404 error in Spring (java config / no web.xml)

Question

Trying to provide a custom 404 error page in a web application that, to the best of my knowledge, uses Java Config (thus no web.xml).

We have the following versions of the related libraries: spring ("5.1.2.RELEASE"), spring-security ("5.1.1.RELEASE").

Disclaimer

I have checked different approaches here in StackOverflow. Please don't suggest results for web.xml, Thymeleaf or Spring Boot. This is not applicable.

Among others; I tried with the following approaches:

• @Controller annotation ( here and here )
• adding a web.xml

None produced the expected result (that is, still getting the default webserver layout and error).

Controller annotation approach

• exception package

  package ...; import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.ControllerAdvice; import org.springframework.web.bind.annotation.ExceptionHandler; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.ResponseBody; import org.springframework.web.servlet.NoHandlerFoundException; @ControllerAdvice public class GlobalExceptionHandler { // Option A (used as an alternative to option B) //@ExceptionHandler(Exception.class) //public String handle(Exception ex) { // return "redirect:/404"; //} @RequestMapping(value = {"/404"}, method = RequestMethod.GET) public String NotFoundPage() { return "404"; } // Option B (used as an alternative to option A) @ExceptionHandler(Exception.class) public ResponseEntity<String> handleNoHandlerFoundException(GlobalExceptionHandler ex) { ResponseEntity responseEntity = new ResponseEntity<>(new RestClientException("Testing exception"), HttpStatus.NOT_FOUND); return responseEntity; } }

• init class

  package ...; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.PropertySource; import org.springframework.transaction.annotation.EnableTransactionManagement; import org.springframework.web.servlet.config.annotation.EnableWebMvc; import org.springframework.web.servlet.config.annotation.ViewControllerRegistry; import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter; import org.springframework.web.bind.annotation.ExceptionHandler; import org.springframework.http.ResponseEntity; import org.springframework.http.HttpStatus; import org.springframework.web.servlet.NoHandlerFoundException; import org.springframework.web.servlet.config.annotation.ViewControllerRegistry; @Configuration @ComponentScan("...") @EnableWebMvc @EnableTransactionManagement @PropertySource("classpath:application.properties") public class WebAppConfig extends WebMvcConfigurerAdapter { @ExceptionHandler({ Exception.class }) public ResponseEntity<RestClientException> handle(NoHandlerFoundException e) { return new ResponseEntity<>(new RestClientException("Testing exception"), HttpStatus.NOT_FOUND); } ... @Override public void addViewControllers(ViewControllerRegistry registry) { super.addViewControllers(registry); registry.addViewController("/404.jsp").setViewName("404"); } }

There is also an Initializer class ( public class Initializer implements WebApplicationInitializer ), which seems to conflict with some suggested options (defined here and here ); so the webapp-init class is not modified.

web.xml approach

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="ROOT" xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    version="2.4">

<error-page>
  <error-code>404</error-code>
  <location>/error</location>
</error-page>
<error-page>
    <exception-type>java.lang.Exception</exception-type>
    <location>/error</location>
</error-page>

</web-app>

The 404.jsp or 404.html files are placed (currently for testing purposes at all the following locations):

    src/main/resources
    ├── ...
    ├── error
    │   └── 404.html
    ├── public
    │   ├── 404.html
    │   └── error
    │       └── 404.html
    ├── templates
    │   └── 404.html
    └── ...

    src/main/webapp/WEB-INF/
    ├── error.jsp
    ├── tags
    │   └── ...
    └── views
        ├── 404.html
        ├── 404.jsp
        ├── error.jsp
        └── ...

Any idea on what is missing or wrong?

Answer 1

Although not as clear as I would like, this is a sort of working version to at least provide some customisation to error pages. It is a first approach but hopefully can help others.

The list of handled exceptions is not extensive, but mainly addressing 404 errors ( NoHandlerFoundException ) and other typical errors like InternalServerErrorException and NullPointerException , to try to catch them all in the end with a generic error for everything else that is an Exception ).

Note that this is not covering other exceptions related to eg bad syntax in a JSTL template ( org.apache.jasper.* ; exceptions that cannot apparently be caught here).

