When I read some text from a dwg file (CAD 2000 version), I get some characters like "\M+5BFAA\M+5B9D8", but it should be the Chinese character "开关". This error appears when I use Java platform in Linux, on Windows it works well.

DWG file version CAD 2000 contents text string in multi byte coding. Higher dwg versions store text in unicode. So for conversion multi byte to unicode you need to initialize map by next way once during start your application - OdCharMapper.initialize("adinit.dat"). "adinit.dat" must be with full path place.

More detail information about font support you can find here (ODA login required).