一般來說，可以把系統粗略的分為三個層次，視圖層，簡稱為View，它負責數據的輸出和輸入；業務層，簡稱為Model，它代表程序的實際業務；控制層，簡稱為Controller，處理界面的相應并調用業務層進行處理，有時把View和Controller兩層合稱為UI層。
在程序發展的歷史上，MVC模式進過了多次演化，MVC1和MVC2是兩種比較典型的模式，它們的區別主要在于View和Model的聯系方式上。
（1
） MVC1
模式
這種模式主要用于桌面程序,使用觀察者模式實現,具體來說就是讓View充當觀察者來觀察Model的變化,而用戶交互控制的地方用匿名類的方式統一放在controller中.
View接受用戶輸入,并將交互數據傳遞到Controller.
Controller統一進行處理命令,交由Model處理具體的業務.
進過處理Model更新后,通知View進行更新.
這種模式在舊的桌面應用程序使用較多，但是它的Model必須繼承Observable類，View必須實現Observer接口，人為加大了繼承體系的復雜度；而且Model通知View的方式使View必須了解Model的結構，無謂的加大了兩個類的耦合程度。這些缺點使這種模式逐漸淡出了程序舞臺。
代碼如下:
Control類:
package
?com.sitinspring;
import
?java.awt.event.ActionEvent;
import
?java.awt.event.ActionListener;
import
?java.awt.event.WindowAdapter;
import
?java.awt.event.WindowEvent;
/**?*/
/**
?*?控制類
?*?
?*?
@author
?sitinspring(junglesong@gmail.com)
?*?
?*?@date?2007-11-5
?
*/
public
?
class
?Mvc1Ctrl?
{
????
private
?Mvc1View?view;
????
private
?Mvc1Model?model;
????
public
?Mvc1Ctrl()?
{
????????view?
=
?
new
?Mvc1View();
????????model?
=
?
new
?Mvc1Model();
????????model.addObserver(view);
????????handleEvents();
????}
????
//
?處理事件響應
????
private
?
void
?handleEvents()?
{
????????addCloseLintener();
????????addButtonListener();
????????addButtonListener2();
????}
????
//
?窗體關閉事件相應
????
private
?
void
?addCloseLintener()?
{
????????view.addWindowListener(
new
?WindowAdapter()?
{
????????????
public
?
void
?windowClosing(WindowEvent?e)?
{
????????????????System.out.println(
"
Exit?MVC1
"
);
????????????????System.exit(
0
);
????????????}
????????}
);
????}
????
private
?
void
?addButtonListener()?
{
????????view.getButton().addActionListener(
new
?ActionListener()?
{
????????????
public
?
void
?actionPerformed(ActionEvent?e)?
{
????????????????model.showText();
????????????}
????????}
);
????}
????
????
private
?
void
?addButtonListener2()?
{
????????view.getButton2().addActionListener(
new
?ActionListener()?
{
????????????
public
?
void
?actionPerformed(ActionEvent?e)?
{
????????????????model.showText2();
????????????}
????????}
);
????}
}
視圖類(View):
package
?com.sitinspring;
import
?java.awt.Dimension;
import
?java.awt.GridLayout;
import
?java.awt.Toolkit;
import
?java.util.Observable;
import
?java.util.Observer;
import
?javax.swing.JButton;
import
?javax.swing.JFrame;
import
?javax.swing.JLabel;
/**?*/
/**
?*?視圖類(View)
?*?
?*?
@author
?sitinspring(junglesong@gmail.com)
?*?
?*?@date?2007-11-5
?
*/
public
?
class
?Mvc1View?
extends
?JFrame?
implements
?Observer?
{
????
private
?
static
?
final
?
long
?serialVersionUID?
=
?
621145935910133202L
;
????
private
?JButton?button;
????
private
?JLabel?label;
????
private
?JButton?button2;
????
private
?JLabel?label2;
????
public
?Mvc1View()?
{
????????locateView(
300
,?
200
);
????????
this
.setTitle(
"
MVC1?Program
"
);
????????setupComponents();
????????
this
.setVisible(
true
);
????}
????
