SpringBoot 注册Servlet三大组件【Servlet、Filter、Listener】

由于SpringBoot默认是以jar包的方式启动嵌入式的Servlet容器来启动SpringBoot的web应用，没有web.xml文件。 注册三大组件,class MyServlet()/class MyListener/ class MyFilter 需要自己亲自编写!!

1. class MyServlet

1package com.szs.springboot04.servlet;
2
3import javax.servlet.ServletException;
4import javax.servlet.http.HttpServlet;
5import javax.servlet.http.HttpServletRequest;
6import javax.servlet.http.HttpServletResponse;
7import java.io.IOException;
8
9public class MyServlet extends HttpServlet {
10
11    @Override
12    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
13        doPost(req, resp);
14    }
15
16    @Override
17    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
18        resp.getWriter().print("Hello MyServlet!!!");
19    }
20}

ServletRegistrationBean 注册

1@Configuration
2public class MyServerConfig {
3    /**
4     * 注册三大组件
5     */
6    @Bean
7    public ServletRegistrationBean myServlet(){
8        ServletRegistrationBean registrationBean =
9                new ServletRegistrationBean(new MyServlet(),"/myServlet");
10        registrationBean.setLoadOnStartup(1);
11        return registrationBean;
12    }

效果展示

2.class MyFilter implements Filter

1import javax.servlet.*;
2import java.io.IOException;
3
4public class MyFilter implements Filter {
5    public MyFilter() {
6        super();
7    }
8
9    @Override
10    public void init(FilterConfig filterConfig) throws ServletException {
11        System.out.println("myFilter正在初始化...");
12    }
13
14    @Override
15    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
16        System.out.println("MyFilter 正在Process...");
17        filterChain.doFilter(servletRequest, servletResponse);
18    }
19
20    @Override
21    public void destroy() {
22
23    }
24}

FilterRegistrationBean 注册

1@Configuration
2public class MyServerConfig {
3  @Bean
4    public FilterRegistrationBean myFilter(){
5        FilterRegistrationBean registrationBean = new FilterRegistrationBean();
6        registrationBean.setFilter(new MyFilter());
7        registrationBean.setUrlPatterns(Arrays.asList("/hello","/myServlet"));
8        return registrationBean;
9    }

3.class MyListener implements ServletContextListener

1public class MyListener implements ServletContextListener {
2    @Override
3    public void contextInitialized(ServletContextEvent servletContextEvent) {
4        System.out.println("contextInitialized ...web应用启动");
5    }
6
7    @Override
8    public void contextDestroyed(ServletContextEvent servletContextEvent) {
9        System.out.println("contextDestroyed... web项目已经销毁");
10    }
11}

ServletListenerRegistrationBean myListener()

1@Configuration
2public class MyServerConfig {
3@Bean
4public ServletListenerRegistrationBean myListener(){
5        return  new ServletListenerRegistrationBean<>(new MyListener());
6    }
7