SpringBoot中默认内置了Servlet容器，Tomcat。SpringBoot默认是以jar包的方式启动内置的Servlet容器，没有web.xml文件。所以只能通过自定义servlet配置。使用ServletRegistrationBean、FilterRegistrationBean、ServletListenerRegistrationBean来实现servle的三大组件。

CustomServletConfig

@Configuration
public class CustomServletConfig {//注册servlet@Beanpublic ServletRegistrationBean myServlet(){ServletRegistrationBean<Myservlet> registrationBean = new ServletRegistrationBean<>();registrationBean.setServlet(new Myservlet());registrationBean.addUrlMappings("/myServlet");return  registrationBean;}//注册Filter@Beanpublic FilterRegistrationBean myFilter(){System.out.println("CustomServletConfig.myFilter");FilterRegistrationBean<Filter> registrationBean = new FilterRegistrationBean<>();registrationBean.setFilter(new MyFilter());registrationBean.addUrlPatterns("/showLogin","/test1");return registrationBean;}@Beanpublic ServletListenerRegistrationBean myListener(){ServletListenerRegistrationBean<MyListener> servletListenerRegistrationBean = new ServletListenerRegistrationBean<>();servletListenerRegistrationBean.setListener(new MyListener());return  servletListenerRegistrationBean;}
}

Myservlet

public class Myservlet extends HttpServlet {@Override protected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {System.out.println("Myservlet.doGet");doPost(req,resp);}@Override protected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {System.out.println("Myservlet.doPost");}
}

MyListener

public class MyListener  implements ServletContextListener {@Overridepublic void contextInitialized(ServletContextEvent sce) {System.out.println("MyListener.contextInitialized");}@Overridepublic void contextDestroyed(ServletContextEvent sce) {System.out.println("MyListener.contextDestroyed");}
}

MyFilter

public class MyFilter implements Filter {@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)throws IOException, ServletException {System.out.println("MyFilter.doFilter");filterChain.doFilter(servletRequest,servletResponse);}@Overridepublic void destroy() {}
}

MyListener

public class MyListener  implements ServletContextListener {@Overridepublic void contextInitialized(ServletContextEvent sce) {System.out.println("MyListener.contextInitialized");}@Overridepublic void contextDestroyed(ServletContextEvent sce) {System.out.println("MyListener.contextDestroyed");}
}