[FIXED] @WebFilter(urlPatterns) not mapping http request properly

Issue

I have a function with @GetMapping(value = "/getToken") that writes json content.

@GetMapping(value = "/getToken")
    public String getToken(HttpServletRequest request, HttpServletResponse response, Model model) {
             // jsonObject
              PrintWriter out = response.getWriter();
                out.print(jsonObject);
}

Now, A user can make a GET Request to above mapping using a url like this:

localhost:8080/getToken?username="username"&password="password"

I have also created a class called CORSFilter that implements javax.servlet.Filter and i want this filter to intercept only those request that have /getToken in the request path.

@WebFilter(urlPatterns = "/getToken")
    public class CORSFilter implements Filter {
     public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
      //validate user and password
            chain.doFilter(requestToUse, responseToUse);
    
    }
}

Now, when I hit localhost:8080 or localhost:8080/thankyou in the browser then the above filter is getting called.

How can I stop this? I want to call above filter only if the url path is localhost:8080/getToken?username="user"&password="pass"

Solution

Unfortunately, Spring Boot doesn't honor the urlPatterns for filters declared with WebFilter. If you need to apply a pattern, you'll have to declare the filter as a bean and declare a filter registration for that bean, in a configuration class. For example:

@Bean
public FilterRegistrationBean<CORSFilter> corsFilterRegistration() {
    FilterRegistrationBean<CORSFilter> filterRegistrationBean =
        new FilterRegistrationBean<>(corsFilter());
    filterRegistrationBean.setUrlPatterns(Collections.singleton("/getToken"));
    return filterRegistrationBean;
}

@Bean
public CORSFilter corsFilter() {
    return new CORSFilter();
}

Note however that Spring Boot has native support for CORS. You don't need any filter for that.

Answered By - JB Nizet
Answer Checked By - Cary Denson (JavaFixing Admin)