人生最曼妙的风景，竟是内心的淡定与从容！
Think about it carefully, maybe the jdk in the IDE is not set up properly, so System.outis not introduced?
System.out
Written in the function because the out object is not defined, and if written directly inside the Jsp page, out is the default built-in object out of the Jsp page.
Thanks to the two classmates upstairs. The servlet-api.jar in tomcat was not introduced.
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
Think about it carefully, maybe the jdk in the IDE is not set up properly, so
System.outis not introduced?Written in the function because the out object is not defined, and if written directly inside the Jsp page, out is the default built-in object out of the Jsp page.
Thanks to the two classmates upstairs. The servlet-api.jar in tomcat was not introduced.