delphi三层架构简单实例源码

下面是一个简单的Delphi三层架构实例源码，该实例实现了一个学生管理系统。该系统包含三层架构的三个核心模块：数据访问层（DAL）、业务逻辑层（BLL）和用户界面层（UI）。

1. 数据访问层（DAL）：

该层负责与数据库的交互，包括连接数据库、执行SQL语句等操作。在该实例中，我们将使用ADO组件库来实现数据访问层。

unit DAL;

interface

uses

Classes, DB, ADODB;

type

TStudentDAL = class

private

FConnection: TADOConnection;

public

constructor Create;

function GetStudents: TDataSet;

procedure AddStudent(const AName: string; const AScore: Double);

end;

implementation

constructor TStudentDAL.Create;

begin

FConnection := TADOConnection.Create(nil);

FConnection.ConnectionString := 'Provider=SQLOLEDB.1;Data Source=.;Initial Catalog=StudentsDB;Integrated Security=True';

end;

function TStudentDAL.GetStudents: TDataSet;

var

Query: TADOQuery;

begin

Query := TADOQuery.Create(nil);

Query.Connection := FConnection;

Query.SQL.Text := 'SELECT * FROM Students';

Query.Open;

Result := Query;

end;

procedure TStudentDAL.AddStudent(const AName: string; const AScore: Double);

var

Command: TADOCommand;

begin

Command := TADOCommand.Create(nil);

Command.Connection := FConnection;

Command.CommandText := 'INSERT INTO Students(Name, Score) VALUES(:Name, :Score)';

Command.Parameters.ParamByName('Name').Value := AName;

Command.Parameters.ParamByName('Score').Value := AScore;

Command.Execute;

end;

end.

2. 业务逻辑层（BLL）：

该层负责封装数据访问层的功能，并提供业务逻辑处理。在该实例中，我们将实现对学生数据的增删改查功能。

unit BLL;

interface

uses

Classes, DB, DAL;

type

TStudentBLL = class

private

FStudentDAL: TStudentDAL;

public

constructor Create;

function GetStudents: TDataSet;

procedure AddStudent(const AName: string; const AScore: Double);

end;

implementation

constructor TStudentBLL.Create;

begin

FStudentDAL := TStudentDAL.Create;

end;

function TStudentBLL.GetStudents: TDataSet;

begin

Result := FStudentDAL.GetStudents;

end;

procedure TStudentBLL.AddStudent(const AName: string; const AScore: Double);

begin

FStudentDAL.AddStudent(AName, AScore);

end;

end.

3. 用户界面层（UI）：

该层负责与用户交互，展示数据和接收用户输入。在该实例中，我们将使用VCL组件库来创建一个简单的窗体界面。

unit MainForm;

interface

uses

Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, DB, Grids, DBGrids, BLL;

type

TFormMain = class(TForm)

DBGrid1: TDBGrid;

DataSource1: TDataSource;

ButtonRefresh: TButton;

ButtonAdd: TButton;

EditName: TEdit;

EditScore: TEdit;

LabelName: TLabel;

LabelScore: TLabel;

procedure FormCreate(Sender: TObject);

procedure ButtonRefreshClick(Sender: TObject);

procedure ButtonAddClick(Sender: TObject);

private

FStudentBLL: TStudentBLL;

public

{ Public declarations }

end;

var

FormMain: TFormMain;

implementation

{$R *.dfm}

procedure TFormMain.FormCreate(Sender: TObject);

begin

FStudentBLL := TStudentBLL.Create;

DataSource1.DataSet := FStudentBLL.GetStudents;

end;

procedure TFormMain.ButtonRefreshClick(Sender: TObject);

begin

DataSource1.DataSet := FStudentBLL.GetStudents;

end;

procedure TFormMain.ButtonAddClick(Sender: TObject);

var

Name: string;

Score: Double;

begin

Name := EditName.Text;

Score := StrToFloat(EditScore.Text);

FStudentBLL.AddStudent(Name, Score);

ButtonRefresh.Click;

end;

end.

以上就是一个简单的Delphi三层架构的实例源码。通过将系统的不同逻辑层分离，可以使代码更容易维护和扩展，同时增强了系统的可测试性和可重用性。通过这个实例，你可以了解到Delphi三层架构的基本原理和实现方式。 如果你喜欢我们三七知识分享网站的文章， 欢迎您分享或收藏知识分享网站文章 欢迎您到我们的网站逛逛喔！https://www.37seo.cn/