CommentDaoTest

isXXXExists(XXX entity)
{
}
judge if entity is null
Revert "CommentDaoTest"

This reverts commit 957ca22e605e65dc59c18009062c497617d2c060.
Revert "Revert "CommentDaoTest""

This reverts commit f0f36a1a158cda592d95faef222ec98c132e3a37.