基于MVC模式下的二手车拍卖平台设计

课程名称：《软件体系结构与设计模式》
实验项目名称：基于MVC模式下的二手车拍卖平台设计

实验内容按下列要求编写程序并上机调试运行：

拍卖系统要又三个显示界面，分别是车体图片，文字描述和出价区。

将系统分解成MVC三个类进行方法设计。

M和V必须观察者模式进行设计。

使用SWING进行界面设计。

按钮点击，必须更新车型和图片，并用时间驱动结构进行设计。

额外要求：要求报价必须只能提高，不等减少，如减少弹出警告窗口。

代码15元1份，有需要联系+qq2421442475

以下写类图和代码

类图：

分析与代码展示：

其中，CarGUI提供用户输入界面，代表用户；CarModel为MVC体系结构中的模型部分（Model）；BitView和SearchView代表视图部分（View）；而Controller为控制器部分。
用户通过使用CarGUI图形界面在的列表选择待拍卖的车，单击“Search”按钮，获取车的图片和文字说明；然后输入竞拍价，单击“Bit”按钮，竞拍价将显示在拍卖价格显示区域上；若下次的拍卖价格比这次的价格低，则会弹出警告窗口消息框并会在拍卖价格显示区域上显示一条信息：“Bit price for”+CarName+“：”+“illegal bit price”。
程序运行结果图如下图所示。

图1

图2

图3

图4

Observer类

public interface Observer {public void update(Observable subject);
}

Observable类

public interface Observable {public void register(Observer obs);public void notifyObservers();
}

在该设计类图中设计了两个接口类:Observable与Observer，Model类实现Observable接口，而View类实现Observer接口。也就是说Model对象是被观察者而View对象是观察者。根据观察者机制，被观察者类应该包含registerObserver( )、notifyObservers( )方法,其功能是在被观察者对象中利用registerObserver( )加入被观察者对象，并且当被观察者的数据或者状态有了改变的时候，利用notifyObservers( )方法通知观察者。此时,观察者类中的update( )方法将自动运行，达到及时更新观察者的目的。

CarModel类

import javax.swing.*;
import java.util.ArrayList;public class CarModel implements Observable{private ArrayList<Observer> observers;private String carName;private String bitPrice;private ImageIcon icon;String [] carSelected = {"Honda Accord"," "," ","Made in 2005, used by the Department of defense.","Mileage: 60,000 miles.","5-speed automatic (25 city/36 highway) transmission?"," "," "," "," "};String [] car2Selected = {"Honda Civic"," "," ","Made in 2006,used by the New York State government ","Mileage 40,4000 miles.","5-speed manual (25 city/36 highway) transmission?","140-hp, 1.8-Liter, 16-Valve SOHC i-VTEC? 4-cylinder engine"," "};String [] car3Selected = {"Toyota Camry"," "," ","Made in 2003, used by the Washington State government","Mileage: 100,000 miles.","5-speed automatic (25 city/36 highway) transmission?","140-hp, 1.8-Liter, 16-Valve SOHC i-VTEC? 4-cylinder engine"," "};String [] car4Selected = {"Toyota Corolla"," "," ","Made in 2002, used by the Washington State government","Mileage: 120,000 miles.","5-speed automatic (25 city/36 highway) transmission?", "140-hp, 1.8-Liter, 16-Valve SOHC i-VTEC? 4-cylinder engine"," "};public CarModel() {observers = new ArrayList<Observer>();}public String getCarName() {return carName;}public String getBitPrice() {return bitPrice;}public void setCarName(String carName) {this.carName = carName;notifyObservers();}public void setBitPrice(String bitPrice) {this.bitPrice = bitPrice;notifyObservers();}public ImageIcon getImage() {return this.icon;}public void setImage(String file) {this.icon = new ImageIcon(file);notifyObservers();}@Overridepublic void register(Observer obs) {observers.add(obs);}@Overridepublic void notifyObservers() {for (int i = 0; i < observers.size(); i++) {observers.get(i).update(this);}}
}

BitView类

import javax.swing.*;public class BitView implements Observer{private final CarModel cm;private final CarGUI cg;public BitView(CarModel cm,CarGUI cg) {this.cm = cm;this.cg=cg;}@Overridepublic void update(Observable subject) {if ( subject == cm){String name= cm.getCarName();String p = cm.getBitPrice();String text=" Bit price for "+ name + " : "+ p;ImageIcon imIcon = cm.getImage();cg.setIcon(imIcon);//更新拍卖车图片区域cg.showPrice(text);//更新拍卖价格显示区域}}}

