Problem description: When IDEA opens other people's web projects, the web folder does not have a small blue dot, and an error occurs when configuring the Tomcat server. Follow the steps below to solve the problem step by step.
1. Open File–>Project Structure and operate as shown in the figure below
2. Click Artifacts in the left column of this page, as shown below
Click ok–>apply–>ok in sequence. After clicking web, there will be a small blue dot.
3. Add Tomcat server, as shown below
Change the file name in the first step of the picture below to be consistent with the project name
