其将会在服务器启动时被tomcat容器处理，容器将根据具体的属性配置将相应的类部署为 Servlet。
@WebServlet( name = "UserServlet", value = { "/servlet/LoginServlet" }, initParams = { @WebInitParam(name = "username", value = "Jack") } ) public class LoginServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String username = request.getParameter("username"); String password = request.getParameter("password"); if ("admin".equals(username) && "admin".equals(password)) { request.getSession().setAttribute("username", "admin"); request.getSession().setAttribute("password", "admin"); response.sendRedirect("../sucess.jsp"); } else { response.sendRedirect("../failed.jsp"); } } }
@WebFilter(filterName = "LoginFilter", urlPatterns = "/*", //对所有url进行过滤 initParams = {@WebInitParam(name = "url", value = "index.jsp;LoginServlet;error.jsp"), @WebInitParam(name = "encoding", value = "UTF-8")})
