经典软件体系结构风格（三）

 MVC 软件体系结构风格
 

#模型-视图-控制器风格常被简称为MVC风格

  --组件：模型、视图、控制器

  --连接件：显式调用、隐式调用、其他机制(例如：Http协议)

#工作机制：

 Model:

 --模型的职责

   1.负责数据存取

   2.负责业务逻辑实现

   3.负责数据验证

#模型：模型是应用程序的核心。它封装内核数据与状态，对模型的修改将扩散到所有视图中。所有需要从模型获取信息的对象都必须注册为模型的视图。

 在事件驱动系统，当信息发生改变，模型通知观察者(observers) (通常是视图)，从而引起视图反应。

#View:

 视图的职责:

–获取用户输入

–向controller发送处理请求

–接收来自Controller的反馈

–将model的处理结果显示给用户

  一个model可能有多个View

#Controller:

  控制器职责:

–接收来自客户的请求

–调用model执行

–调用View显示执行结果

  控制器：控制器是提供给用户进行操作的接口。每个视图与一个控制器组件相关联。控制器接收用户的输入，通常是鼠标移动、键盘输入等。输入事件翻译成服务请求，送到模型或视图。用户只通过控制器与系统交互。

#两个主要分离:

–模型与界面分离

–控制器与视图分离

#优点:

–将各方面问题分解开来考虑，简化了系统设计，保证了系统的可扩展性。

–改变界面不影响应用程序的功能内核，使得系统易于演化开发，可维护性好。

–同一信息可以有不同的展现方式。

–业务逻辑更易测试

 # 案例



 代码：

CarModel.java(模型层)

package com.medel;
import java.io.*;
import java.net.URL;
import java.net.URI;
import javax.swing.*;

import com.view.View;

import java.util.*;

public class CarModel{
private String[] carNameList;
private URL imgURL;
private URL carFileUrl;
private ImageIcon imgIcon;
private String carSelected;
private String bitPrice;
static final String CARFILES = "CarFiles/";
static final String CARIMAGES = "CarImages/";

public CarModel(){
carNameList=new String[200];
}
public void setCarList(String[] cars){
carNameList = cars;
}
public String[] getCarList(){
return carNameList;
}
public void setSelectedCar(String sCar){
carSelected = sCar;
}
public String getSelectedCar(){
return carSelected;
}
public void setBitPrice(String bPrice){
bitPrice = "";
bitPrice = bitPrice + bPrice;
}
public String getBitPrice(){
return bitPrice;
}
public void setupImageIcon(){
String iconStr = CARIMAGES + carSelected+".jpg";
imgIcon = createImageIcon(iconStr);
}
public ImageIcon getImageIcon(){
return imgIcon;
}
public void setCarFileURL(){
try{
String fileURLStr = CARFILES + carSelected+ ".html";
URI uri = (new File(fileURLStr)).toURI();
carFileUrl= uri.toURL();
}
catch (IOException e){
e.printStackTrace();
}
}
public URL getCarFileURL(){
return carFileUrl;
}

protected ImageIcon createImageIcon(String path){
imgURL = getClass().getResource(path);
if (imgURL != null) {
return new ImageIcon(imgURL);
} else {
System.err.println("Couldn't find file: " + path);
return null;
}
}
public void tell(View view ){
view.update();
}
}


 视图层：

View.java

package com.view;

public interface View {
public abstract void update();
}

CarBitView.java

package com.view;
import java.awt.*;
import javax.swing.*;
import com.medel.CarModel;
public class CarBitView extends JFrame implements View{
private JPanel showPanel;
private JLabel bitOfferedLabel;
private JTextArea bitText;
private CarModel model;

public CarBitView(CarModel cmodel) {
super("Car Bit Info View- Observer 2");
model = cmodel;

bitOfferedLabel = new JLabel("Latest bit offered:");
bitText = new JTextArea(4, 20);
bitText.setFont(new Font("Serif", Font.PLAIN, 14));
bitText.setLineWrap(true);
bitText.setWrapStyleWord(true);

