ssm project project dependency introduction problem

Let's talk about the cause first. When I wrote an interface this morning, I returned a custom result class

The result reported that the return result class R was not converted into a json class. Since I did not write many custom return result sets, the problem was not accurately located, and I thought it was a problem with my own code.

After checking on the Internet, I found that only the following situations were reported for this error

1. There is no getter and setter method for custom return result set, I have

2. There is no dependency on the introduction of conversion, I also have this

 To be on the safe side, I checked the maven next to it, and there are corresponding dependencies.

 Later I found out that it must be in the lib in the artifact in the project structure. . .

 Drag all the dependencies from ssmbuild on the right!

Thanks for this blog, otherwise I will be confused for a long time about java.lang.NoClassDefFoundError, com/alibaba/fastjson/JSONObject error (json lib location reference error) - TONIYH's Blog - CSDN Blog