Adding a DispatcherServlet bean does not always override the default

[masrawi]

I do not want boot to handle the / mapping for me. I want it to be handled by the tomcat one. But it seems that boots always handles this. What I used to do with the classic web.xml is define one mapping:

<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>/api/*</url-pattern>
</servlet-mapping>

now I do not see a way to achieve that looking at EmbeddedWebApplicationContext class in the getServletContextInitializerBeans method

[dsyer]

If you are using the autoconfigure features (I assume you are) then you would need to add a bean with id "dispatcherServlet" and have that define the servlet mapping - typically that would mean it was a ServletRegistrationBean with the path mapping you need in it.

I have to ask though: what is the real use case here? Why do you want to change the default mapping?

[masrawi]

Hi,

the use case here is that I am using angularjs and I want it to handle localhost:8080/#/users_list and call GET localhost:8080/api/users (Servlet)

I get an exception if I do the following:

@ComponentScan
@EnableAutoConfiguration
public class SampleApplication
{

    @Bean
    public ServletRegistrationBean dispatcherRegistration()
    {
        ServletRegistrationBean registration = new ServletRegistrationBean(dispatcherServlet());
        registration.addUrlMappings("/api/*");
        return registration;
    }

    @Bean(name = DispatcherServletAutoConfiguration.DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
    public DispatcherServlet dispatcherServlet()
    {
        return new DispatcherServlet();
    }

    public static void main(String[] args)
    {
        SpringApplication app = new SpringApplication(new Object[] { SampleApplication.class });
        app.run(args);
    }

    @Bean
    public ServerProperties creatServerPropertiesBean()
    {
        ServerProperties n = new ServerProperties();
// n.setPort(9000);
        return n;
    }
}
``

Caused by: java.lang.IllegalStateException: Registration is null. Was something already registered for name=[dispatcherServlet]?
at org.springframework.util.Assert.state(Assert.java:385)
at org.springframework.boot.context.embedded.RegistrationBean.configure(RegistrationBean.java:107)
at org.springframework.boot.context.embedded.ServletRegistrationBean.configure(ServletRegistrationBean.java:164)
at org.springframework.boot.context.embedded.ServletRegistrationBean.onStartup(ServletRegistrationBean.java:156)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext$1.onStartup(EmbeddedWebApplicationContext.java:207)
at org.springframework.boot.context.embedded.tomcat.ServletContextInitializerLifecycleListener.lifecycleEvent(ServletContextInitializerLifecycleListener.java:54)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5322)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)

[dsyer]

I'm not really sure I follow yet. Why can't you just use localhost:8080/users? Is the /api/* prefix hardcoded into the client library?

[dsyer]

I looked at this a bit and tried it myself. There is some kind of weird ordering/lifecycle problem if you declare the DispatcherServlet yourself. I will continue to pursue that, but in the meantime you can just inject it, like this:

    @Bean
    public ServletRegistrationBean dispatcherRegistration(DispatcherServlet dispatcherServlet) {
        ServletRegistrationBean registration = new ServletRegistrationBean(
                dispatcherServlet);
        registration.addUrlMappings("/app/*");
        return registration;
    }

(I.e. don't add a @Bean for the DispatcherServlet as well).

[dsyer]

I changed the summary of this issue to "Adding a DispatcherServlet bean does not always override the default" because that's really the problem. It's not super urgent though since there is no need to create a custom DispatcherServlet bean in most cases.

[dsyer]

This works as designed actually - the SampleApplication has to be @Configuration otherwise the dispatcher servlet is created and registered twice.

[tkruse]

We have the same issue, we start our SpringApplication like this

SpringApplicationBuilder applicationBuilder = new SpringApplicationBuilder();
ConfigurableApplicationContext appContext = applicationBuilder.sources(ApplicationConfig.class).run(args);

And declared a ServletRegistrationBean named dispatcherServlet in a

@Bean public ServletRegistrationBean dispatcherServlet() {...}

method in the ApplicationConfig class, which is annotated with @configuration, but the method is never even invoked. This using Spring 4.0.0.RELEASE and Spring Boot 0.5.0.M6. We use your workaround for now.

[dsyer]

Did you try a snapshot? If you did and it still doesn't work can you push a sample project somewhere that we can look at?

[tkruse]

I am not sure what you mean. Do you mean snapshot versions of Spring boot? No, we just use 0.5.0.M6. I'd like to provide sample projects, but I don't habe much time, so it may take several days until I find free time...

[tkruse]

I cannot reproduce using 0.5.0.BUILD-SNAPSHOT