Refactor example

[luozhang002]

reactor example:

1. support hot reload
2. support open browser auto

[codecov-io]

Codecov Report

Merging #477 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #477   +/-   ##
=======================================
  Coverage   96.91%   96.91%           
=======================================
  Files          12       12           
  Lines        1427     1427           
  Branches      272      272           
=======================================
  Hits         1383     1383           
  Misses         44       44

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