《大话设计模式》之 简单工厂模式 Delphi/C shap /JAVA 实现

{

计算器的功能实现

实现工厂设计模式

通过面向对象的思想，进行设计，所用的编程思想为对象的三大特性：封装，继承，多态

通过实现一个简单的 计算器的功能（输入两个数，进行加，减，乘，除）

思想思路：

1.设计虚拟父类;

2.子类继承父类

3. 通过虚拟方法，进行进行重载

4.工厂类，实例化对象，采用多态

}

unit uOperation;

interface

uses Classes, inifiles;

type

{基础类}

TOperation = class(Tobject)

private

FNumberA: Double;

FNumberB: Double;

public

function GetResult: double; virtual; abstract;

property NumberA: Double read FNumberA write FNumberA;

property NumberB: Double read FNumberB write FNumberB;

constructor create;

destructor Destroy; override;

end;

{加法}

TAdd = class(TOperation)

public

function GetResult: double; override;

end;

{减法}

TSub = class(Toperation)

public

function GetResult: double; override;

end;

{乘法}

TMultiple = class(TOperation)

public

function GetResult: double; override;

end;

{除法}

TDev = class(TOperation)

public

function GetResult: Double; override;

end;

{工厂类}

TOperationFactory = class

private

FOpMap: TStringHash;

public

{可以 GetOperation 定义为类方法，这样就不用创建TOperationFactory 对象，可以直接使用

TOperationFactory.GetOperation 但是在本例子中，由于要创建 FOpMap，所有不能定义 类方法，根据情况灵活应用，还有

简单工厂模式，返回值是父类型}

function GetOperation(Op: string): TOperation;

constructor create;

destructor Destroy; override;

end;

implementation

{ TOperation }

constructor TOperation.create;

begin

end;

destructor TOperation.Destroy;

begin

inherited;

end;

{ TAdd }

function TAdd.GetResult: double;

begin

result := FNumberA + FNumberB;

end;

{ TSub }

function TSub.GetResult: double;

begin

result := FNumberA - FNumberB;

end;

{ TMultiple }

function TMultiple.GetResult: double;

begin

Result := FNumberA * FNumberB;

end;

{ TDev }

function TDev.GetResult: Double;

begin

Result := 0;

if FNumberB <> 0 then

Result := FNumberA / FNumberB;

end;

{ TOperationFactory }

constructor TOperationFactory.create;

begin

FOpMap := TStringHash.Create;

FOpMap.Add('+', 1);

FOpMap.Add('-', 2);

FOpMap.Add('*', 3);

FOpMap.Add('/', 4);

end;

destructor TOperationFactory.Destroy;

begin

FOpMap.Free;

inherited;

end;

function TOperationFactory.GetOperation(Op: string): TOperation;

begin

result := nil;

case FOpMap.ValueOf(Op) of

1: result := TAdd.create;

2: result := TSub.create;

3: result := TMultiple.create;

4: result := TDev.create;

end;

end;

end.

{使用}

unit Unit1;

interface

uses

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs, StdCtrls;

type

TForm1 = class(TForm)

Button1: TButton;

Edit1: TEdit;

Edit2: TEdit;

Edit3: TEdit;

Label1: TLabel;

Label2: TLabel;

Label3: TLabel;

Label4: TLabel;

Edit4: TEdit;

procedure Button1Click(Sender: TObject);

private

{ Private declarations }

public

{ Public declarations }

end;

var

Form1: TForm1;

implementation

uses uOperation;

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);

var

op: TOperation;

OpFact: TOperationFactory;

begin

OpFact := TOperationFactory.create;

op := OpFact.GetOperation(Edit4.Text);

try

if op = nil then exit;

op.NumberA := strtointdef(Edit1.Text, -1);

op.NumberB := strtointdef(Edit2.Text, -1);

edit3.Text := FloatToStr(op.GetResult);

finally

OPFact.Free;

OP.Free;

end;

end;

end.

窗体文件：

object Form1: TForm1

Left = 252

Top = 218

Width = 419

Height = 271

Caption = 'Form1'

Color = clBtnFace

Font.Charset = DEFAULT_CHARSET

Font.Color = clWindowText

Font.Height = -11

Font.Name = 'MS Sans Serif'

Font.Style = []

OldCreateOrder = False

PixelsPerInch = 96

TextHeight = 13

object Label1: TLabel

Left = 120

Top = 56

Width = 60

Height = 13

Caption = '第一个数：'

end

object Label2: TLabel

Left = 120

Top = 88

Width = 60

Height = 13

Caption = '第二个数：'

end

object Label3: TLabel

Left = 120

Top = 144

Width = 36

Height = 13

Caption = '结果：'

end

object Label4: TLabel

Left = 120

Top = 114

Width = 48

Height = 13

Caption = '操作符：'

end

object Button1: TButton

Left = 232

Top = 176

Width = 75

Height = 25

Caption = '计算'

