使用Servlet API

官方文档

官方文档 - Servlets, Filters, and listeners
要注意原生的servlet不会进入springboot配置的拦截器里面

配置扫描原生组件

@ServletComponentScan(basePackages = "com")
@SpringBootApplication
public class SpringbootStudy03Application {
    
    

    public static void main(String[] args) {
    
    
        SpringApplication.run(SpringbootStudy03Application.class, args);
    }

}

@ServletComponentScan(basePackages = “com”)这个是配置扫描servlet的包

原生的Servlet

@WebServlet(urlPatterns="/my")
public class MyServlet extends HttpServlet {
    
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    
        resp.getWriter().write("hello_this_is_my_servlet");
    }
}

原生的过滤器

@Slf4j
@WebFilter(urlPatterns={
    
    "/css/*","/images/*"}) //my
public class MyFilter implements Filter {
    
    
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    
    
        log.info("MyFilter初始化完成");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    
    
        log.info("MyFilter工作");
        chain.doFilter(request,response);
    }

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

原生的监听器

@Slf4j
@WebListener
public class MyServletContextListener implements ServletContextListener {
    
    


    @Override
    public void contextInitialized(ServletContextEvent sce) {
    
    
        log.info("MySwervletContextListener监听到项目初始化完成");
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
    
    
        log.info("MySwervletContextListener监听到项目销毁");
    }
}

使用注册的方式

//@Configuration(proxyBeanMethods = true)
@Configuration
public class MyRegistConfig {
    
    
    @Bean
    public ServletRegistrationBean myServlet(){
    
    
        MyServlet myServlet = new MyServlet();

        return new ServletRegistrationBean(myServlet,"/my","/my02");
    }
   @Bean
    public FilterRegistrationBean myFilter(){
    
    

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

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

}

为什么不用@Configuration(proxyBeanMethods = false)?
因为用@Configuration(proxyBeanMethods = false)的话会创建很多不必要的实例

可以监听到

DispatchServlet 如何注册进来?

● 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。
● 通过 ServletRegistrationBean 把 DispatcherServlet 配置进来。
● 默认映射的是 / 路径。

原生的Servlet为什么不会进入Spring流程

Tomcat-Servlet遵循多个Servlet都能处理到同一层路径，精确优选原则
Spring默认处理的是 / 下面的
我们自己配置的是/my
如果我们访问 /my的话他会使用更精确的MyServlet

自己写的servlet和dispatcherservlet是平级的
springmvc底层实际上就是一个大型的servlet, 而他的urlpatterns为 / 。所以当请求/my时会精确匹配到自定义的servlet, 不会经过spring