为什么全局异常处理无法捕获Filter过滤器中抛出的异常？

• @RestControllerAdvice 是Spring MVC提供的全局异常处理组件，生效范围仅限Spring Controller层抛出的异常。Filter属于Servlet层级的组件，执行顺序在DispatcherServlet之前，异常抛出时请求还未进入Spring MVC的处理链路，自然无法被Spring的全局异常处理器捕获。
• Filter抛出的异常默认会被Tomcat、Undertow等Servlet容器直接接收，容器会直接走内置的错误页跳转逻辑，不会将异常传递到Spring的处理流程中。

方案1：Filter内自行捕获异常写回响应 #

直接在doFilter方法外层增加try-catch，捕获异常后按照你期望的返回格式直接写入响应，和你全局异常处理的逻辑保持一致即可，示例代码：

@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
    HttpServletResponse httpServletResponse = (HttpServletResponse) servletResponse;
    try {
        String token = httpServletRequest.getHeader("token");
        if (token == null)
            throw new NoTokenException();

        String s = jwtToken.parseJwt(token);
        httpServletRequest.setAttribute("id", s);

        filterChain.doFilter(servletRequest, servletResponse);
    } catch (Exception e) {
        httpServletResponse.setContentType("application/json;charset=UTF-8");
        httpServletResponse.getWriter().write("msg");
        httpServletResponse.flushBuffer();
    }
}

方案2：转发异常到Spring错误处理端点 #

捕获异常后将请求转发到Spring Boot默认的错误处理路径/error，异常就会进入Spring的处理链路，你现有的全局异常处理器也可以正常捕获处理：

// 放在Filter的catch块中
catch (Exception e) {
    httpServletRequest.setAttribute("javax.servlet.error.exception", e);
    httpServletRequest.getRequestDispatcher("/error").forward(httpServletRequest, httpServletResponse);
}

内容的提问来源于stack exchange，提问作者user16836342