SpringBoot中对拦截器和过滤器的理解

1、两者的关系

2、过滤器的使用步骤

　　实现Filter接口，并加上@WebFilter注解

@Slf4j
// filterName 为该过滤器的名称；
// urlPatterns 对哪些url进行拦截
@WebFilter(filterName = "loginCheckFilter", urlPatterns = "/*")
public class LoginCheckFilter implements Filter {
    // 路径匹配器
    public static final AntPathMatcher antPathMatcher = new AntPathMatcher();

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
        HttpServletResponse httpServletResponse = (HttpServletResponse) servletResponse;

        String requestURI = httpServletRequest.getRequestURI();

        log.info("拦截到请求: {}", requestURI);

        // 定义不需要拦截的url
        String[] urls = new String[]{
                // 匹配目录
                "/backend/page/**",
        };

        boolean check = check(urls, requestURI);
        if (check){
            log.info("本次拦截{}不需要处理", requestURI);
　　　　　　　　//通过filterChain.doFilter来放行请求

            filterChain.doFilter(httpServletRequest, httpServletResponse);
            return;
        }
　　　　　// 向页面返回相应数据
//        httpServletResponse.getWriter().write(JSON.toJSONString(Result.error("NOLOGIN")));
　　　　　// 重定向
        httpServletResponse.sendRedirect("/backend/page/login/login.html");
    }

    public boolean check(String[] urls, String requestURL){
        for (String url : urls) {
            boolean match = antPathMatcher.match(url, requestURL);
            if(match){
                return true;
            }
        }
        return false;
    }
}

 　　在启动类上加上@ServletComponentScan

@Slf4j
@ServletComponentScan
@SpringBootApplication
public class ReggieApplication {
    public static void main(String[] args) {
        SpringApplication.run(ReggieApplication.class, args);
    }
}

3、拦截器的使用步骤

　　实现HandlerInterceptor接口

public class MyInterceptor implements HandlerInterceptor {
    // 在目标方法执行之前执行
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle is running");
        // false 阻止；true 放行
        return true;
//        return HandlerInterceptor.super.preHandle(request, response, handler);
    }
    // 在目标方法执行之后，视图对象返回之前执行
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle is running");
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }
    // 在流程都执行完毕后执行
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion is running");
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

　　注册该拦截器

@Configuration
public class InterceptorConfigurer implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // 自己定义的拦截器
        MyInterceptor myInterceptor = new MyInterceptor();
        // 对所有目标方法都执行拦截操作
        // addPathPatterns表示黑名单，excludePathPatterns表示白名单
        registry.addInterceptor(myInterceptor).addPathPatterns("/**");
    }
}