Response如何实现重定向

　　@WebServlet(value = "/b")

　　public class BServlet extends HttpServlet {

　　@Override

　　protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

　　//重定向通过请求方式获取数据

　　String username=req.getParameter("username");

　　System.out.println(username);

　　}

　　@Override

　　protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

　　doGet(req,resp);

　　}

　　}