mvc模式介紹

本文要實現的Java應用程式是當用戶在圖形化使用者介面輸入一個球體的半徑時，程式將顯示該球體的體積與表面積。

SphereWindow類為Controller角色。

package newspherepro; import java.util.Observable; /** * * <p>Title: The Model part of Application</p> * <p>Description: This class represents an observable object, * or "data" in the model-view paradigm. It can be subclassed to represent * an object that the application wants to have observed. </p> * <p>Copyright: Copyright (c) 2005</p> * @author Smart Lee * @version 1.1 */ public class Sphere extends Observable { // 定義球體半徑 private double sphereRadius; // 定義球體體積 private double sphereVolume; // 定義球體表面積 private double sphereSuArea; /** * 根據球體半徑值設定球體三個屬性值 * @param sphereRadius double */ public void setRadius (double sphereRadius) { this.sphereRadius = sphereRadius; this.sphereVolume = 4 * Math.PI * Math.pow(sphereRadius, 3) / 3; this.sphereSuArea = 4 * Math.PI * Math.pow(sphereRadius, 2); //變化後通知檢視做相應變化 setChanged(); notifyObservers(); } /** * 根據球體體積值設定球體三個屬性值 * @param sphereVolume double */ public void setVolume(double sphereVolume) { this.sphereVolume = sphereVolume; this.sphereRadius = Math.pow(3 * sphereVolume / (4 * Math.PI), 1 / 3.0); this.sphereSuArea = 3 * sphereVolume / sphereRadius; setChanged(); notifyObservers(); } /** * 根據球體表面積值設定球體三個屬性值 * @param sphereSuArea double */ public void setSuArea(double sphereSuArea) { this.sphereSuArea = sphereSuArea; this.sphereRadius = Math.pow(sphereSuArea / (4 * Math.PI), 1 / 2.0); this.sphereVolume = sphereSuArea * sphereRadius /3; setChanged(); notifyObservers(); } /** * 取得球體半徑值 * @return double */ public double getRadius() { return sphereRadius; } /** * 取得球體體積值 * @return double */ public double getVolume() { return sphereVolume; } /** * 取得球體表面積值 * @return double */ public double getSuArea() { return sphereSuArea; } }

