八、Delphi10.3读取JSON文件，并修改JSON数组一条内容后保存到文件

一、我们有一个JSON文件，如下：

{
    "在野": [
        {
            "城池": 0,
            "武将": 74,
            "登场年": 190
        },      
        {
            "城池": 0,
            "武将": 11,
            "登场年": 208
        },        
        {
            "城池": 29,
            "武将": 78,
            "登场年": 198
        }
    ],
    "跟随": [
        {
            "父将": 182,
            "子将": 176,
            "登场年": 197
        },
        {
            "父将": 222,
            "子将": 224,
            "登场年": 199
        }
    ]
}

二、我们读取“在野”，代码如下：

//读取JSON文件内容
procedure TForm1.Button1Click(Sender: TObject);
var
  m_Json, m_Json_Item: TJSONObject;
  m_StringStream:      TStringStream;
  m_JsonArr:           TJSONArray;
  I:                   Integer;
begin
  m_StringStream := TStringStream.Create('', TEncoding.UTF8);
  m_StringStream.LoadFromFile(Edit1.Text);
  m_Json := TJSONObject.Create;
  m_Json := TJSONObject.ParseJSONValue(m_StringStream.DataString) as TJSONObject;
  m_JsonArr := m_Json.Values['在野'] as TJSONArray;
  // 第10个
  for I := 0 to m_JsonArr.Count - 1 do
  begin
    m_Json_Item := m_JsonArr.Items[I] as TJSONObject;
    Memo1.Lines.Add(Format('武将:  %s ,登场年： %s ', [m_Json_Item.Values['武将'].Value, m_Json_Item.Values['登场年'].Value]));
  end;
end;

//修改JSON文件内容
procedure TForm1.Button2Click(Sender: TObject);
var
  m_Json, m_Json_Item: TJSONObject;
  m_StringStream:      TStringStream;
  m_JsonArr:           TJSONArray;
begin
  m_StringStream := TStringStream.Create('', TEncoding.UTF8);
  m_StringStream.LoadFromFile(Edit1.Text);

  //读取JSON
  m_Json := TJSONObject.Create;
  m_Json := TJSONObject.ParseJSONValue(m_StringStream.DataString) as TJSONObject;
  m_JsonArr := m_Json.Values['在野'] as TJSONArray;

  // 修改JSON数组内容
  m_Json_Item := m_JsonArr.Items[2] as TJSONObject;
  m_Json_Item.RemovePair('武将');
  m_Json_Item.AddPair('武将', '520');
  m_Json_Item.RemovePair('登场年');
  m_Json_Item.AddPair('登场年', '1314');

  //保存到文件
  m_StringStream.Clear;
  m_StringStream.WriteString(m_Json.ToString);
  m_StringStream.SaveToFile(Edit1.Text);
end;

三、效果如下：