生成JSON：

Gson gson =newGson();

User user =newUser("小紅",24);

String jsonObject = gson.toJson(user).tostring();? ? ? ? // {"name":"小紅","age":24}

解析JSON：

Gson gson =newGson();

String jsonString ="{\"name\":\"小紅\",\"age\":24}";

User user = gson.fromJson(jsonString, User.class);