Springboot-17原生组件注入（servlet、fileter、listener）

Springboot-17原生组件注入（servlet、fileter、listener） 1、方式一：使用Servlet API

//指定扫描目录
@ServletComponentScan(basePackages = "com.atguigu.admin") :指定原生Servlet组件都放在那里
//servelt
@WebServlet(urlPatterns = "/my")：效果：直接响应，没有经过Spring的拦截器？
//过滤器
@WebFilter(urlPatterns={"/css/*","/images/*"})
//监听器
@WebListener

• servlet

package com.springbootweb.Servelt;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

//说明这是一个servlet,url为路径
@WebServlet(urlPatterns = "/servlet")
public class MySelvert extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().write("123456");
    }
}

• fileter

package com.springbootweb.Servelt;

import lombok.extern.slf4j.Slf4j;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

//过滤路径
@WebFilter(urlPatterns = {"/my","/yan/*"})
@Slf4j
public class MyFileter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        log.info("初始化");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.info("开始工作");
        filterChain.doFilter(servletRequest,servletResponse);
    }

    @Override
    public void destroy() {
        log.info("销毁");
    }
}

• listener

package com.springbootweb.Servelt;

import lombok.extern.slf4j.Slf4j;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

@Slf4j
@WebListener
public class MyListener implements ServletContextListener {

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        ServletContextListener.super.contextDestroyed(sce);
    }

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        ServletContextListener.super.contextInitialized(sce);
    }
}

2、方式二：使用RegistrationBean

去掉以上三个组件注解单独Config注入

代码如下：

package com.springbootweb.Servelt;

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 org.springframework.context.annotation.Configuration;

import java.util.Arrays;

@Configuration
public class MyRegistConfig {

    @Bean
    public ServletRegistrationBean myServlet(){
        MySelvert myServlet = new MySelvert();

        return new ServletRegistrationBean(myServlet,"/my","/my02");
    }


    @Bean
    public FilterRegistrationBean myFilter(){

        MyFileter myFilter = new MyFileter();
//        return new FilterRegistrationBean(myFilter,myServlet());
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(myFilter);
        filterRegistrationBean.setUrlPatterns(Arrays.asList("/my","/css/*"));
        return filterRegistrationBean;
    }

    @Bean
    public ServletListenerRegistrationBean myListener(){
        MyListener mySwervletContextListener = new MyListener();
        return new ServletListenerRegistrationBean(mySwervletContextListener);
    }
}

3、拓展

• 3.1 @ServletComponentScan("com.springbootweb.Servelt")如果不指定路径，默认扫描启动类之下包的文件；

• 3.2 多个Servlet都能处理到同一层路径，精确优选原则；
  A： /my/
  B： /my/1

• 3.3 DispatchServlet 如何注册进来
  1、容器中自动配置了 DispatcherServlet 属性绑定到 WebMvcProperties；对应的配置文件配置项是 spring.mvc。
  2、通过 ServletRegistrationBean 把 DispatcherServlet 配置进来。
  3、 默认映射的是 / 路径。