The previous article has explained the method of defining servlet . The registration method of filter ( Filter ) and listener ( Listener ) is the same as that of servlet . If you are not clear, you can check the next article ( 20 ): This article will use it directly In the way of @WebFilter and @WebListener , complete a Filter and a Listener ; use annotations
@ServletComponentScan// This is to scan the corresponding Servlet package ;
filter file _
com.kfit.filter.MyFilter.Java
package com.kfit.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
/**
*
* Use annotation annotation filters
* @WebFilter defines a class that implements the javax.servlet.Filter interface as a filter
* The attribute filterName declares the name of the filter , optional
* The attribute urlPatterns specifies the URL patterns to be filtered , and can also be declared using the attribute value . ( Specifying the URL patterns to be filtered is a required attribute )
* @author Angel(QQ:412887952)
* @version v.0.1
*/
@WebFilter(filterName="myFilter",urlPatterns="/*")
publicclass MyFilter implements Filter{
@Override
publicvoid init(FilterConfig config) throws ServletException {
System.out.println("过滤器初始化");
}
@Override
publicvoid doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
System.out.println("执行过滤操作");
chain.doFilter(request, response);
}
@Override
publicvoid destroy() {
System.out.println("过滤器销毁");
}
}
ServletContext监听器（Listener）文件
com.kfit.listener.MyServletContextListener:
package com.kfit.listener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
/**
* 使用@WebListener注解，实现ServletContextListener接口
*
* @author Angel(QQ:412887952)
* @version v.0.1
*/
@WebListener
public class MyServletContextListener implements ServletContextListener {
@Override
public void contextDestroyed(ServletContextEvent arg0) {
System.out.println("ServletContex销毁");
}
@Override
public void contextInitialized(ServletContextEvent arg0) {
System.out.println("ServletContex初始化");
}
}
ServletContext监听器（Listener）文件（HttpSessionListener）
MyHttpSessionListener.java
package com.kfit.listener;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
/**
* 监听Session的创建与销毁
*
*/
@WebListener
publicclassMyHttpSessionListenerimplementsHttpSessionListener {
@Override
publicvoid sessionCreated(HttpSessionEvent se) {
System.out.println("Session 被创建");
}
@Override
publicvoid sessionDestroyed(HttpSessionEvent se) {
System.out.println("ServletContex初始化");
}
}
注意不要忘记在 SpringBootSampleApplication.java 上添加 @ServletComponentScan 注解。
启动的过程中我们会看到输出：
ServletContex初始化
过滤器初始化
服务启动后，随便访问一个页面，会看到输出：
执行过滤操作Session 被创建
Why can't I see the session process: http://zhidao.baidu.com/link?url=EP-wlLvKpo8zI5NaIZrESzCdivq3Xg8VgOWQOvfpSLl3opTgvESerpo4wsG6tOs_dm6cQQMF_kQ6THNjNzr2Nq
As for how to register Filter and Listener by code, please refer to the introduction of key servlets in the previous article . The difference is that you need to use the FilterRegistrationBean and ServletListenerRegistrationBean classes.