These are the related changes and additions to the source base:

CustomSimpleMappingExceptionResolver.java (provide generic exceptions, yet logs details)

package ...;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import javax.ws.rs.InternalServerErrorException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.http.HttpStatus;
import org.springframework.web.servlet.handler.SimpleMappingExceptionResolver;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.NoHandlerFoundException;

public class CustomSimpleMappingExceptionResolver extends SimpleMappingExceptionResolver {

    public CustomSimpleMappingExceptionResolver() {
        // Turn logging on by default
        setWarnLogCategory(getClass().getName());
    }

    @Override
    public String buildLogMessage(Exception e, HttpServletRequest req) {
        return "MVC exception: " + e.getLocalizedMessage();
    }

    @Override
    protected ModelAndView doResolveException(HttpServletRequest request, HttpServletResponse response,
                                              Object handler, Exception ex) {

        // Log exception
        ex.printStackTrace();
        String exceptionCause = ex.toString();
        String exceptionType = ex.getClass().getCanonicalName();

        // Get the ModelAndView to use
        ModelAndView mav = super.doResolveException(request, response, handler, ex);

        // Make more information available to the view - note that SimpleMappingExceptionResolver adds the exception already
        mav.addObject("url", request.getRequestURL());
        mav.addObject("timestamp", new Date());

        ArrayList<String> exceptions404 = new ArrayList<String>(
                Arrays.asList(
                        NoHandlerFoundException.class.getName()
                        )
        );
        ArrayList<String> exceptions500 = new ArrayList<String>(
                Arrays.asList(
                        InternalServerErrorException.class.getName(),
                        NullPointerException.class.getName()
                        )
        );

        String userExceptionDetail = ex.toString();
        String errorHuman = "";
        String errorTech = "";

        if (exceptions404.contains(exceptionType)) {
            errorHuman = "We cannot find the page you are looking for";
            errorTech = "Page not found";
            userExceptionDetail = String.format("The page %s cannot be found", request.getRequestURL());
            mav.setViewName("/error/404");
            mav.addObject("status", HttpStatus.NOT_FOUND.value());
        } else if (exceptions500.contains(exceptionType)) {
            errorHuman = "We cannot currently serve the page you request";
            errorTech = "Internal error";
            userExceptionDetail = "The current page refuses to load due to an internal error";
            mav.setViewName("/error/500");
            mav.addObject("status", HttpStatus.INTERNAL_SERVER_ERROR.value());
        } else {
            errorHuman = "We cannot serve the current page";
            errorTech = "General error";
            userExceptionDetail = "A generic error prevents from serving the page";
            mav.setViewName("/error/generic");
            mav.addObject("status", response.getStatus());
        }

        Exception userException = new Exception(userExceptionDetail);
        mav.addObject("error_human", errorHuman);
        mav.addObject("error_tech", errorTech);
        mav.addObject("exception", userException);
        return mav;
    }
}

WebAppConfig.java (registers custom exception resolver as an exception handler)

package ...;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.annotation.Scope;
import org.springframework.context.annotation.ScopedProxyMode;
import org.springframework.core.env.Environment;
import org.springframework.core.Ordered;
import org.springframework.http.HttpStatus;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.NoHandlerFoundException;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

import java.lang.ClassNotFoundException;
import java.lang.NullPointerException;
import javax.annotation.Resource;
import javax.ws.rs.InternalServerErrorException;
import java.util.Properties;

@Configuration
@ComponentScan("...")
@EnableWebMvc
@EnableTransactionManagement
@PropertySource("classpath:application.properties")
public class WebAppConfig extends WebMvcConfigurerAdapter {

    @Resource
    private Environment env;

    // ...

    @Bean
    HandlerExceptionResolver customExceptionResolver () {
        CustomSimpleMappingExceptionResolver resolver = new CustomSimpleMappingExceptionResolver();
        Properties mappings = new Properties();
        // Mapping Spring internal error NoHandlerFoundException to a view name
        mappings.setProperty(NoHandlerFoundException.class.getName(), "/error/404");
        mappings.setProperty(InternalServerErrorException.class.getName(), "/error/500");
        mappings.setProperty(NullPointerException.class.getName(), "/error/500");
        mappings.setProperty(ClassNotFoundException.class.getName(), "/error/500");
        mappings.setProperty(Exception.class.getName(), "/error/generic");
        resolver.setExceptionMappings(mappings);
        // Set specific HTTP codes
        resolver.addStatusCode("404", HttpStatus.NOT_FOUND.value());
        resolver.addStatusCode("500", HttpStatus.INTERNAL_SERVER_ERROR.value());
        resolver.setDefaultErrorView("/error/generic");
        resolver.setDefaultStatusCode(200);
        // This resolver will be processed before the default ones
        resolver.setOrder(Ordered.HIGHEST_PRECEDENCE);
        resolver.setExceptionAttribute("exception");
        return resolver;
    }

    // ...

