1. Right click the project and build path to see if there is a jar error. Remove useless jars and modify the corresponding JDK version

2. Check the SRC source file to see if there is an error in the source file. Found out, really

On the imported package, an error is reported: the import javax.servlet.annotation cannot be resolved  

Then report in problems: eclipse “cannot be resolved to a type” error

— solution:

Finally, in the process of trying, it is found that the version of Tomcat configured by JDK and eclipse does not match. The JDK version is 1.7   Tomcat is 1.6, so some packages don’t

Solution: build path – add library – MyEclipse server Library (some are server runtime, as long as it can be configured to the server, you can try it with the word server)

Then click. Then in

Click the Tomcat version you installed, and then click OK to finish. The mistake disappeared