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目录SpringBoot使用过滤器、拦截器和监听器一、springBoot使用过滤器Spring Boot过滤器的使用(两种方式)方式一:方式二:二、SpringBoot使用拦截器三
两种方式的本质都是一样的,都是去FilterRegistrationBean注册自定义Filter
第一步:先定义Filter。
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 处理request 或response
System.out.println("filter1");
// 调用filter链中的下一个filter
filterChain.doFilter(servletRequest,servletResponse);
}
@Override
public void destroy() {
}
}
第二步:注册自定义Filter
@Configuration
public class FilterConfig {
@Bean
public FilterRegistrationBean registrationBean() {
FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(new MyFilter());
filterRegistrationBean.addUrlPatterns("
@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);
}
}
@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);
}
}
新建一个servlet处理
@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");
//获取上下文对象
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>");
}
}
定义事件类 Event
创建一个类,继承ApplicationEvent,并重写构造函数。ApplicationEvent是Spring提供的所有应用程序事件扩展类。
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;
}
}
创建一个用于监听指定事件的类,需要实现ApplicationListener接口,说明它是一个应用程序事件的监听类。注意这里需要加上@Component注解,将其注入Spring容器中。
@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());
}
}
事件发布
事件发布很简单,只需要使用Spring 提供的ApplicationEventPublisher来发布自定义事件
@Autowired 注入ApplicationEventPublisher
@RequestMapping("/notice/{msg}")
public void notice(@PathVariable String msg){
logger.info("begin>>>>>");
applicationEventPublisher.publishEvent(new Event(msg));
logger.info("end<<<<<<<");
}
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