    @Bean
    public InternalResourceViewResolver setupViewResolver() {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views");
        resolver.setSuffix(".jsp");
        resolver.setExposeContextBeansAsAttributes(true);
        return resolver;
    }

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        super.addViewControllers(registry);
    }
}

Initializer.java (adding dispatcherServlet.setThrowExceptionIfNoHandlerFound(true); ; maybe not needed)

package ...;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.ContextLoaderListener;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;

public class Initializer implements WebApplicationInitializer {

    public void onStartup(ServletContext servletContext) throws ServletException {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(WebAppConfig.class);
        servletContext.addListener(new ContextLoaderListener(ctx));
        ctx.setServletContext(servletContext);
        DispatcherServlet dispatcherServlet = new DispatcherServlet(ctx);
        dispatcherServlet.setThrowExceptionIfNoHandlerFound(true);

        // Add the dispatcher servlet mapping manually and make it initialize automatically
        ServletRegistration.Dynamic servlet = servletContext.addServlet("dispatcher", dispatcherServlet);
        servlet.addMapping("/");
        servlet.addMapping("*.png");
        servlet.addMapping("*.jpg");
        servlet.addMapping("*.css");
        servlet.addMapping("*.js");
        servlet.addMapping("*.txt");
        servlet.setLoadOnStartup(1);

        // ...

    }
}

Structure of views and tags related to error classes:

    src/main/webapp/WEB-INF/
    ├── tags
    │   └── error.tag
    └── views
        ├── error
        │   ├── 404.jsp
        │   ├── 500.jsp
        └────── generic.jsp

src/main/webapp/WEB-INF/tags/error.tag

<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<!DOCTYPE html>
<head>
    <title>Error page</title>
</head>
<body>
<div class="container">
    <h3><c:out value="${error_human}" /></h3>

    <p><br/><br/></p>

    <div class="panel panel-primary">
        <div class="panel-heading">
            <c:out value="${error_tech}" />
        </div>
        <div class="panel-body">
            <p><c:out value="${exception_message}" /></p>
        </div>
    </div>
</div>
</body>
</html>

src/main/webapp/WEB-INF/views/error/404.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"
         pageEncoding="utf-8" isErrorPage="true" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib tagdir="/WEB-INF/tags/" prefix="g" %>

<c:set var = "error_human" scope = "session" value = "We cannot find the page you are looking for"/>
<c:set var = "error_tech" scope = "session" value = "Page not found"/>
<c:set var = "exception_message" scope = "session" value = "The current page cannot be found"/>
<g:error />

src/main/webapp/WEB-INF/views/error/500.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"
         pageEncoding="utf-8" isErrorPage="true" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib tagdir="/WEB-INF/tags/" prefix="g" %>

<c:set var = "error_human" scope = "session" value = "We cannot currently serve the page you request"/>
<c:set var = "error_tech" scope = "session" value = "Internal error"/>
<c:set var = "exception_message" scope = "session" value = "The current page refuses to load due to an internal error"/>
<g:error />

src/main/webapp/WEB-INF/views/error/generic.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"
         pageEncoding="utf-8" isErrorPage="true" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib tagdir="/WEB-INF/tags/" prefix="g" %>

<c:set var = "error_human" scope = "session" value = "We cannot serve the current page"/>
<c:set var = "error_tech" scope = "session" value = "General error"/>
<c:set var = "exception_message" scope = "session" value = "A generic error prevents from serving the page"/>
<g:error />

Answer 2

Reading the Spring Boot docs, this works for me:

  @Bean
   public ErrorPageRegistrar errorPageRegistrar() {
     return registry -> registry.addErrorPages(new ErrorPage(HttpStatus.NOT_FOUND, "/index.html"));  }

This is equivalente to web.xml.

Answer 3

Make sure you can access 404 page, and then add these codes.

@ControllerAdvice
public class GlobalExceptionHandler {

    @ResponseStatus(HttpStatus.NOT_FOUND)
    @ExceptionHandler(NoHandlerFoundException.class)
    public String handle404(Model model, HttpServletRequest req, Exception ex) {
        return "/404";
    }
}

application.yaml

spring:
  mvc:
    throwExceptionIfNoHandlerFound: true # if page not found, it will throw error, and then ControllerAdvice will catch the error.

PS: springBoot version=2.4.2; Java=15