java.lang.NoClassDefFoundError: net/sf/ezmorph/Morpher problem solving when using json

I encountered a small problem today, that is, when processing json data, a java.lang.NoClassDefFoundError: net/sf/ezmorph/Morpher exception was reported. At first glance, a certain class was missing, but I felt that json-lib- I also introduced the jdk15.jar package. I didn’t find this class when I opened the jar package. Suddenly, I thought of several dependent jar packages that I forgot to import, commons-beanutils.jar, commons-httpclient.jar, commons-lang.jar, ezmorph.jar, morph-1.0.1.jar can not be missing a package, after importing, the exception is gone!