一.Web开发使用 Controller 基本上可以完成大部分需求，但是我们还可能会用到 Servlet、 Filter、 Listener等等

二.在spring boot中的三种实现方式

 方法一：通过注册ServletRegistrationBean、 FilterRegistrationBean 和 ServletListenerRegistrationBean 获得控制

servlet类：

package com.demo.example.util.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpServletRequest;public class CustomServlet extends HttpServlet {	/**	 * 	 */	private static final long serialVersionUID = 1L;			@Override	protected void doGet(HttpServletRequest request, HttpServletResponse response)			throws ServletException, IOException {		// TODO Auto-generated method stub		System.out.println("servlet get method");		doPost(request , response);	}		@Override	protected void doPost(HttpServletRequest request, HttpServletResponse response)			throws ServletException, IOException {		// TODO Auto-generated method stub		System.out.println("servlet get method");		response.getWriter().write("Hello world");	}	} filter类：

package com.demo.example.util.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;public class CustonFilter implements Filter {	@Override	public void destroy() {		// TODO Auto-generated method stub		System.out.println("do destroy");	}	@Override	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)			throws IOException, ServletException {		System.out.println("do filter");		chain.doFilter(request, response);	}	@Override	public void init(FilterConfig arg0) throws ServletException {		// TODO Auto-generated method stub		System.out.println("do init");	}}

　Listener类：

package com.demo.example.util.listener;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;public class CustomListener implements ServletContextListener {	@Override	public void contextDestroyed(ServletContextEvent servletContextEvent) {		// TODO Auto-generated method stub		System.out.println("servletContextEvent");	}	@Override	public void contextInitialized(ServletContextEvent servletContextEvent) {		// TODO Auto-generated method stub		System.out.println("servletContextEvent");	}}

　

注册bean（第一种方式）

代码注册：（在SpringBootDemoFilerServletLisApplication类中）

@Bean	public ServletRegistrationBean
      
        servletRegistrationBean() {		return new ServletRegistrationBean
       
        (new CustomServlet(), "/customServlet");	}		@Bean	public FilterRegistrationBean
        
          filterRegistrationBean(){		return new FilterRegistrationBean
         
          (new CustonFilter(),servletRegistrationBean() );	}		@Bean	public ServletListenerRegistrationBean
          
            servletListenerRegistrationBean(){		return new ServletListenerRegistrationBean
           
            (new CustomListener()); }
           
          
         
        
       
      

　第二种代码注册：（类似一）

@SpringBootApplicationpublic class SpringBootDemoFilerServletLisApplication implements ServletContainerInitializer{			@Override	public void onStartup(Set
      
       > arg0, ServletContext servletContext) throws ServletException {		// TODO Auto-generated method stub		servletContext.addServlet("CustomServlet", new CustomServlet()).addMapping("/customServlet");		servletContext.addFilter("CustonFilter", new CustonFilter()).addMappingForServletNames(EnumSet.of(DispatcherType.REQUEST), true, "CustomServlet");		servletContext.addListener(new CustomListener());	}
      

　第三种基于注释：

首先：在 SpringBootDemoFilerServletLisApplication 类中添加

 

在listener

在servlet

在filter (  "/*" 代表过滤全局  )