Update the AuthorizedInterceptor to return a JSON error instead of HTML.

src/main/java/space/kklochko/spring_rest_example/interceptors/AuthorizedInterceptor.java

@@ -3,11 +3,17 @@ package space.kklochko.spring_rest_example.interceptors;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.HttpMethod;
 import org.springframework.web.servlet.HandlerInterceptor;
 import space.kklochko.spring_rest_example.security.access.AuthorizedValidator;
 
+import java.io.IOException;
+import java.util.Map;
+import java.util.TreeMap;
+
 public class AuthorizedInterceptor implements HandlerInterceptor {
     @Autowired
     AuthorizedValidator authorizedValidator;
@@ -29,16 +35,39 @@ public class AuthorizedInterceptor implements HandlerInterceptor {
         }
 
         if(accessStatus == null) {
-            response.sendError(HttpServletResponse.SC_UNAUTHORIZED, authorizedValidator.noToken());
+            sendJsonError(response, HttpServletResponse.SC_UNAUTHORIZED, authorizedValidator.noToken());
             return false;
         }
 
         if(!accessStatus) {
-            response.sendError(HttpServletResponse.SC_UNAUTHORIZED, authorizedValidator.accessDeniedNoPermission());
+            sendJsonError(response, HttpServletResponse.SC_FORBIDDEN, authorizedValidator.accessDeniedNoPermission());
             return false;
         }
 
         return true;
     }
+
+    private void sendJsonError(HttpServletResponse response, int status, String message) {
+        response.setStatus(status);
+        response.setContentType("application/json");
+
+        Map<String, Object> errorResponse = new TreeMap<>();
+        errorResponse.put("error", message);
+
+        ObjectMapper objectMapper = new ObjectMapper();
+        String json;
+
+        try {
+            json = objectMapper.writeValueAsString(errorResponse);
+        } catch (JsonProcessingException e) {
+            throw new RuntimeException(e);
+        }
+
+        try {
+            response.getWriter().write(json);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
 }