flutter json转字符串 字符串转json

一段json字符串

   var jsonStr = '{"errorCode": "0",     "message": "成功",     "data": {         "id": 25,         "appLoginUuid": "9c64754d293b487aa16fa266bf6aa9cf",         "userName": "18671045156",         "nickName": "18671045156",         "userType": "2",         "mobileNo": "18671045156",         "status": "3",         "userPhotoUrl": "/picture/logo.png",         "token": "5a7913fc62c974c8d8028a2ea58720d0aef07bba496e351744d3767d525456c4",         "downloadApp": false     } }';

把json字符串转model

    //先转json
   var json = jsonDecode(jsonStr);
    //json转model
   var model = UserResModel.fromJson(json);

存储

  void _saveUserInfo(UserInfo data) async {
    SharedPreferences pref= await SharedPreferences.getInstance();
    //将data转换成json字符串
    var str = json.encode(data);
     pref.setString(DataConst.KEY_UserInfo, str);
     _readUserInfo();
  }

读取

 Future _readUserInfo()async{
      SharedPreferences pref= await SharedPreferences.getInstance();
     final jsonStr = pref.getString(DataConst.KEY_UserInfo);
     print(jsonStr);
     print(jsonStr.runtimeType);
     if(jsonStr != null && jsonStr.length > 0){
        //先将json字符串转json
       Map json = jsonDecode(jsonStr);
    //将json转model
      final model = UserInfo.fromJson(json);
        return model;    
     }
     return null;
  }