當你嘗試在Spring Boot項目中使用iframe標簽時，瀏覽器會報“in a frame because it set 'X-Frame-Options' to 'deny'.”的錯誤。解決辦法如下：

@EnableWebSecurity
public class WebSecurityConfig extends
        WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            // ...
            .headers()
                .frameOptions().sameOrigin()
                .httpStrictTransportSecurity().disable();
    }
}

參考https://docs.spring.io/spring-security/site/docs/current/reference/html/headers.html