SpringBoot攔截器回傳false顯示跨域問題怎麼解決

專案最近新增了一個ip黑白名單的功能, 發現如果ip過濾的攔截器返回false 後前端會顯示跨域, 嘗試修改MVC配置類別後發現還是不行, 最後在攔截器加了個判斷就可以了

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws IOException {
        // ----------- 加上这个就好了 -----------
        if (!(handler instanceof HandlerMethod)) {
            return true;
        }
    }

  WebMvcConfigurer 設定類別

@Configuration
@RestControllerAdvice
public class WebMvcConfig implements WebMvcConfigurer {
    @Resource
    private IpFilterInterceptor ipFilterInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // IP拦截器
        registry.addInterceptor(ipFilterInterceptor)
                .addPathPatterns("/**")
                .order(5);
    }
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowCredentials(true)
                .allowedOriginPatterns("*")
                .allowedMethods("*")
                .allowedHeaders("*")
                .maxAge(3600);
    }
}

修改前的IP攔截器

@Component
public class IpFilterInterceptor implements HandlerInterceptor {
    /**
     * 是否启用
     */
    private boolean enable;
    /**
     * 是否为白名单
     */
    private boolean isWhiteList;
    /**
     * 过滤器
     */
    private List<String> filters;
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws IOException {
        // 停用
        if (!enable) {
            return true;
        }
        String ip = Servlets.getRemoteAddr(request);
        // 本机不过滤
        if (Const.LOCALHOST_IP_V4.equals(ip)) {
            return true;
        }
        // 过滤
        boolean contains = false;
        for (String filter : filters) {
            if (Strings.isBlank(filter)) {
                continue;
            }
            // 检测
            contains = Utils.checkIpIn(ip, filter);
            if (contains) {
                break;
            }
        }
        // 结果
        boolean pass;
        if (isWhiteList) {
            pass = contains;
        } else {
            pass = !contains;
        }
        // 返回
        if (!pass) {
            response.setContentType(StandardContentType.APPLICATION_JSON);
            Servlets.transfer(response, HttpWrapper.of(ResultCode.IP_BAN).toJsonString().getBytes());
        }
        return pass;
    }
}

修改後的IP攔截器

@Component
public class IpFilterInterceptor implements HandlerInterceptor {
    /**
     * 是否启用
     */
    private boolean enable;
    /**
     * 是否为白名单
     */
    private boolean isWhiteList;
    /**
     * 过滤器
     */
    private List<String> filters;
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws IOException {
        // 停用
        if (!enable) {
            return true;
        }
        // ----------- 加上这个就好了 -----------
        if (!(handler instanceof HandlerMethod)) {
            return true;
        }
        String ip = Servlets.getRemoteAddr(request);
        // 本机不过滤
        if (Const.LOCALHOST_IP_V4.equals(ip)) {
            return true;
        }
        // 过滤
        boolean contains = false;
        for (String filter : filters) {
            if (Strings.isBlank(filter)) {
                continue;
            }
            // 检测
            contains = Utils.checkIpIn(ip, filter);
            if (contains) {
                break;
            }
        }
        // 结果
        boolean pass;
        if (isWhiteList) {
            pass = contains;
        } else {
            pass = !contains;
        }
        // 返回
        if (!pass) {
            response.setContentType(StandardContentType.APPLICATION_JSON);
            Servlets.transfer(response, HttpWrapper.of(ResultCode.IP_BAN).toJsonString().getBytes());
        }
        return pass;
    }
}

最後, 問題的原因是出在了攔截器身上需要在preHandle 中判斷handler 的類型必須是HandlerMethod 的話才能通過

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