About the exception caused by: java.lang.classnotfoundexception: com.alibaba.nacos.api.naming.namingmaintainservice

I recently reported this exception when I started the project with springboot. I searched the Internet for various reasons and finally found that:

<dependency>
    <groupId>com.alibaba.nacos</groupId>
    <artifactId>nacos-client</artifactId>
    <version>1.2.0</version>
</dependency>

Plus the above dependence to solve this problem, troubled for more than an hour, wait to calm down just want to understand, record here!!!