（十）SpringBoot之web 应用开发-Servlets, Filters, listeners

一.需求

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、 FilterListene

二、案例

　　2.1　　通过注册 ServletRegistrationBean、 FilterRegistrationBean 和ServletListenerRegistrationBean 获得

package com.shyroke;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;

import util.MyFilter;
import util.MyListener;
import util.MyServlet;

@SpringBootApplication
public class Springboot01Application {
    
    @Bean
    public ServletRegistrationBean servletRegistrationBean() {
        return new ServletRegistrationBean(new MyServlet(), "/servlet");
    }
    
    @Bean
    public FilterRegistrationBean filterRegistrationBean() {
        return new FilterRegistrationBean(new MyFilter(), servletRegistrationBean());
    }
    
    @Bean
    public ServletListenerRegistrationBean<MyListener> listenerRegistrationBean(){
        return new ServletListenerRegistrationBean<MyListener>(new MyListener());
    }
    
    public static void main(String[] args) {
        SpringApplication.run(Springboot01Application.class, args);
    }
}

　　2.2　　MyServlet.java

package util;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MyServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("我是servlet");
        
        resp.getWriter().write("hello world servlet");
    }

    
    
}

　　2.3　　MyFilter.java

package util;

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 MyFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        System.out.println("我是filter");
        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        
    }
    
}

　　2.4　　MyListener.java

package util;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class MyListener implements ServletContextListener{

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("contextInitialized");
        
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("contextDestroyed");
        
    }

}

　　2.5　　结果

说明servlet生效

filter和listener生效