14. The encoding apparatus according to claim 13 , wherein if the characters in the first information group are all third-type characters, the apparatus further comprises a compressing unit, wherein the compressing unit is configured to compress at least one third-type character to make an idle bit appear in the front of the first information group; the generating unit is further configured to record, in the idle bit, that the characters in the first information group are all third-type characters to obtain a third information group, wherein the third information group comprises m bytes; and the adding unit is further configured to add header information to the third information group according to the type of the first information group and the correspondence between the prestored type of the information group and the type of the header information of the information group; or the adding unit is further configured to add header information to the first information group according to the type of the first information group and the correspondence between the prestored type of the information group and the type of the header information of the information group, wherein the header information of the first information group is used to mark that the characters in the first information group are all third-type characters.
13. The encoding apparatus according to claim 9 , wherein: m≦64; and if the prestored type of the information group is an all-data-character type and a non-all-data-character type, the header information of the information group comprises at least two types; or if the prestored type of the information group is an all-data-character type, an all-third-type-character type, and a boundary-character-included type, the header information of the information group comprises at least three types.