Container contentPane = getContentPane();
contentPane.add(bitOfferedLabel, BorderLayout.NORTH);
contentPane.add(bitText, BorderLayout.CENTER);

setSize(400, 150);
setVisible(true);
}

public void update(){
System.out.println("Car bit has been called.");
String sCar= model.getSelectedCar();
String pr = model.getBitPrice();
bitText.append("\n Bit price for "+ sCar + "="+ pr);
}
}


CarGUIView.java

package com.view;
import java.awt.*;
import javax.swing.*;
import java.io.*;
import java.net.URL;
import com.medel.CarModel;
public class CarGUIView extends JFrame implements View{
private JEditorPane editorPane;
private JScrollPane imagePane;
private JScrollPane textPane;
private JSplitPane splitPane;
private JLabel imgLabel;
private CarModel model;

public CarGUIView(CarModel cmodel){
super("窗口1--车的信息");
model = cmodel;
buildUpScrollGUI();
}
private void buildUpScrollGUI(){
imgLabel = new JLabel();
imgLabel.setBackground(Color.green);
imgLabel.setMinimumSize(new Dimension(250, 200));

editorPane = new JEditorPane();
editorPane.setEditable(false);

imagePane = new JScrollPane(imgLabel);
imagePane.getViewport().setBackground(Color.green);

textPane = new JScrollPane(editorPane);
textPane.setMinimumSize(new Dimension(250, 200));

splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT);
splitPane.setLeftComponent(imagePane);
splitPane.setRightComponent(textPane);

Dimension minimumSize = new Dimension(130, 100);
imagePane.setMinimumSize(minimumSize);
textPane.setMinimumSize(new Dimension(100, 100));
splitPane.setDividerLocation(160);
splitPane.setPreferredSize(new Dimension(500, 300));

Container contentPane = getContentPane();
contentPane.add(splitPane);
setSize(400, 150);
setVisible(true);
}

public void update(){
try{
URL url = model.getCarFileURL();
editorPane.setPage(url);
System.out.println("We have been called.");
}
catch (IOException e){
e.printStackTrace();
}
ImageIcon imIcon = model.getImageIcon();
imgLabel.setIcon(imIcon);
imgLabel.validate();
}
}


 控制层：

Controller.java

package com.control;
import java.awt.event.*;
import javax.swing.*;

import com.medel.CarModel;
import com.view.CarBitView;
import com.view.CarGUIView;

import java.net.URL;
public class Controller implements ActionListener{
private CarAuctionGUI objCarGui;
private CarModel cm;
private CarGUIView civ;
private CarBitView cb;
private String carPrice;
private String[] carList;

public Controller(CarAuctionGUI objCarGui,CarModel cm,
CarGUIView civ,CarBitView cb){
this.objCarGui = objCarGui;
this.cm=cm;
this.civ=civ;
this.cb=cb;

carList = objCarGui.getCarList();
cm.setCarList(carList);
}
public void actionPerformed(ActionEvent e){
String searchResult = null;

if (e.getActionCommand().equals(CarAuctionGUI.EXIT)){
System.exit(1);
}
if (e.getActionCommand().equals(CarAuctionGUI.SEARCH)){
String selectedCar = objCarGui.getSelectedCar();
cm.setSelectedCar(selectedCar);
cm.setCarFileURL();
cm.setupImageIcon();
cm.tell(civ); //civ.update();
}
if (e.getActionCommand().equals(CarAuctionGUI.BIT)){
carPrice = objCarGui.getBitPrice();
cm.setBitPrice(carPrice);
cm.tell(cb); //cb.update();
}
}
}


