optimize some code style

[slievrly]

What is the purpose of the change

optimize some code style:

1. @OverRide
2. each if...else should have {}
3. CamelCase
4. remove static methods using instances to reduce compiler calls

Brief changelog

XXXXX

Verifying this change

CI

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[ralf0131]

LGTM, ready to merge when CI passed. (I have triggered the failed CI)