TabOrder = 0

OnClick = Button1Click

end

object Edit1: TEdit

Left = 184

Top = 56

Width = 121

Height = 21

TabOrder = 1

end

object Edit2: TEdit

Left = 184

Top = 88

Width = 121

Height = 21

TabOrder = 2

end

object Edit3: TEdit

Left = 184

Top = 144

Width = 121

Height = 21

TabOrder = 3

end

object Edit4: TEdit

Left = 184

Top = 114

Width = 121

Height = 21

TabOrder = 4

Text = '+'

end

end

// C Sharp 实现

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace OpeartionClass

{

//抽象父类

public class TOpeartion

{

private Double _NumberA = 0;

private double _NumberB = 0;

public Double NumberA

{

get { return _NumberA; }

set { _NumberA = value; }

}

public Double NumberB

{

get { return _NumberB; }

set { _NumberB = value; }

}

public virtual Double GetResult()

{

Double result = 0;

return result;

}

}

// 加法子类

public class TAdd : TOpeartion

{

public override Double GetResult()

{

Double result = 0;

result = NumberA + NumberB;

return result;

}

}

// 减法子类

public class TSub : TOpeartion

{

public override Double GetResult()

{

Double result = 0;

result = NumberA - NumberB;

return result;

}

}

// 乘法子类

public class TMul : TOpeartion

{

public override Double GetResult()

{

Double result = 0;

result = NumberA * NumberB;

return result;

}

}

// 除法子类

public class TDev : TOpeartion

{

public override double GetResult()

{

Double result = 0;

if (NumberB == 0)

throw new Exception("除数不能为零！");

result = NumberA / NumberB;

return result;

}

}

public class TFactoryCreate

{

public static TOpeartion GetOperation(string str)

{

TOpeartion opr = null;

switch (str)

{

case "+":

opr= new TAdd();

break;

case "-":

opr= new TSub();

break;

case "*":

opr = new TMul();

break;

case "/":

opr= new TDev();

break;

}

return opr;

}

}

}

// 调用

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using OpeartionClass;

namespace WindowsFormsApplication1

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

private void button1_Click(object sender, EventArgs e)

{

TOpeartion opr;

opr = TFactoryCreate.GetOperation(textBox3.Text);

opr.NumberA = Convert.ToInt32(textBox1.Text);

opr.NumberB = Convert.ToInt32(textBox2.Text);

textBox4.Text = Convert.ToString(opr.GetResult());

}

}

}

// 窗体文件

namespace WindowsFormsApplication1

{

partial class Form1

{

/// <summary>

/// Required designer variable.

/// </summary>

private System.ComponentModel.IContainer components = null;

/// <summary>

/// Clean up any resources being used.

/// </summary>

/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>

protected override void Dispose(bool disposing)

{

if (disposing && (components != null))

{

components.Dispose();

}

base.Dispose(disposing);

}

#region Windows Form Designer generated code

/// <summary>

/// Required method for Designer support - do not modify

/// the contents of this method with the code editor.

/// </summary>

private void InitializeComponent()

{

this.button1 = new System.Windows.Forms.Button();

this.textBox1 = new System.Windows.Forms.TextBox();

this.textBox2 = new System.Windows.Forms.TextBox();

this.textBox3 = new System.Windows.Forms.TextBox();

this.textBox4 = new System.Windows.Forms.TextBox();

this.label1 = new System.Windows.Forms.Label();

this.label2 = new System.Windows.Forms.Label();

this.label3 = new System.Windows.Forms.Label();

this.label4 = new System.Windows.Forms.Label();

this.SuspendLayout();

//

// button1

//

this.button1.Location = new System.Drawing.Point(191, 168);

this.button1.Name = "button1";

this.button1.Size = new System.Drawing.Size(64, 27);

this.button1.TabIndex = 0;

this.button1.Text = "计算";

this.button1.UseVisualStyleBackColor = true;

this.button1.Click += new System.EventHandler(this.button1_Click);

//

// textBox1

//

this.textBox1.Location = new System.Drawing.Point(93, 23);

this.textBox1.Name = "textBox1";

this.textBox1.Size = new System.Drawing.Size(120, 21);

this.textBox1.TabIndex = 1;

//

// textBox2

//

this.textBox2.Location = new System.Drawing.Point(93, 50);

this.textBox2.Name = "textBox2";

this.textBox2.Size = new System.Drawing.Size(120, 21);

this.textBox2.TabIndex = 2;

//

// textBox3

//

this.textBox3.Location = new System.Drawing.Point(93, 77);

this.textBox3.Name = "textBox3";

this.textBox3.Size = new System.Drawing.Size(120, 21);

this.textBox3.TabIndex = 3;

