spring boot整合web

1.springboot与servlet的整合
（1）注意，servlet一定要在启动类的包下或者所在包的子包下，才能被扫描到。
servlet类，name是本类的名字，urlpattents是url栏上的地址。

@WebServlet(name = "FirstServlet",urlPatterns = "/first")
public class FirstServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        resp.getWriter().write("我是你写的第一个sprubgboot与servlet的整合");
    }
}

在启动类只需要添加@ServletComponentScan注解即可
（2）添加bean的形式不使用@ServletComponentScan注解通过添加@bean的形式

 @Bean
    public ServletRegistrationBean getit(){
        ServletRegistrationBean servletRegistrationBean=new ServletRegistrationBean(new FirstServlet());
        servletRegistrationBean.addUrlMappings("/first");
        return  servletRegistrationBean;
    }

2.springboot与filter的整合，与servlet整合相似，启动类不会变，只需要，编写自己的filter类即可

@WebFilter(filterName="FirstFileter",urlPatterns = "/firstFilter")
public class FirstFileter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        servletResponse.setContentType("text/html;charset=utf-8");
        servletResponse.getWriter().write("filter");
    }

    @Override
    public void destroy() {

    }
}

3.整合监听器：

@WebListener
public class FirstListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("listener init--------");
    }
}