CORS Angular and SpringBoot - request blocked

Question

I have a problem that I don't seem to figure out. I want to send a http request from my

Angular client:

const url = 'http://localhost:8080/api';
console.log(this.http.get(url).subscribe(data => this.greeting = data));

to SpringBoot backend where I use CORS annotation:

@CrossOrigin(origins = "http://localhost:4200/", maxAge = 3600)
    @RequestMapping("/api/")
    public Map<String,Object> home() {
        Map<String,Object> model = new HashMap<String,Object>();
        model.put("id", UUID.randomUUID().toString());
        model.put("content", "Hello World");
        return model;
    }

but I'm getting an error that it's blocked and redirects me to login all the time.

Failed to load http://localhost:8080/api: Redirect from 'http://localhost:8080/api' to 'http://localhost:8080/login' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:4200' is therefore not allowed access. 

Is there a way to change that?

I appreciate any hint or help regarding this. I would like to understand why this problem is happening.

Answer 1

You have error in your RequestMapping, as you have used @RequestMapping("/api/"), this will be evaluated as http://your_url/api//. Such mapping is not present in your controller, hence it is giving you CORS Origin error.

Just remove trailing / from @RequestMapping("/api/") so that it will be @RequestMapping("/api").

Your class should look like follows,

@RestController
@CrossOrigin(origins = "http://localhost:4200")
public class DemoController {

    @RequestMapping(value = "/api", method = RequestMethod.GET)
    public Map<String,Object> home() {
        Map<String,Object> model = new HashMap<String,Object>();
        model.put("id", UUID.randomUUID().toString());
        model.put("content", "Hello World");
        return model;
    }
}

Answer 2

This is the problem with your server-side. all you will have to do is do a component in your server-side and it will solve the issue. or refer here

follow this code:

@Component
@Order(Ordered.HIGHEST_PRECEDENCE)
public class RequestFilter implements Filter {

    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {
        HttpServletResponse response = (HttpServletResponse) res;
        HttpServletRequest request = (HttpServletRequest) req;

        response.setHeader("Access-Control-Allow-Origin", "http://localhost:4200");
        response.setHeader("Access-Control-Allow-Methods", "POST, PUT, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Allow-Headers", "x-requested-with");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Credentials", "true");

        if (!(request.getMethod().equalsIgnoreCase("OPTIONS"))) {
            try {
                chain.doFilter(req, res);
            } catch(Exception e) {
                e.printStackTrace();
            }
        } else {
            System.out.println("Pre-flight");
            response.setHeader("Access-Control-Allow-Methods", "POST,GET,DELETE");
            response.setHeader("Access-Control-Max-Age", "3600");
            response.setHeader("Access-Control-Allow-Headers", "authorization, content-type," +
                    "access-control-request-headers,access-control-request-method,accept,origin,authorization,x-requested-with");
            response.setStatus(HttpServletResponse.SC_OK);
        }

    }
    }