spring mvc 的配置 及interceptor filter listener servlet 配置

创建 三个类 

分别实现 Filter  ServletContextListener  HttpServlet

在springboot 启动类中@bean加入

2 ，实现 ServletContextIntializer接口 

@SpringBootApplication
public class DemoApplication implements ServletContextInitializer{

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
    
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        servletContext.addServlet("customServlet", new CustomServlet()).addMapping("/root");
        servletContext.addFilter("customfilter", new CustomFilter())
                        .addMappingForServletNames(EnumSet.of(DispatcherType.REQUEST), true, "customServlet");
        servletContext.addListener(new CustomListener());
    }
}

3. 注解方式  主类加上@ServletComponentScan     给三个分别加上注解   

@WebServlet(urlPatterns="/index", name="customServlet")
public class CustomServlet extends HttpServlet{
   ....
}

@WebListener
public class CustomListener implements ServletContextListener{
   ....  
}

@WebFilter(urlPatterns="/*")
public class CustomFilter implements Filter{
  ...  
}

4.   自定义注解 实现  主类上加上此注解

@Target(value = {ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(value = {FirstFilterConfiguration.class})
public @interface EnableFirstFilter {

}

注册配置的bean（

FirstFilterConfiguration.class

）

public class FirstFilterConfiguration {

    public static final Integer ORDER = Integer.MIN_VALUE;    
    
    @Bean
    public FilterRegistrationBean firstFilter(){
　　// 默认不需要的但是为了拦截过滤固定的页面
        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setFilter(new FirstFilter());
        registration.addUrlPatterns("/*");
        registration.setName("firstFilter");
        registration.setOrder(ORDER);
        return registration;
    }
}

public class FirstFilter implements Filter {

    @Override
    public void destroy() {
        
    }

    @Override
    public void doFilter(ServletRequest srst, ServletResponse srsp, FilterChain chain)
            throws IOException, ServletException {
        chain.doFilter(srst, srsp);
    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        
    }

}

@Configuration
@EnableWebMvc
public class WebMvcConfig extends WebMvcConfigurerAdapter{

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        //addResourceHandler  对外暴露的路径       addResourceLocations 对内暴露路径
        registry.addResourceHandler("/aaserts/**").addResourceLocations("classpath:/assets/");
    }
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/ws").setViewName("/ws");
         registry.addViewController("/login").setViewName("/login");
         registry.addViewController("/chat").setViewName("/chat");
    }
    
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(demoInterceptor());
    }
    
    @Bean
    public DemoInterceptor demoInterceptor() {
        return new DemoInterceptor();
    }
    
    //自定义拦截器
    public class DemoInterceptor extends HandlerInterceptorAdapter{
        
        @Override //请求发生前执行
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
                throws Exception {
            return true;
        }
        
        @Override  // 请求发生后执行
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
                ModelAndView modelAndView) throws Exception {
            super.postHandle(request, response, handler, modelAndView);
        }
    }
}

 拦截器