TextView.java

package newspherepro; import java.util.Observer; import java.util.Observable; import java.text.NumberFormat; import javax.swing.*; import java.awt.*; import java.awt.event.*; /** * * <p>Title: The View part of Application </p> * <p>Description: A class can implement the Observer interface when it wants to * be informed of changes in observable objects. </p> * <p>Copyright: Copyright (c) 2005</p> * @author Smart Lee * @version 1.1 */ public class TextView extends JPanel implements Observer { GridBagLayout gridBagLayout1 = new GridBagLayout(); private boolean textBlankFlag = true; JLabel radiusLab = new JLabel(); JLabel volumeLab = new JLabel(); JLabel suAreaLab = new JLabel(); JTextField radiusTextField = new JTextField(); JTextField volumeTextField = new JTextField(); JTextField surfAreaTextField = new JTextField(); public TextView() { try { jbInit(); } catch(Exception e) { e.printStackTrace(); } } //實現介面的方法 public void update (Observable o, Object arg) { NumberFormat nf = NumberFormat.getInstance(); Sphere balloon = (Sphere) o; if(textBlankFlag) { radiusTextField.setText(""); volumeTextField.setText(""); surfAreaTextField.setText(""); textBlankFlag = false; } else { radiusTextField.setText(nf.format(balloon.getRadius())); volumeTextField.setText(nf.format(balloon.getVolume())); surfAreaTextField.setText(nf.format(balloon.getSuArea())); } } private void jbInit() throws Exception { radiusLab.setFont(new java.awt.Font("Dialog", 0, 14)); radiusLab.setText(" Radius ="); this.setBackground(Color.lightGray); this.setForeground(Color.black); this.setLayout(gridBagLayout1); volumeLab.setFont(new java.awt.Font("Dialog", 0, 14)); volumeLab.setText(" Volume ="); suAreaLab.setFont(new java.awt.Font("Dialog", 0, 14)); suAreaLab.setText(" Surface area ="); radiusTextField.setFont(new java.awt.Font("Dialog", 0, 14)); radiusTextField.setText(""); volumeTextField.setFont(new java.awt.Font("Dialog", 0, 14)); volumeTextField.setText(""); surfAreaTextField.setFont(new java.awt.Font("Dialog", 0, 14)); surfAreaTextField.addActionListener(new TextView_surfAreaTextField_actionAdapter(this)); this.add(radiusLab, new GridBagConstraints(0, 0, 1, 2, 0.0, 0.0 ,GridBagConstraints.NORTH, GridBagConstraints.NONE, new Insets(-1, 0, 0, 0), 86, 10)); this.add(volumeLab, new GridBagConstraints(0, 2, 1, 1, 0.0, 0.0 ,GridBagConstraints.WEST, GridBagConstraints.NONE, new Insets(0, 0, 0, 0), 0, 0)); this.add(suAreaLab, new GridBagConstraints(0, 3, 1, 1, 0.0, 0.0 ,GridBagConstraints.WEST, GridBagConstraints.NONE, new Insets(0, 0, 0, 0), 0, 0)); this.add(radiusTextField, new GridBagConstraints(1, 0, 1, 1, 0.0, 0.0 ,GridBagConstraints.WEST, GridBagConstraints.NONE, new Insets(0, -19, 0, 19), 147, 1)); this.add(volumeTextField, new GridBagConstraints(1, 1, 1, 2, 0.0, 0.0 ,GridBagConstraints.WEST, GridBagConstraints.NONE, new Insets(0, -19, 0, 19), 147, 3)); this.add(surfAreaTextField, new GridBagConstraints(1, 3, 1, 1, 0.0, 0.0 ,GridBagConstraints.WEST, GridBagConstraints.NONE, new Insets(0, -19, 0, 19), 147, 4)); } void surfAreaTextField_actionPerformed(ActionEvent e) { } } class TextView_surfAreaTextField_actionAdapter implements java.awt.event.ActionListener { TextView adaptee; TextView_surfAreaTextField_actionAdapter(TextView adaptee) { this.adaptee = adaptee; } public void actionPerformed(ActionEvent e) { adaptee.surfAreaTextField_actionPerformed(e); } }

