feat: finish bilingual session auth learning lab

web/WEB-INF/classes/com/demo/action/interceptor/AuthInterceptor.java

@@ -0,0 +1,19 @@
+package com.demo.action.interceptor;
+
+import com.demo.action.LoginAction;
+import com.opensymphony.xwork2.ActionInvocation;
+import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
+
+import java.util.Map;
+
+public class AuthInterceptor extends AbstractInterceptor {
+
+    @Override
+    public String intercept(ActionInvocation invocation) throws Exception {
+        Map<String, Object> session = invocation.getInvocationContext().getSession();
+        if (session != null && session.get(LoginAction.SESSION_USER) != null) {
+            return invocation.invoke();
+        }
+        return "login";
+    }
+}