SearchView类

import javax.swing.*;public class SearchView implements Observer {private final CarModel cm;private final CarGUI cg;public SearchView(CarModel cm,CarGUI cg) {this.cm = cm;this.cg=cg;}@Overridepublic void update(Observable subject) {if ( subject == cm){ImageIcon imIcon = cm.getImage();cg.setIcon(imIcon);}}
}

其中，CarGUI提供了用户输入界面，代表用户。注意，在类CarGUI中，创建与初始化了CarModel、SearchView和BitView对象，并且调用CarModel中的register(Observer obs)，分别将SearchView和BitView的对象注册到该CarModel对象。
①箱子布局管理，主要是Swing包中的Box来进行盒子布局，包括两种箱子：一种是水平箱子、一种是垂直箱子。构造方法如下：
Box box=Box.createHorizontalBox()//创建水平箱子对象
Box box=Box.createVertiaclBox()//创建垂直箱子对象
箱子创建好后，用add()把组件添加到箱子里面
②设置控件间隔的方法
Box.createHorizontalStrut(int width)//设置左右两个组件的宽度
Box.createVerticalStrut(int height)//设置上下两个组件的距离

CarGUI类

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;public class CarGUI {private static CarModel carModel;private static BitView bitView;private static SearchView searchView;private JComboBox carSelector;String [] carNameList = {"Honda Accord-2005","Honda Civic-2006","Toyota Camry-2003","Toyota Corolla-2002"};String [] carSelected = {"Honda Accord"," "," ","Made in 2005, used by the Department of defense.","Mileage: 60,000 miles.","5-speed automatic (25 city/36 highway) transmission?"," "};JFrame frame = new JFrame("MVC pattern 二手车拍卖");JTextArea bitShownText = new JTextArea("Bit price for each car will be shown here",4,20);JTextField bitInputText = new JTextField("Offer your bit price",10);JLabel imgLabel = new JLabel();JList textList = new JList<>(carSelected);Icon icon=new ImageIcon("images\\Honda Accord-2005.jpg");//组装视图的函数public void init(){//注册被观察者与观察者carModel = new CarModel();bitView= new BitView(carModel,this);searchView = new SearchView(carModel, this);carModel.register(bitView);carModel.register(searchView);//窗口大小frame.setBounds(200,200,500,300);//组装顶部相关元素Box pBox = Box.createVerticalBox();//组装车的类型和下拉框Box uBox = Box.createHorizontalBox();JLabel  carlbl = new JLabel("Cars:");carSelector = new JComboBox<>(carNameList);carSelector.setMaximumRowCount(4);uBox.add(Box.createHorizontalStrut(50));uBox.add(carlbl);uBox.add(Box.createHorizontalStrut(10));uBox.add(carSelector);uBox.add(Box.createHorizontalStrut(10));//组装搜索和退出按钮Box btn2Box = Box.createHorizontalBox();JButton searchBtn = new JButton("Search");JButton exitBtn = new JButton("Exit");btn2Box.add(Box.createHorizontalStrut(5));btn2Box.add(searchBtn);btn2Box.add(Box.createHorizontalStrut(5));btn2Box.add(exitBtn);btn2Box.add(Box.createHorizontalStrut(100));//组装Bit和文本框Box btn1Box = Box.createHorizontalBox();JButton bitButton = new JButton("Bit");bitInputText.setBackground(Color.green);btn1Box.add(Box.createHorizontalStrut(5));btn1Box.add(bitButton);btn1Box.add(Box.createHorizontalStrut(20));btn1Box.add(bitInputText);btn1Box.add(Box.createHorizontalStrut(30));//组装左上部分pBox.add(Box.createVerticalStrut(10));pBox.add(uBox);pBox.add(Box.createVerticalStrut(20));pBox.add(btn2Box);pBox.add(Box.createVerticalStrut(20));pBox.add(btn1Box);pBox.add(Box.createVerticalStrut(20));//组装右上文本域JScrollPane bitInfo = new JScrollPane(bitShownText);//拍卖价格显示区域//组装顶部Box topBox = Box.createHorizontalBox();topBox.add(pBox);topBox.add(bitInfo);//组装左下imgLabel.setIcon(icon);JScrollPane imagePane = new JScrollPane(imgLabel);//组装右下JScrollPane bigSplitPane = new JScrollPane(textList);//组装底部相关元素Box baseBox= Box.createHorizontalBox();baseBox.add(imagePane);baseBox.add(bigSplitPane);//组装整体Box holeBOX = Box.createVerticalBox();holeBOX.add(topBox);holeBOX.add(baseBox);//添加监听器Controller buttonTeam = new Controller(this,carModel);searchBtn.addActionListener(buttonTeam);exitBtn.addActionListener(buttonTeam);bitButton.addActionListener(buttonTeam);frame.add(holeBOX);frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);frame.pack();//调整此窗口的大小，以适合其子组件的首选大小和布局frame.setVisible(true);}public String getBitPrice(){return bitInputText.getText();}public String getCarName(){return carSelector.getSelectedItem().toString();//　getSelectedItem()：获得所选项的内容。}public void showPrice(String text){bitShownText.setText(text);}public void setIcon(ImageIcon icon) {imgLabel.setIcon(icon);imgLabel.validate();}public void setData(String[] name) {textList.setListData(name);//更新文字信息}
}