//
?當模塊更新時,此函數會被調用
????
public
?
void
?update(Observable?o,?Object?arg)?
{
????????Mvc1Model?model?
=
?(Mvc1Model)?o;
????????
if
?(model.getUpdateState().equals(Mvc1UpdateState.UpdateLabel))?
{
????????????label.setText(model.getResponseText());
????????}
?
else
?
if
?(model.getUpdateState().equals(Mvc1UpdateState.UpdateLabel2))?
{
????????????label2.setText(model.getResponseText());
????????}
????}
????
//
?定位程序在屏幕正中并設置程序大小
????
private
?
void
?locateView(
int
?width,?
int
?height)?
{
????????Dimension?screenSize?
=
?Toolkit.getDefaultToolkit().getScreenSize();
????????
this
.setSize(width,?height);
????????
this
.setLocation(screenSize.width?
/
?
2
?
-
?width?
/
?
2
,?screenSize.height
????????????????
/
?
2
?
-
?height?
/
?
2
);
????}
????
//
?初始化內部組件
????
private
?
void
?setupComponents()?
{
????????button?
=
?
new
?JButton(
"
點擊響應事件1
"
);
????????label?
=
?
new
?JLabel(
"
??等待事件響應1
"
);
????????button2?
=
?
new
?JButton(
"
點擊響應事件2
"
);
????????label2?
=
?
new
?JLabel(
"
??等待事件響應2
"
);
????????setLayout(
new
?GridLayout(
2
,?
2
));
????????add(button);
????????add(label);
????????add(button2);
????????add(label2);
????}
????
public
?JButton?getButton()?
{
????????
return
?button;
????}
????
public
?JButton?getButton2()?
{
????????
return
?button2;
????}
}
模塊類:
package
?com.sitinspring;
import
?java.util.Observable;
/**?*/
/**
?*?模塊類
?*?
@author
?sitinspring(junglesong@gmail.com)
?*
?*?@date?2007-11-5
?
*/
public
?
class
?Mvc1Model?
extends
?Observable
{
????
private
?String?responseText;
????
private
?String?updateState;
????
????
//
?用于通知View更新,此函數被調用后View的update函數會被調用
????
private
?
void
?notifyView()
{
????????setChanged();?????????
????????notifyObservers();
????}
????
????
public
?
void
?showText()
{
????????updateState
=
Mvc1UpdateState.UpdateLabel;
????????responseText
=
"
??事件1響應完畢
"
;
????????notifyView();
????}
????
????
public
?
void
?showText2()
{
????????updateState
=
Mvc1UpdateState.UpdateLabel2;
????????responseText
=
"
??事件2響應完畢
"
;
????????notifyView();
????}
????
public
?String?getResponseText()?
{
????????
return
?responseText;
????}
????
public
?String?getUpdateState()?
{
????????
return
?updateState;
????}
}
更新狀態輔助類:
package
?com.sitinspring;
public
?
class
?Mvc1UpdateState
{
????
public
?
static
?
final
?String?UpdateLabel
=
"
updateLabel
"
;
????
public
?
static
?
final
?String?UpdateLabel2
=
"
updateLabel2
"
;
}
MVC1示例代碼下載:
http://www.aygfsteel.com/Files/sitinspring/MVC1.rar
（2）MVC2模式
這種模式首見于網絡程序，起初因為Model無法通知到Web程序的界面而發明，這種模式采用Controller做中介者，一方面取得View的輸入，然后交由Model層處理，之后再把返回的數據傳遞到View。
View接受用戶輸入,并傳遞到Controller.
Controller統一進行處理命令,交由Model處理具體的業務.
進過處理Model更新后,Controller會選一個View并把Model內容傳遞(request,session)給它(forward).
然后View進行顯示.
這種模式相對
MVC
優勢很明顯，首先
Model
和
View
無需繼承甚么東西，其次
Model
和
View
無需了解對方的存在，只需準備相應的接口而已；缺點是
Controller
層變得相對復雜了。
代碼如下:
控制類:
package
?com.sitinspring;
import
?java.awt.event.ActionEvent;
import
?java.awt.event.ActionListener;
import
?java.awt.event.WindowAdapter;
import
?java.awt.event.WindowEvent;
/**?*/
/**
?*?控制類
?*?
