/*
	在config文件夾下編寫配置類
 實現WebMvcConfigurer接口，擴展MVC功能
 測試前將LoginController控制類注釋，更好的觀察效果
 */
@Configuration
public class MyMVCConfig implements WebMvcConfigurer {
 //添加視圖管理
 @Override
 public void addViewControllers(ViewControllerRegistry registry) {
  // 請求toLoginPage映射路徑或者login.html頁面都會自動映射到login.html頁面
  registry.addViewController("/toLoginPage").setViewName("login");
  registry.addViewController("/login.html").setViewName("login");
 }
}

/*
 自定義一個攔截器類，實現簡單的攔截業(yè)務
 */
@Configuration
public class MyInterceptor implements HandlerInterceptor {
 @Override
 public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
  // 用戶請求/admin開頭路徑時，判斷用戶是否登錄
  String uri = request.getRequestURI();
  Object loginUser = request.getSession().getAttribute("loginUser");
  if(uri.startsWith("/admin")&&null==loginUser){
   response.sendRedirect("/toLoginPage");
   return false;
  }
  return true;
 }

 @Override
 public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,@Nullable ModelAndView modelAndView) throws Exception {
  //向request域中存放當前年份用于頁面動態(tài)展示
  request.setAttribute("currentYear", Calendar.getInstance().get(Calendar.YEAR));
 }

 @Override
 public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

 }
}

 @Autowired
 private MyInterceptor myInterceptor;
 //添加攔截器管理
 @Override
 public void addInterceptors(InterceptorRegistry registry) {
  registry.addInterceptor(myInterceptor)
    .addPathPatterns("/**")
    .excludePathPatterns("/login.html");
 }

/*
 自定義Servlet類
 使用@Component注解將MyServlet類作為組件注入Spring容器。該類繼承自HTTPServlet，
 通過HttpServletResponse對象向頁面輸出"hello MyServlet"
 */
@Component
public class MyServlet extends HttpServlet {
 @Override
 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  this.doPost(req,resp);
 }

 @Override
 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  resp.getWriter().write("hello MyServlet");
 }
}

/*
 嵌入式Servlet容器三大組件配置
 @Configuration注解將該類標注為配置類，getServlet()方法用于注冊自定義MyServlet，
 返回ServletRegistrationBean類型的Bean對象
 */
@Configuration
public class ServletConfig {
 // 注冊Servlet組件
 @Bean
 public ServletRegistrationBean<javax.servlet.Servlet> getServlet(MyServlet myServlet){
  return new ServletRegistrationBean<javax.servlet.Servlet>(myServlet,"/myServlet");
 }
}

/*
 自定義Filter類
 使用@Component注解將當前MyFilter類作為組件注入到Spring容器中
 MyFilter類實現Filter接口，重寫如下三個方法，在doFilter()方法中想控制臺打印"hello MyFilter"
 */
@Component
public class MyFilter implements Filter {
 @Override
 public void init(FilterConfig filterConfig) throws ServletException {
 }
 @Override
 public void destroy() {
 }
 @Override
 public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
  System.out.println("hello MyFilter");
  filterChain.doFilter(servletRequest,servletResponse);
 }
}

 //注冊Filter組件
 @Bean
 public FilterRegistrationBean<javax.servlet.Filter> getFilter(MyFilter myFilter){
  FilterRegistrationBean<javax.servlet.Filter> registrationBean = new FilterRegistrationBean<>(myFilter);
  registrationBean.setUrlPatterns(Arrays.asList("/toLoginPage","/myFilter"));
  return registrationBean;
 }

/*
 自定義Listener類
 */
@Component
public class MyListener implements ServletContextListener {
 @Override
 public void contextInitialized(ServletContextEvent sce) {
  System.out.println("contextInitialized ...");
 }

 @Override
 public void contextDestroyed(ServletContextEvent sce) {
  System.out.println("contextDestroyed ...");
 }
}

 //注冊Listener組件
 @Bean
 public ServletListenerRegistrationBean<java.util.EventListener> getServletListener(MyListener myListener){
  return new ServletListenerRegistrationBean<>(myListener);
 }