[1] Qt Linguist Manual: Translators | Documentation | Qt Project ( 版) <http://qt-project.org/doc/qt-4.8/linguist-translators.html>
QM Qt message files
are binary files that contain translations used by an application at run-time. These files are generated by lrelease, but can also be generated by Qt Linguist.
[2] Qt .qm — Translate Toolkit 1.13.0-rc1 documentation ( 版) <http://translate-toolkit.readthedocs.org/en/latest/formats/qm.html>
A .qm file is a compiled Qt linguist file. In many ways it is similar to Gettext, in that it uses a hashing table to lookup the translated text. In older version they store only the hash and the translation which doesn’t make the format useful for recovering translated text.