delphi中Json的处理

一、我们要生成一个Json，格式示例如下：

{
    "mainData": {
        "schollName": "五道口职业技术学院",
        "teacherNamesArray": [
            "张老师",
            "李老师"
        ],
        "teacherDataArray": [
            {
                "name": "张老师",
                "sex": "女",
                "age": 18,
                "salary": 2800.56,
                "onBoarDate": "2023-12-05"
            },
            {
                "name": "李老师",
                "sex": "女",
                "age": 18,
                "salary": 2800.56,
                "onBoarDate": "2022-12-05"
            }
        ],
        "studentDataArray": [
            {
                "studentOverallScore": 523.5,
                "studentData": {
                    "studentName": "Kitty",
                    "studentSex": "女",
                    "studentNo": "17"
                }
            },
            {
                "studentOverallScore": 665,
                "studentData": {
                    "studentName": "韩梅梅",
                    "studentSex": "女",
                    "studentNo": "17"
                }
            }
        ]
    }
}

二、生成这个JSON，代码段如下：

function TForm1.GenerateJson : string;
var
  AMainJson : TJsonObject;
  AteacherNamesArray, AteacherDataArray,AstudentDataArray : TJsonArray;
  AteacherDataJson,AstudentJson,AstudentDataJson : TJsonObject;
begin
  AMainJson := TJsonObject.Create;
  AMainJson.S['schollName'] := '五道口职业技术学院';

  AteacherNamesArray := TJsonArray.Create;
  AteacherNamesArray.Add('张老师');
  AteacherNamesArray.Add('李老师');
  AMainJson.A['teacherNamesArray'] := AteacherNamesArray;

  AteacherDataArray := TJsonArray.Create;
  AteacherDataJson := TJsonObject.Create;
  AteacherDataJson.S['name'] := '张老师';
  AteacherDataJson.S['sex'] := '女';
  AteacherDataJson.I['age'] := 18;
  AteacherDataJson.F['salary'] := 2800.56; //F是Double，D是DateTime
  AteacherDataJson.S['onBoarDate'] := '2023-12-05';
  AteacherDataArray.AddObject(AteacherDataJson);

  AteacherDataJson := TJsonObject.Create;
  AteacherDataJson.S['name'] := '李老师';
  AteacherDataJson.S['sex'] := '女';
  AteacherDataJson.I['age'] := 18;
  AteacherDataJson.F['salary'] := 2800.56; //F是Double，D是DateTime
  AteacherDataJson.S['onBoarDate'] := '2023-12-05';
  AteacherDataArray.AddObject(AteacherDataJson);

  AMainJson.A['teacherDataArray'] := AteacherDataArray;

  AstudentDataArray := TJsonArray.Create;
  AstudentJson := TJsonObject.Create;
  AstudentJson.F['studentOverallScore'] := 523.5;
  AstudentDataJson := TJsonObject.Create;
  AstudentDataJson.S['studentName'] := 'Kitty';
  AstudentDataJson.S['studentSex'] := '女';
  AstudentDataJson.I['studentNo'] := 17;
  AstudentJson.O['studentData'] := AstudentDataJson;
  AstudentDataArray.AddObject(AstudentJson);

  AstudentJson := TJsonObject.Create;
  AstudentJson.F['studentOverallScore'] := 665;
  AstudentDataJson := TJsonObject.Create;
  AstudentDataJson.S['studentName'] := '韩梅梅"';
  AstudentDataJson.S['studentSex'] := '女';
  AstudentDataJson.I['studentNo'] := 17;
  AstudentJson.O['studentData'] := AstudentDataJson;
  AstudentDataArray.AddObject(AstudentJson);


  AMainJson.A['studentDataArray'] := AstudentDataArray;

  Result := AMainJson.ToString;
  Memo1.Lines.Add(Result);

  AMainJson.Free; //托管式节点对象释放

end;

三、解析这个JSON，代码段如下：

procedure TForm1.Button1Click(Sender: TObject);
var
  AresultStr : string;
  AMainJson : TJsonObject;
  AteacherNamesArray, AteacherDataArray,AstudentDataArray : TJsonArray;
  i : Integer;
begin
  AresultStr := GenerateJson;

  AMainJson := TJsonObject.Parse(AresultStr) as TJsonObject;
  AteacherNamesArray := AMainJson.A['teacherNamesArray'];
  AteacherDataArray := AMainJson.A['teacherDataArray'];
  AstudentDataArray := AMainJson.A['studentDataArray'];

  for I := 0 to AteacherNamesArray.Count - 1 do
  begin
    //两种方式
    Memo1.Lines.Add(AteacherNamesArray[i]);
    Memo1.Lines.Add(AteacherNamesArray[i].Value);
  end;

  for I := 0 to AstudentDataArray.Count - 1 do
  begin
    Memo1.Lines.Add(AstudentDataArray[i].O['studentData'].S['studentName']);
  end;

  AMainJson.Free;
end;

四、补充

    1、如果遇到Json串中有很多"\"，"\\","\\\\"，可能会遇到解析不成TJsonObject时，先把他取出来赋值给string，然后再解析这个string

    2、平时如果遇到Free报错时，要注意：.O,.A是指针，不要重复Free或FreeAndNil

    3、超大Json进度要加上TJsonReaderProgressRec，这个参数，可以查看进度