Improve some code according to code specification

[po-168]

Pre-check

• I am sure that all the content I provide is in English.

Search before asking

• I had searched in the issues and found no similar feature requirement.

Apache Dubbo Component

Java Samples (apache/dubbo-samples)

Descriptions

Improve some code according to code specification

Related issues

No response

Are you willing to submit a pull request to fix on your own?

• Yes I am willing to submit a pull request on my own!

Code of Conduct

• I agree to follow this project's Code of Conduct