import javax.servlet.*;
import java.io.IOException;
public class MyFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        // do something 處理request 或response
        System.out.println("filter1");
        // 調(diào)用filter鏈中的下一個(gè)filter
        filterChain.doFilter(servletRequest,servletResponse);
    }
    @Override
    public void destroy() {
    }
}

@Configuration
public class FilterConfig {
    @Bean
    public FilterRegistrationBean registrationBean() {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(new MyFilter());
        filterRegistrationBean.addUrlPatterns("/*");
        filterRegistrationBean.setOrder(1);//定義過濾器的執(zhí)行先后順序  值越小越先執(zhí)行 不影響B(tài)ean的加載順序
        return filterRegistrationBean;
    }
}

// 注入spring容器
@Order(1)//定義過濾器的執(zhí)行先后順序  值越小越先執(zhí)行 不影響B(tài)ean的加載順序
@Component
// 定義filterName 和過濾的url
@WebFilter(filterName = "my2Filter" ,urlPatterns = "/*")
public class My2Filter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("filter2");
    }
    @Override
    public void destroy() {
    }
}

public class MyInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle");
        return true;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle");
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
        System.out.println("afterCompletion");
    }
}

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new MyInterceptor());
    }
}

/**
 * 上下文監(jiān)聽器，在服務(wù)器啟動(dòng)時(shí)初始化onLineCount和maxOnLineCount兩個(gè)變量，
 * 并將其置于服務(wù)器上下文（ServletContext）中，其初始值都是0。
 */
@WebListener
public class InitListener implements ServletContextListener {
    public void contextDestroyed(ServletContextEvent evt) {
    }
    public void contextInitialized(ServletContextEvent evt) {
        evt.getServletContext().setAttribute("onLineCount", 0);
        evt.getServletContext().setAttribute("maxOnLineCount", 0);
    }
}

/**
 * 會(huì)話監(jiān)聽器，在用戶會(huì)話創(chuàng)建和銷毀的時(shí)候根據(jù)情況修改onLineCount和maxOnLineCount的值。
 */
@WebListener
public class MaxCountListener implements HttpSessionListener {
    public void sessionCreated(HttpSessionEvent event) {
        ServletContext ctx = event.getSession().getServletContext();
        int count = Integer.parseInt(ctx.getAttribute("onLineCount").toString());
        count++;
        ctx.setAttribute("onLineCount", count);
        int maxOnLineCount = Integer.parseInt(ctx.getAttribute("maxOnLineCount").toString());
        if (count > maxOnLineCount) {
            ctx.setAttribute("maxOnLineCount", count);
            DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            ctx.setAttribute("date", df.format(new Date()));
        }
    }
    public void sessionDestroyed(HttpSessionEvent event) {
        ServletContext app = event.getSession().getServletContext();
        int count = Integer.parseInt(app.getAttribute("onLineCount").toString());
        count--;
        app.setAttribute("onLineCount", count);
    }
}

@WebServlet(name = "SessionServlet",value = "/sessionCount")
public class SessionServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html");
        //獲取上下文對(duì)象
        ServletContext servletContext = this.getServletContext();
        Integer onLineCount = (Integer) servletContext.getAttribute("onLineCount");
        System.out.println("invoke doGet");
        PrintWriter out = resp.getWriter();
        out.println("<html><body>");
        out.println("<h1>" + onLineCount + "</h1>");
        out.println("</body></html>");
    }
}

public class Event extends ApplicationEvent {
    private static final long serialVersionUID = 1L;
    private String msg ;
    private static final Logger logger=LoggerFactory.getLogger(Event.class);
    public Event(String msg) {
        super(msg);
        this.msg = msg;
        logger.info("add event success! message: {}", msg);
    }
    public String getMsg() {
        return msg;
    }
    public void setMsg(String msg) {
        this.msg = msg;
    }
}

@Component
public class MyListener implements ApplicationListener<Event>{
    private static final Logger logger= LoggerFactory.getLogger(MyListener.class);
    @Override
    public void onApplicationEvent(Event event) {
        logger.info("listener get event,sleep 2 second...");
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        logger.info("event msg is:{}",event.getMsg());
    }
}

@RequestMapping("/notice/{msg}")
    public void notice(@PathVariable String msg){
        logger.info("begin>>>>>");
        applicationEventPublisher.publishEvent(new Event(msg));
        logger.info("end<<<<<<<");
    }