Delphi Json

{
    "班级1": {
        "classid": "101",
        "teacher": "Lee",
        "age": 25,
        "books": [
            "book1",
            "book2",
            "book3"
        ]
    },
    "班级2": {
        "classid": "102",
        "teacher": "Lee",
        "age": 25,
        "books": [
            "book1",
            "book2",
            "book3"
        ]
    },
    "班级3": {
        "classid": "103",
        "teacher": "Lee",
        "age": 25,
        "books": [
            "book1",
            "book2",
            "book3"
        ]
    },
    "班级4": {
        "classid": "104",
        "teacher": "Lee",
        "age": 25,
        "books": [
            "book1",
            "book2",
            "book3"
        ]
    },
    "班级5": {
        "classid": "105",
        "teacher": "Lee",
        "age": 25,
        "books": [
            "book1",
            "book2",
            "book3"
        ]
    }
}

var
  i,j: Integer;
  jo: TJSONObject;
  root,root2: TJSONObject;
  jArr: TJSONArray;
  sKey,sVal: string;
  aPair: TJSONPair;
  aItem: TJsonValue;
begin
  jo := TJSONObject.Create;
  try
    for i := 1 to 5 do
    begin
      jo.AddPair(Format('班级%d',[i])
        ,TJSONObject.Create
        .AddPair('classid',Format('10%d',[i]))
        .AddPair('teacher','Lee')
        .AddPair('age',TJSONNumber.Create(25))
        .AddPair('books',TJSONArray.Create
          .add('book1').add('book2').add('book3'))
        );
    end;
    FJsonStr := jo.ToString;
    Memo1.Text := JSON_Format(jo.ToString);
  finally
    jo.Free;
  end;

  //Parse Json
  root := TJSONObject.ParseJSONValue(FJsonStr) as TJSONObject;
  if root <> nil then
  try
    //for i := 0 to root.Size - 1 do
    for i := 0 to root.Count - 1 do //同上
    begin
      sKey := root.Get(i).JsonString.value;
      sVal := root.Get(i).JsonValue.toString;
      addLog('[%d] Key:%s,Val:%s',[i,sKey,sVal]);
      //root2 := root.Get(i).JsonValue as TJSONObject;
      root2 := root.GetValue(sKey) as TJSONObject; //同上
      sKey := root2.Get(0).JsonString.value;
      //sVal := root2.Get(0).JsonValue.toString;
      sVal := root2.GetValue(sKey).ToString;
      addLog('[root2[0]] Key:%s,Val:%s',[sKey,sVal]);
      jArr := root2.GetValue('books') as TJSONArray;
      for j := 0 to jArr.Size - 1 do
      begin
        //addLog('Arr%d:%s',[j,jArr.Items[j].ToString]);  //带双引号
        addLog('Arr%d:%s',[j,jArr.Items[j].Value]); //不带双引号
      end;
    end;
  finally
    root.Free;
  end;

  // Update
  root:= TJSONObject.ParseJSONValue(Trim(FJsonStr)) as TJSONObject;
  if root <> nil then
  try
    for i := 0 to Root.Count-1  do
    begin
      sKey := Root.Get(i).JsonString.value;
      sVal := Root.Get(i).JsonValue.toString;
      Root2:= Root.GetValue(sKey) as TJSONObject;
      //aPair:= Root2.Get(0);//
      aPair:= Root2.Get('classid'); //ok
      aItem := TJSONString.Create('New'+IntToStr(i));
      aPair.JsonValue := aItem;
    end;
    FJsonStr := root.ToString;
    addLog(JSON_Format(FJsonStr));
  finally
    root.Free;
  end;
  // Remove
  root:= TJSONObject.ParseJSONValue(Trim(FJsonStr)) as TJSONObject;
  if root <> nil then
  try
    for i := 0 to Root.Count-1  do
    begin
      sKey := Root.Get(0).JsonString.value;
      root.RemovePair(sKey).Free;
      addLog('Remove: ' + sKey);
    end;

  finally
    root.Free;
  end;
end;