在Spring拦截器中设置自定义响应

Question

Here is my interceptor method where i want to set custom response to tell the UI what happened

@Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
                throws Exception {
    HttpSession session = request.getSession(false);
    if (session != null) 
         return true;
        else{
        response.sendError(HttpServletResponse.SC_REQUEST_TIMEOUT)
        return false;
        }
    }

And in web.xml

<error-page>
    <error-code>408</error-code>
    <location>/error.html</location>
</error-page>

spring-servlet.xml

<mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/**" />
            <mvc:exclude-mapping path="/login" />
            <bean class="com.example.CustomInterceptor" />
        </mvc:interceptor>
    </mvc:interceptors>

When the session is timed out its not sending any response after return false. Even the below is not working

response.sendRedirect("http://localhost:8080/home");

Answer 1

You can try very simple thing. Change your mvc:interceptros structure to

<mvc:interceptors>
     <bean class="com.example.CustomInterceptor" />
</mvc:interceptors>

This essentially mean apply the interceptor to all applicable requests. I will come in a moment to why I say applicable in a moment. If above works then the issue is with your mapping.

Now as you know interceptors are configured at the level of HandlerMapping and it will be RequestMappingHandlerMapping (Spring 3.1+ with mvc:annotation-driven ) or DefaultAnnotationHandlerMapping in your case.

Now as you have use <mvc:mapping path="/**" /> will map to all requests (including subpaths) as long as they are valid mappings . So lets say you have controller

@RequestMapping(value="/home", method = RequestMethod.GET)
public String welcome() {
    return "welcome";
}

you cannot hit http://localhost:8080/yourProjectName/home/test and expect it to hit the interceptor. So you have to hit http://localhost:8080/yourProjectName/home as that is a valid HandlerMapping.

As to to response first debug if your interceptor is getting hit for any requests. If it does work then

response.sendError(HttpServletResponse.SC_REQUEST_TIMEOUT);

should redirect you to error.html as you have used

<error-page>
    <error-code>408</error-code>
    <location>/error.html</location>
</error-page>