servlet3.0IDEA注解使用

servlet3.0 可以使用注解，而不用去配置web.xml文件

@webServlet(name="名称",urlPatterns="访问路径")

@WebServlet(name = "BServlet",urlPatterns = "/BServlet")
public class BServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username=request.getParameter("username");
        System.out.println("username"+username);
        request.getSession().setAttribute("username",username);
        response.sendRedirect("char.jsp");
    }