public interface Filter {
    //初始化方法，整個(gè)生命周期中只執(zhí)行一次。
    //在init方法成功(失敗如拋異常等)執(zhí)行完前，不能提供過濾服務(wù)。
    //參數(shù)FilterConfig用于獲取初始化參數(shù)
    public void init(FilterConfig filterConfig) throws ServletException;
 
    //執(zhí)行過濾任務(wù)的方法，參數(shù)FilterChain表示過濾器鏈，doFilter方法中只有執(zhí)行chain.doFilter()后才能調(diào)用下一個(gè)過濾器的doFilter方法
    //才能將請求交經(jīng)下一個(gè)Filter或Servlet執(zhí)行
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException;
 
    //銷毀方法，當(dāng)移出服務(wù)時(shí)由web容器調(diào)用。整個(gè)生命周期中destroy方法只會執(zhí)行一次
    //destroy方法可用于釋放持有的資源，如內(nèi)存、文件句柄等
    public void destroy();
}

public class LoginFilter implements Filter {
    @Override
    public void destroy() {
        System.out.println("filter destroy method");
    }
    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain filterChain)
            throws IOException, ServletException {
        System.out.println("filter doFilter method ");
        // 繼續(xù)傳遞下去
        filterChain.doFilter(arg0,arg1);
    }
    @Override
    public void init(FilterConfig arg0) throws ServletException {
        System.out.println("filter init method");
    }
}

@Configuration
public class FilterConfig {
    @Bean
    public FilterRegistrationBean indexFilterRegistration() {
        FilterRegistrationBean registration = new FilterRegistrationBean(new LoginFilter());
        registration.addUrlPatterns("/");
        return registration;
    }
}

@WebFilter(urlPatterns = "/",filterName = "filter1")
@Order(1)
public class LoginFilter implements Filter {
    @Override
    public void destroy() {
        System.out.println("filter destroy method");
    }
 
    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain filterChain)
            throws IOException, ServletException {
        System.out.println("filter doFilter method   1   ");
        filterChain.doFilter(arg0,arg1);
    }
 
    @Override
    public void init(FilterConfig arg0) throws ServletException {
        System.out.println("filter init method");
    }
}

@SpringBootApplication
@ServletComponentScan
public class FilterTestApplication {
    public static void main(String[] args) {
        SpringApplication.run(FilterTestApplication.class, args);
    }
}

@Autowired ServletContext servletContext; servletContext.addFilter()

@Autowired private ServletContext servletContext;

ServletContext servletContext = request.getServletContext();

@Component
public class TestListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println(sce);
    }
}

public class ServletRegistrationBean<T extends Servlet> extends DynamicRegistrationBean<ServletRegistration.Dynamic> {
    private static final String[] DEFAULT_MAPPINGS = new String[]{"/*"};
    private T servlet;
    private Set<String> urlMappings;
    private boolean alwaysMapUrl;
    private int loadOnStartup;
    private MultipartConfigElement multipartConfig;
    ......
    }