简介

SpringBoot可以简化开发流程，但是在其中如何使用传统的J2EE servlet/listener/filter呢

@Bean配置

在Configuration类中加入filter和servlet的registration

@Bean    public FilterRegistrationBean registFilter() {        FilterRegistrationBean registration = new FilterRegistrationBean();        registration.setFilter(new Filter(){            @Override            public void init(FilterConfig filterConfig) throws ServletException {            }            @Override            public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {                System.out.println("in filter");                chain.doFilter(request, response);            }            @Override            public void destroy() {            }                    });        registration.addUrlPatterns("/*");        registration.setOrder(1);        return registration;    }         @SuppressWarnings("serial")    @Bean    public ServletRegistrationBean registServlet() {        ServletRegistrationBean servletRegist=new ServletRegistrationBean();        servletRegist.setServlet(new HttpServlet (){            @Override            protected void doGet(HttpServletRequest req, HttpServletResponse resp)                    throws ServletException, IOException {                resp.getWriter().write("inside servlet");            }        });        servletRegist.addUrlMappings("/registedServlet");        return servletRegist;    }

运行项目就可以访问servlet和filter了，在registrationBean中可以配置路径和实例。

使用Servlet3.0

如果使用Servlet3.0的话，可以在Configuration类上加@ServletComponentScan("类路径")

并开发对应的filter、listener、servlet

@WebFilterpublic class CustFilter implements Filter{    @Override    public void init(FilterConfig filterConfig) throws ServletException {        // TODO Auto-generated method stub            }    @Override    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {        System.out.println("in filter2");        chain.doFilter(request, response);    }    @Override    public void destroy() {        // TODO Auto-generated method stub            }}@WebListenerpublic class CustListener implements HttpSessionListener {    @Override    public void sessionCreated(HttpSessionEvent se) {        System.out.println("session created");    }    @Override    public void sessionDestroyed(HttpSessionEvent se) {        // TODO Auto-generated method stub    }}@WebServlet(urlPatterns={"/cust"})public class CustServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        req.getSession().setAttribute("a", "1");        resp.getWriter().write("cust servlet");    }}

在访问localhost:8080/cust时，对应的filter、listener、servlet都会被访问到