About the error code returned by Ajax $. Post ()

Garbled characters keep appearing. The key is here. Please refer to the two paragraphs.CodeDifference

Gson = new gson (); string STR = gson. tojson (users); response. setcontenttype ("app/JSON; charset = UTF-8"); response. setheader ("Pragma", "No-Cache"); response. setheader ("cache-control", "No-Cache"); printwriter out = response. getwriter (); out. println (STR); out. flush ();

Gson = new gson (); string STR = gson. tojson (users); printwriter out = response. getwriter (); response. setcontenttype ("app/JSON; charset = UTF-8"); response. setheader ("Pragma", "No-Cache"); response. setheader ("cache-control", "No-Cache"); out. println (STR); out. flush ();

Response. setcontenttype ("application/JSON; charset = UTF-8"); // The former is not garbled, and the latter is garbled. The key lies in the location of this sentence.