//

// textBox4

//

this.textBox4.Location = new System.Drawing.Point(93, 104);

this.textBox4.Name = "textBox4";

this.textBox4.Size = new System.Drawing.Size(120, 21);

this.textBox4.TabIndex = 4;

//

// label1

//

this.label1.AutoSize = true;

this.label1.Location = new System.Drawing.Point(11, 26);

this.label1.Name = "label1";

this.label1.Size = new System.Drawing.Size(77, 12);

this.label1.TabIndex = 5;

this.label1.Text = "第一个参数：";

//

// label2

//

this.label2.AutoSize = true;

this.label2.Location = new System.Drawing.Point(12, 50);

this.label2.Name = "label2";

this.label2.Size = new System.Drawing.Size(77, 12);

this.label2.TabIndex = 6;

this.label2.Text = "第二个参数：";

//

// label3

//

this.label3.AutoSize = true;

this.label3.Location = new System.Drawing.Point(12, 80);

this.label3.Name = "label3";

this.label3.Size = new System.Drawing.Size(65, 12);

this.label3.TabIndex = 7;

this.label3.Text = "运算符号：";

//

// label4

//

this.label4.AutoSize = true;

this.label4.Location = new System.Drawing.Point(11, 113);

this.label4.Name = "label4";

this.label4.Size = new System.Drawing.Size(41, 12);

this.label4.TabIndex = 8;

this.label4.Text = "结果：";

//

// Form1

//

this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);

this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;

this.ClientSize = new System.Drawing.Size(296, 225);

this.Controls.Add(this.label4);

this.Controls.Add(this.label3);

this.Controls.Add(this.label2);

this.Controls.Add(this.label1);

this.Controls.Add(this.textBox4);

this.Controls.Add(this.textBox3);

this.Controls.Add(this.textBox2);

this.Controls.Add(this.textBox1);

this.Controls.Add(this.button1);

this.Name = "Form1";

this.Text = "Form1";

this.ResumeLayout(false);

this.PerformLayout();

}

#endregion

private System.Windows.Forms.Button button1;

private System.Windows.Forms.TextBox textBox1;

private System.Windows.Forms.TextBox textBox2;

private System.Windows.Forms.TextBox textBox3;

private System.Windows.Forms.TextBox textBox4;

private System.Windows.Forms.Label label1;

private System.Windows.Forms.Label label2;

private System.Windows.Forms.Label label3;

private System.Windows.Forms.Label label4;

}

}

// JAVA 实现

//实现抽象类

package OperationFactory;

public abstract class Operation {

private double NumberA;

private double NumberB;

public double GetNumberA()

{

return NumberA;

}

public void SetNumberA(double numbera)

{

this.NumberA=numbera;

}

public double GetNumberB()

{

return NumberB;

}

public void SetNumberB(double numberb)

{

this.NumberB=numberb;

}

public abstract double getresult()throws Exception;

}

//实现子类 加法 OPerationAdd

package OperationFactory;

public class OperationAdd extends Operation {

@Override

public double getresult()throws Exception {

double result = 0;

result = GetNumberA() + GetNumberB();

return result;

}

}

//实现子类 除法 OperationDev

package OperationFactory;

public class OperationDev extends Operation {

@Override

public double getresult() throws Exception {

double result=0;

if (GetNumberB()==0)

throw new Exception("除数不能为0");

result=GetNumberA()/GetNumberB();

return result;

}

}

//实现子类 乘法 OPerationMul

package OperationFactory;

public class OperationMul extends Operation {

@Override

public double getresult() throws Exception {

// TODO Auto-generated method stub

double result=0;

result=GetNumberA() * GetNumberB();

return result;

}

}

//实现子类 减法 OperationSub

package OperationFactory;

public class OperationSub extends Operation {

@Override

public double getresult() throws Exception {

double result = 0;

result = GetNumberA() - GetNumberB();

return result;

}

}

// 工厂类 OperateFactory

package OperationFactory;

public class OperateFactory {

public static Operation CreateFactory(String sOperat){

Operation opr=null;

if ("+".equalsIgnoreCase(sOperat))

{

opr=new OperationAdd();

}else if ("-".equalsIgnoreCase(sOperat))

{

opr=new OperationSub();

}else if ("*".equalsIgnoreCase(sOperat))

{

opr=new OperationMul();

}else if ("/".equalsIgnoreCase(sOperat))

{

opr=new OperationDev();

}

return opr;

}

}

总结： 上面我用三种语言- Delphi 、C Sharp、 JAVA 实现了简单工厂设计模式。它们都是面向对象语言特性，都可以实现其模式设计。这样做的目的是一种尝试，对于初学者来，可以洞悉其中的异同，对于同时需要掌握多门开发语言的人来说，可以做一个比较，印象会更深刻。