#Value variable is null in customFilter implementing Filter - spring-boot

Question

my custom filter is not taking value from .properties/.yml file
Note: property file is located at src/main/resources folder
#Slf4j
public class CustomFilter implements Filter {
#Value("${xyz.domainName:http://localhost:8080/x1}")
private String DOMAIN_NAME;
private static final String REDIRECT_URL_ENDPOINT = "/v1/xyz/abc/";
#Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
String url = request.getRequestURL().toString();
String id = url.substring(url.lastIndexOf("/") + 1);
if (url.startsWith(DOMAIN_NAME)) {
ServletContext context = request.getServletContext();
RequestDispatcher dispatcher = context.getRequestDispatcher(REDIRECT_URL_ENDPOINT + id);
dispatcher.forward(request, response);
}
else
filterChain.doFilter(request, response);
}
}
Edit (Added WebSecurityConfigClass): My WebSecurityConfig class looks like:
#EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
#Override
protected void configure(HttpSecurity http) throws Exception {
http.addFilterBefore(new CustomFilter(), ApiKeyAuthFilter.class);
}
}

Answer 1

Looking at the code, you filter is not managed by the Spring Context, therefore Spring-related functionalities like #Value do not work. So, let Spring take care of your filter.
#Component
#Slf4j
public class CustomFilter implements Filter {
#Value("${xyz.domainName:http://localhost:8080/x1}")
private String DOMAIN_NAME;
private static final String REDIRECT_URL_ENDPOINT = "/v1/xyz/abc/";
#Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
String url = request.getRequestURL().toString();
String id = url.substring(url.lastIndexOf("/") + 1);
if (url.startsWith(DOMAIN_NAME)) {
ServletContext context = request.getServletContext();
RequestDispatcher dispatcher = context.getRequestDispatcher(REDIRECT_URL_ENDPOINT + id);
dispatcher.forward(request, response);
}
else
filterChain.doFilter(request, response);
}
#Bean
public FilterRegistrationBean registerFilter() {
FilterRegistrationBean registration = new FilterRegistrationBean();
registration.setFilter(this);
registration.addUrlPatterns("/*");
return registration;
}
}
If you want to register the filter before a Spring security filter you can do this:
#EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
#Autowired
private Customfilter customfilter;
#Override
protected void configure(HttpSecurity http) throws Exception {
http.addFilterBefore(customfilter, ApiKeyAuthFilter.class);
}
}