reload of the resulting page will simple repeat the original request, with the original URL

Redirect

* a redirect is a two step process, where the web application instructs the browser to fetch a second URL, which differs from the original
* a browser reload of the second URL will not repeat the original request, but will rather fetch the second URL
* redirect is marginally slower than a forward, since it requires two browser requests, not one
* objects placed in the original request scope are not available to the second request

see here