Spring Boot add if statement in every action in controller

Question

I need to redirect every action in the controller depending on some condition from the service.

Example:

@RestController
public class MyController{

    @Autowired
    private MyService myService;

    @GetMapping("/action1")
    public String action1() {
        if(myService.checkIfError()) {
            return "redirect:/error";
        } else {
            // specific code of action1
        }
    }

    @GetMapping("/action2")
    public String action2() {
        if(myService.checkIfError()) {
            return "redirect:/error";
        } else {
            // specific code of action2
        }
    }
}

In code above both action1 and action2 have some specific code, but part of code if(myService.checkIfError())return "redirect:/error";} is same to all actions.

Can someone tell me how to remove this boilerplate code so that code specific to actions remains?

Answer 1

You can use a filter for this:

@Component
public class YourFilter implements Filter {

    @Autowired
    private MyService myService;

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
            throws IOException, ServletException {

        HttpServletResponse httpServletResponse = (HttpServletResponse) servletResponse;

        if (myService.checkIfError()) {
            httpServletResponse.sendRedirect("/error");
            return;
        }

        filterChain.doFilter(servletRequest, servletResponse);
    }
}

Spring Boot will autowire this filter, and it will intercept all requests.