?*?
@author
?sitinspring(junglesong@gmail.com)
?*?
?*?@date?2007-11-5
?
*/
public
?
class
?Mvc2Ctrl?
{
????
private
?Mvc2View?view;
????
private
?Mvc2Model?model;
????
public
?Mvc2Ctrl()?
{
????????view?
=
?
new
?Mvc2View();
????????model?
=
?
new
?Mvc2Model();
????????handleEvents();
????}
????
//
?處理事件響應
????
private
?
void
?handleEvents()?
{
????????addCloseLintener();
????????addButtonListener();
????????addButtonListener2();
????}
????
//
?窗體關閉事件相應
????
private
?
void
?addCloseLintener()?
{
????????view.addWindowListener(
new
?WindowAdapter()?
{
????????????
public
?
void
?windowClosing(WindowEvent?e)?
{
????????????????System.out.println(
"
Exit?MVC2
"
);
????????????????System.exit(
0
);
????????????}
????????}
);
????}
????
private
?
void
?addButtonListener()?
{
????????view.getButton().addActionListener(
new
?ActionListener()?
{
????????????
public
?
void
?actionPerformed(ActionEvent?e)?
{
????????????????view.getLabel().setText(model.getText());
????????????}
????????}
);
????}
????
????
private
?
void
?addButtonListener2()?
{
????????view.getButton2().addActionListener(
new
?ActionListener()?
{
????????????
public
?
void
?actionPerformed(ActionEvent?e)?
{
????????????????view.getLabel2().setText(model.getText2());
????????????}
????????}
);
????}
}
視圖類:
package?com.sitinspring;
import?java.awt.Dimension;
import?java.awt.GridLayout;
import?java.awt.Toolkit;
import?javax.swing.JButton;
import?javax.swing.JFrame;
import?javax.swing.JLabel;
/**?*//**
?*?視圖類(View)
?*?
?*?@author?sitinspring(junglesong@gmail.com)
?*?
?*?@date?2007-11-5
?*/
public?class?Mvc2View?extends?JFrame?{
????private?static?final?long?serialVersionUID?=?621145935910133202L;
????private?JButton?button;
????private?JLabel?label;
????private?JButton?button2;
????private?JLabel?label2;
????public?Mvc2View()?{
????????locateView(300,?200);
????????this.setTitle("MVC2?Program");
????????setupComponents();
????????this.setVisible(true);
????}
????//?定位程序在屏幕正中并設置程序大小
????private?void?locateView(int?width,?int?height)?{
????????Dimension?screenSize?=?Toolkit.getDefaultToolkit().getScreenSize();
????????this.setSize(width,?height);
????????this.setLocation(screenSize.width?/?2?-?width?/?2,?screenSize.height
????????????????/?2?-?height?/?2);
????}
????//?初始化內部組件
????private?void?setupComponents()?{
????????button?=?new?JButton("點擊響應事件1");
????????label?=?new?JLabel("??等待事件響應1");
????????button2?=?new?JButton("點擊響應事件2");
????????label2?=?new?JLabel("??等待事件響應2");
????????setLayout(new?GridLayout(2,?2));
????????add(button);
????????add(label);
????????add(button2);
????????add(label2);
????}
????public?JButton?getButton()?{
????????return?button;
????}
????public?JButton?getButton2()?{
????????return?button2;
????}
????public?JLabel?getLabel()?{
????????return?label;
????}
????public?JLabel?getLabel2()?{
????????return?label2;
????}
} 模塊類:
?
package?com.sitinspring;
/**?*//**
?*?模塊類
?*?@author?sitinspring(junglesong@gmail.com)
?*
?*?@date?2007-11-5
?*/
public?class?Mvc2Model{
????public?String?getText(){
????????return?"??事件1響應完畢";
????}
????
????public?String?getText2(){
????????return?"??事件2響應完畢";
????}
} MVC2示例代碼下載:
http://www.aygfsteel.com/Files/sitinspring/MVC2.rar
|