SpringBoot 注册Servlet三大组件【Servlet、Filter、Listener】-原生代码+@Bean+效果展示

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

package com.szs.springboot04.servlet;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

public class MyServlet extends HttpServlet {

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        doPost(req, resp);

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        resp.getWriter().print("Hello MyServlet!!!");

    }

}

ServletRegistrationBean 注册

@Configuration

public class MyServerConfig {

    /**

     * 注册三大组件

     */

    @Bean

    public ServletRegistrationBean myServlet(){

        ServletRegistrationBean registrationBean =

                new ServletRegistrationBean(new MyServlet(),"/myServlet");

        registrationBean.setLoadOnStartup(1);

        return registrationBean;

    }

效果展示

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2.class MyFilter implements Filter

import javax.servlet.*;

import java.io.IOException;

public class MyFilter implements Filter {

    public MyFilter() {

        super();

    }

    @Override

    public void init(FilterConfig filterConfig) throws ServletException {

        System.out.println("myFilter正在初始化...");

    }

    @Override

    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {

        System.out.println("MyFilter 正在Process...");

        filterChain.doFilter(servletRequest, servletResponse);

    }

    @Override

    public void destroy() {

    }

}

FilterRegistrationBean 注册

@Configuration

public class MyServerConfig {

  @Bean

    public FilterRegistrationBean myFilter(){

        FilterRegistrationBean registrationBean = new FilterRegistrationBean();

        registrationBean.setFilter(new MyFilter());

        registrationBean.setUrlPatterns(Arrays.asList("/hello","/myServlet"));

        return registrationBean;

    }

---

3.class MyListener implements ServletContextListener

public class MyListener implements ServletContextListener {

    @Override

    public void contextInitialized(ServletContextEvent servletContextEvent) {

        System.out.println("contextInitialized ...web应用启动");

    }

    @Override

    public void contextDestroyed(ServletContextEvent servletContextEvent) {

        System.out.println("contextDestroyed... web项目已经销毁");

    }

}

ServletListenerRegistrationBean myListener()

@Configuration

public class MyServerConfig {

@Bean

public ServletListenerRegistrationBean myListener(){

        return  new ServletListenerRegistrationBean<>(new MyListener());

    }