CarAuctionGUI.java

package com.control;
import java.awt.*;
import javax.swing.*;
import java.io.*;
import java.awt.event.*;
import com.medel.CarModel;
import com.view.CarBitView;
import com.view.CarGUIView;
public class CarAuctionGUI extends JPanel {
private JTextField bitInputText;
private JLabel lblCarModel;
private JPanel buttonPanel;
private String[] carList;
private JComboBox cmbCarList;
private static CarModel cm;
private static CarGUIView civ;
private static CarBitView cb;
public static final String SEARCH = "寻找";
public static final String BIT = "确定";
public static final String EXIT = "退出";

public CarAuctionGUI(){
super(new GridLayout(1,0));
setUpGUI();
}
private void setUpGUI(){
cmbCarList = new JComboBox();
String[] cl = getCarList();
setUpCarList(cl);
lblCarModel = new JLabel("二手车种类及年份:");

//Create the open button
JButton srchButton = new JButton(SEARCH);
srchButton.setMnemonic(KeyEvent.VK_S);
JButton exitButton = new JButton(EXIT);
exitButton.setMnemonic(KeyEvent.VK_X);
JButton bitButton = new JButton(BIT);
bitButton.setMnemonic(KeyEvent.VK_X);
bitInputText = new JTextField("请输入你想要的价格：",12);
buttonPanel = new JPanel();

//****************************************************
GridBagLayout gridbag = new GridBagLayout();
buttonPanel.setLayout(gridbag);
GridBagConstraints gbc = new GridBagConstraints();

buttonPanel.add(lblCarModel);
buttonPanel.add(cmbCarList);
buttonPanel.add(srchButton);
buttonPanel.add(bitButton);
buttonPanel.add(exitButton);
buttonPanel.add(bitInputText);

gbc.insets.top = 5;
gbc.insets.bottom = 5;
gbc.insets.left = 5;
gbc.insets.right = 5;
gbc.anchor = GridBagConstraints.EAST;
gbc.gridx = 0;
gbc.gridy = 0;
gridbag.setConstraints(lblCarModel, gbc);
gbc.anchor = GridBagConstraints.WEST;
gbc.gridx = 1;
gbc.gridy = 0;
gridbag.setConstraints(cmbCarList, gbc);
gbc.anchor = GridBagConstraints.EAST;
gbc.insets.left = 2;
gbc.insets.right = 2;
gbc.insets.top = 25;
gbc.anchor = GridBagConstraints.EAST;
gbc.gridx = 0;
gbc.gridy = 3;
gridbag.setConstraints(srchButton, gbc);
gbc.anchor = GridBagConstraints.WEST;
gbc.gridx = 1;
gbc.gridy = 3;
gridbag.setConstraints(exitButton, gbc);
gbc.gridx = 0;
gbc.gridy = 4;
gridbag.setConstraints(bitButton, gbc);
gbc.gridx = 1;
gbc.gridy = 4;
gridbag.setConstraints(bitInputText, gbc);
Controller objButtonHandler = new Controller(this,cm,civ,cb);
srchButton.addActionListener(objButtonHandler);
exitButton.addActionListener(objButtonHandler);
bitButton.addActionListener(objButtonHandler);

add(buttonPanel);
setSize(new Dimension(800, 450));
setVisible(true);
}

public String getSelectedCar() {
return (String) cmbCarList.getSelectedItem();
}

public String getBitPrice(){
return bitInputText.getText();
}

// get the names of all the .html files in a directory
public String[] getCarList(){
File f = new File("CarFiles");
String [] fileNames = f.list();

for(int i=0; i<fileNames.length; i++ ){
int len = fileNames[i].length();
fileNames[i]=fileNames[i].substring(0,len-5);
}
return fileNames;
}

public void setUpCarList(String[] carList){
for(int k=0; k<carList.length; k++) {
cmbCarList.addItem(carList[k]);
}
}

private static void createAndShowGUI() {
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame("MVC pattern demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

CarAuctionGUI newContentPane = new CarAuctionGUI();
newContentPane.setOpaque(true);
frame.setContentPane(newContentPane);

//Display the window.
frame.pack();
frame.setVisible(true);
}

static public void main(String argv[]) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
cm = new CarModel();
civ= new CarGUIView(cm);
cb = new CarBitView(cm);
createAndShowGUI();
}
});
}
}