Requests that should be handled by an additional DispatcherServlet result in a 404 response

[DreamPWJ]

I use the ServletRegistrationBean method to add the servlet prefix '/ API.' uniformly. Version 2.3.1 prompts or does not exist 404, while version 2.3.0 allows normal access to the/API / path

[wilkinsona]

Thanks for the report but I cannot reproduce the behaviour that you have described. The following works as excepted:

package com.example.demo;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
public class Gh22682Application {

	public static void main(String[] args) {
		SpringApplication.run(Gh22682Application.class, args);
	}
	
	@Bean
	public ServletRegistrationBean<ExampleServlet> exampleServletRegistrationBean() {
		ServletRegistrationBean<ExampleServlet> registration = 
				new ServletRegistrationBean<Gh22682Application.ExampleServlet>(new ExampleServlet());
		registration.addUrlMappings("/ping");
		return registration;
	}
	
	@SuppressWarnings("serial")
	static class ExampleServlet extends HttpServlet {

		@Override
		protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
			resp.getWriter().println("pong");
			resp.flushBuffer();
		}
		
	}

}

$ curl localhost:8080/ping
pong

If you would like us to spend some more time investigating, please spend some time providing a complete yet minimal sample that reproduces the problem. You can share it with us by pushing it to a separate repository on GitHub or by zipping it up and attaching it to this issue.

[DreamPWJ]

@Configuration
public class ServletConfig {

    @Resource
    private MultipartConfigElement multipartConfigElement;
    
    @Bean
    public ServletRegistrationBean apiServletBean(WebApplicationContext wac) {
        DispatcherServlet servlet = new DispatcherServlet(wac);
        servlet.setThrowExceptionIfNoHandlerFound(true);
        ServletRegistrationBean bean = new ServletRegistrationBean(servlet);
        bean.setLoadOnStartup(1);
        bean.addUrlMappings("/api/*");
        bean.setMultipartConfig(multipartConfigElement);
        bean.setName("apiServlet");
        return bean;
    }
}

[DreamPWJ]

[wilkinsona]

Thanks, but that doesn't give us enough information to diagnose the problem. For example, I can't tell what handlers are in your application and how they are getting registered with your (additional?) DispatcherServlet. As I said above, if you would like us to spend some more time investigating, please spend some time providing a complete yet minimal sample that reproduces the problem. By complete, I mean something that provides everything that we need to reproduce the problem.

[spring-projects-issues]

If you would like us to look at this issue, please provide the requested information. If the information is not provided within the next 7 days this issue will be closed.

[DreamPWJ]

The above has provided the core code for the replication has not the replication?

[wilkinsona]

Unfortunately not, no. As I said above, it doesn't give us enough information to reproduce the problem. For example, I can't tell what handlers are in your application and how they are getting registered with your (additional?) DispatcherServlet.

[DreamPWJ]

run tomcat？

[wilkinsona]

Sorry, but I'm not sure how running Tomcat will help. Your screenshot shows a request being made to /api/token/base but the code that you have provided thus far has no such mapping. Without knowing how that mapping is configured, it's impossible for us to diagnose why you're getting a 404. Please spend some time providing a complete yet minimal sample that reproduces the problem. You can share it with us by pushing it to a separate repository on GitHub or by zipping it up and attaching it to this issue.

[DreamPWJ]

please check https://github.com/DreamPWJ/spring-boot-bug.git

spring boot2.3.2
curl http://127.0.0.1:8080/api/token/base
{"timestamp":"2020-08-08T00:35:22.506+00:00","status":404,"error":"Not Found","message":"","path":"/api/token/base"}

spirng boot2.3.0
curl http://127.0.0.1:8080/api/token/base
success

[wilkinsona]

Thanks for the sample. I can now see what's happening. This is a regression caused by the changes made for #21499. In your case, there are two dispatcher servlets, one that is mapped to / and one that is mapped to /api/*. The / mapping results in setAlwaysUseFullPath(true) being called on the UrlPathHelper:

spring-boot/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.java

Lines 237 to 241 in 181e3b3

	if (servletUrlMapping.equals("/")) {
	UrlPathHelper urlPathHelper = new UrlPathHelper();
	urlPathHelper.setAlwaysUseFullPath(true);
	configurer.setUrlPathHelper(urlPathHelper);
	}

This then prevents mapping a request to api/token/base to the /token/base endpoint.