Spring using @Value annotation in Filter

Question

I am currently working on a Spring project and I am making a new filter that checks if a valid JWT has been sent in the request.

I am running into an issue where I can't get a value from my application.yml file using the @Value annotation like so.

@Component
@Order(2)
public class JwtConfiguration implements Filter {

    @Value("${jwt.secret}")
    private String jwtSecret;

I know this works fine because I have the same thing in my unit test.

I have read somewhere that the filter is not in the application context so it will not have access to configuration and I will not be able to autowire dependencies.

Does anyone know a good technique for getting values from my application.yml to my filter?

I am also not using any XML configuration and would prefer a solution that doesn't use them.

I am using Spring Boot version 1.3.3.

Answer 1

This can be achieved by implementing ServletContextInitializer. See below sample code.

@Configuration
public class WebConfigurer implements ServletContextInitializer {

    @Value("${jwt.secret}")
    private String jwtSecret;

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        EnumSet<DispatcherType> disps = EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.ASYNC);
        initFilter(servletContext, disps);
    }


    private void initFilter(ServletContext servletContext,
                                              EnumSet<DispatcherType> disps) {
        FilterRegistration.Dynamic myFilter =
            servletContext.addFilter("myFilter",
                new MyFilterClass(jwtSecret));

        // You can pass null as first parameter to below API calls
        myFilter.addMappingForUrlPatterns(disps, true, "/content/*");
        myFilter.addMappingForUrlPatterns(disps, true, "/app/*");
        myFilter.setAsyncSupported(true);
    }

}

Edit/Update:

I suppose there is another way to add filters using Java Config

You can use FilterRegistrationBean to register the filters. Here you can set the order using setOrder method. But think it will create as many ServletContextInitializer as there are filters because FilterRegistrationBean is a ServletContextInitializer See