类CarModel封装了所有关于二手车拍卖的核心数据和提供给类Contoller和类SerachView、BitView调用的方法，该类保持了与其他三个类的高度的独立性。这里Conroller类实现了ActionListener接口。在负责用户输人的类CarGUI中，所有的按钮Search 与Bit 都添加了Controller的对象。这样，当一个按钮对象被按下时所产生的事件触发了Controller对象的actionPerformed方法。在该方法中，将根据用户输入更新CarModel对象，然后在Controller类中,调用CarModel中的notifyObservers方法（此处为了节省代码量，在CarModel做了其他的处理，其效果是一样的）。而在notifyObservers方法中，则直接调用了SerachView和BitView中的update方法，实现了自动对被拍卖车的图片、文字信息以及拍卖价格的显示。

Controller类

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;public class Controller implements ActionListener{private final CarGUI cg;private final CarModel cm;private int preprice = 0;private int preprice1 = 0;private int preprice2 = 0;private int preprice3 = 0;public Controller(CarGUI cg, CarModel cm) {this.cg = cg;this.cm = cm;}@Overridepublic void actionPerformed(ActionEvent e) {if (e.getActionCommand().equals("Search")) {String text3 = cg.getCarName();String text=" Bit price for each car will be shown here";switch (text3) {case "Honda Accord-2005":cm.setImage("images\\Honda Accord-2005.jpg");cg.setData(cm.carSelected);cg.showPrice(text);break;case "Honda Civic-2006":cm.setImage("images\\Honda Civic-2006.jpg");cg.setData(cm.car2Selected);cg.showPrice(text);break;case "Toyota Camry-2003":cm.setImage("images\\Toyota Camry-2003.jpg");cg.setData(cm.car3Selected);cg.showPrice(text);break;case "Toyota Corolla-2002":cm.setImage("images\\Toyota Corolla-2002.jpg");cg.setData(cm.car4Selected);cg.showPrice(text);break;}}if (e.getActionCommand().equals("Bit")) {String text = cg.getBitPrice();String text2 = cg.getCarName();String text4=" Bit price for "+ text2 + " : "+ " illegal bit price ";if (text2.equals("Honda Accord-2005")){if(Integer.parseInt(text) > preprice){preprice = Integer.parseInt(text);cm.setImage("images\\Honda Accord-2005.jpg");cg.setData(cm.carSelected);cm.setCarName(text2);cm.setBitPrice(text);}else {cg.showPrice(text4);JOptionPane.showMessageDialog(null,"竞拍价格比上次低!","提示",JOptionPane.WARNING_MESSAGE);}}if (text2.equals("Honda Civic-2006")){if(Integer.parseInt(text) > preprice1){preprice1 = Integer.parseInt(text);cm.setImage("images\\Honda Civic-2006.jpg");cg.setData(cm.car2Selected);cm.setCarName(text2);cm.setBitPrice(text);}else {cg.showPrice(text4);JOptionPane.showMessageDialog(null,"竞拍价格比上次低!","提示",JOptionPane.WARNING_MESSAGE);}}if (text2.equals("Toyota Camry-2003")){if(Integer.parseInt(text) > preprice2){preprice2 = Integer.parseInt(text);cm.setImage("images\\Toyota Camry-2003.jpg");cg.setData(cm.car3Selected);cm.setCarName(text2);cm.setBitPrice(text);}else {cg.showPrice(text4);JOptionPane.showMessageDialog(null,"竞拍价格比上次低!","提示",JOptionPane.WARNING_MESSAGE);}}if (text2.equals("Toyota Corolla-2002")){if(Integer.parseInt(text) > preprice3){preprice3 = Integer.parseInt(text);cm.setImage("images\\Toyota Corolla-2002.jpg");cg.setData(cm.car4Selected);cm.setCarName(text2);cm.setBitPrice(text);}else {cg.showPrice(text4);JOptionPane.showMessageDialog(null,"竞拍价格比上次低!","提示",JOptionPane.WARNING_MESSAGE);}}}if (e.getActionCommand().equals("Exit")) {System.exit(0);}}
}