Problems that may be encountered when using JavaBean technology for the first time
1. The value of the useBean class attribute is invalid.
Solution: eclipse—set the .class file to WEB-INF\classes
For specific solutions, please refer to the link: https://blog.csdn.net/weixin_43982698/article/details/103220105
2. The classes folder is not displayed in the WEB-INF directory
To solve the connection, please refer to: https://blog.csdn.net/weixin_43982698/article/details/103219980
3. Why the file is placed under WEBINF/classes/user
JavaEE service implementer definition: duWEB-INF/classes in the web project bai structure is the entry point for storing the virtual machine loading classes. This is called a convention. It has now been adopted by all JavaEE service providers. This is a rule.