delphi TFileStream 流操作2

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unit frmMain;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
  System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Button5: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure Button5Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

  // 测试数据
  TPerson = record
    Name: string;
    Age: Integer;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
  FileStream: TFileStream;

var
  Person: TPerson;
begin
  try
    FileStream := TFileStream.Create('Person.txt', fmCreate);
    // 构造结构体数据
    Person.Name := '萧蔷';
    Person.Age := 20;
    // 写出数据
    FileStream.Write(Person, sizeof(Person));

  finally

    FreeAndNil(FileStream);
  end;
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  FileStream: TFileStream;

var
  Person: TPerson;
begin
  try
    FileStream := TFileStream.Create('Person.txt', fmOpenRead);
    // 设置文件指针的位置
    FileStream.Position := 0;

    // 无法直接读取结构体
    // Self.Memo1.Lines.LoadFromFile('E:\Demo\Person.txt');
    // Self.Memo1.Lines.LoadFromStream(FileStream);

    // 遍历流中的数据(字节)
    while FileStream.Position < FileStream.Size do begin

      FileStream.Read(Person, sizeof(Person));

      Self.Memo1.Lines.Add(Person.Name + ',' + Person.Age.ToString);
    end;
  finally
    FreeAndNil(FileStream);
  end;
end;

procedure TForm1.Button3Click(Sender: TObject);
var
  FileStream: TFileStream;
begin
  try
    FileStream := TFileStream.Create('Memo.txt', fmCreate);

    with Self.Memo1 do begin
      Lines.Add('Hello');
      Lines.Add('World');
      Lines.Add('期待B站粉丝过万');
    end;

    FileStream.WriteComponent(Self.Memo1);

  finally
    FreeAndNil(FileStream);
  end;
end;

procedure TForm1.Button4Click(Sender: TObject);
var
  FileStream: TFileStream;
begin
  try
    FileStream := TFileStream.Create('Memo.txt', fmOpenRead);
    FileStream.ReadComponent(Self.Memo1);
  finally
    FreeAndNil(FileStream);
  end;

end;

procedure TForm1.Button5Click(Sender: TObject);
var
  FileStream: TFileStream;
begin
  Self.Memo1.Lines.LoadFromFile('demo.txt');
  // FileStream := TFileStream.Create('E:\Demo\demo.txt', fmOpenRead);
  // Self.Memo1.Lines.LoadFromStream(FileStream, TEncoding.utf8);
  // FreeAndNil(FileStream);
end;

end.
 

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