Map map = new HashMap();
map.put("1", new byte[]{1, 2, 3});
String fastjsonJson = JSON.toJSONString(map);
System.out.println(fastjsonJson);
String fastjsonJson2 = JSON.toJSON(map).toString();
System.out.println(fastjsonJson2);

得出的结果为

{"1":"AQID"}
{"1":[1,2,3]}