SphereWindow類作為Controller，它主要新建Model與View，將view與Model相關聯，並處理事件

package newspherepro; import javax.swing.*; import java.awt.event.*; /** * <p>Title: SphereWindow</p> * <p>Description: The Controller part of the model-view paradigm</p> * <p>Copyright: Copyright (c) 2005</p> * @author Smart Lee * @version 1.1 */ public class SphereWindow extends SphereFrame implements ActionListener, MouseListener, MouseMotionListener{ // 建立檢視一 TextView tView = new TextView(); // 建立檢視二 GraphicsView gView = new GraphicsView(); // 建立模型 Sphere model = new Sphere(); //Construct the application public SphereWindow() { try { jbInit(); } catch(Exception e) { e.printStackTrace(); } } //Main method public static void main(String[] args) { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch(Exception e) { e.printStackTrace(); } new SphereWindow(); } private void jbInit() throws Exception { // 新增檢視 contentPane.add(tView); contentPane.add(gView); this.setVisible(true); // 建立模型與檢視一的關聯 model.addObserver(tView); tView.update(model, null); // 建立模型與檢視二的關聯 model.addObserver(gView); gView.update(model, null); // 為檢視一各控制元件新增事件監聽器 tView.radiusTextField.addActionListener(this); tView.volumeTextField.addActionListener(this); tView.surfAreaTextField.addActionListener(this); // 為檢視二新增滑鼠事件 gView.addMouseListener(this); gView.addMouseMotionListener(this); } public void actionPerformed(ActionEvent e) { if (e.getSource() == tView.radiusTextField) { JTextField jtf = (JTextField)e.getSource(); // 捕獲異常字元 try { double radius = Double.parseDouble(jtf.getText()); // 更改模型資料 model.setRadius(radius); } catch (Exception ex) { JOptionPane.showMessageDialog(null,"illegal character!"); } // 呼叫檢視二的繪圖方法以更新檢視 gView.repaint(); } if (e.getSource() == tView.volumeTextField) { JTextField jtf = tView.volumeTextField; try { double volume = Double.parseDouble(jtf.getText()); model.setVolume(volume); } catch(Exception ex) { JOptionPane.showMessageDialog(null,"illegal character!"); } gView.repaint(); } if (e.getSource() == tView.surfAreaTextField) { JTextField jtf = (JTextField)e.getSource(); try { double surfArea = Double.parseDouble(jtf.getText()); model.setSuArea(surfArea); } catch(Exception ex) { JOptionPane.showMessageDialog(null,"illegal character!"); } gView.repaint(); } } public void mousePressed(MouseEvent e) { int X = gView.getWidth() / 2; int Y = gView.getHeight() / 2; gView.bShowDim = true; // 控制是否顯示點座標 gView.x = e.getX(); gView.y = e.getY(); // 圓心座標(X, Y) gView.radius = pointDistance(gView.x, gView.y, X, Y); // 更改資料模型 model.setRadius(gView.radius); gView.repaint(); } public void mouseReleased(MouseEvent e) { // 滑鼠離開時不再顯示點座標 gView.bShowDim = false; gView.repaint(); } public void mouseEntered(MouseEvent e) { } public void mouseExited(MouseEvent e) { } public void mouseClicked(MouseEvent e) { } public void mouseMoved(MouseEvent e) { } public void mouseDragged(MouseEvent e) { int X = gView.getWidth() / 2; int Y = gView.getHeight() / 2; gView.bShowDim = true; gView.x = e.getX(); gView.y = e.getY(); gView.radius = pointDistance(gView.x, gView.y, X, Y); model.setRadius(gView.radius); gView.repaint(); } /** * 求兩點距離 * @param x1 double 點1的橫座標 * @param y1 double 點1的縱座標 * @param x2 double 點2的橫座標 * @param y2 double 點2的縱座標 * @return double */ protected double pointDistance(double x1, double y1, double x2, double y2) { return Math.pow(((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)), 1/2.0); } }  

GraphicsView.java

 package newspherepro; import java.util.Observer; import java.util.Observable; import java.awt.Graphics; import java.awt.Canvas; /** * * <p>Title: The View part of Application </p> * <p>Description: A class can implement the Observer interface when it wants to * be informed of changes in observable objects. </p> * <p>Copyright: Copyright (c) 2005</p> * @author Smart Lee * @version 1.1 */ public class GraphicsView extends Canvas implements Observer { // 定義滑鼠座標 int x, y; // 定義球半徑 double radius; // 控制點座標是否顯示 boolean bShowDim; //實現介面的方法 public void update(Observable o, Object arg) { Sphere balloon = (Sphere) o; radius = balloon.getRadius(); } // 繪球體 public void paint(Graphics g) { int d = (int) radius * 2; int X = this.getWidth(); int Y = this.getHeight(); // 注意不能在全域性變數裡設值！ g.drawOval( (X - d) / 2, (Y - d) / 2, d, d); g.drawOval( (X - d) / 2, Y / 2 - d / 8, d, d / 4); g.drawOval(X / 2 - d / 8, (Y - d) / 2, d / 4, d); // 顯示滑鼠座標 if(bShowDim) { g.drawString("(" + x + ", " + y + ")", x, y); } } }  

SphereFrame.java

package newspherepro; import java.awt.*; import java.awt.event.*; import javax.swing.*; /** * <p>Title: SphereFrame</p> * <p>Description: configure the basic info of JFrame</p> * <p>Copyright: Copyright (c) 2005</p> * @author Smart Lee * @version 1.1 */ public class SphereFrame extends JFrame { boolean packFrame = false; JPanel contentPane; GridLayout borderLayout1 = new GridLayout(1, 2); //Construct the frame public SphereFrame() { enableEvents(AWTEvent.WINDOW_EVENT_MASK); try { jbInit(); } catch(Exception e) { e.printStackTrace(); } } //Component initialization private void jbInit() throws Exception { //Validate frames that have preset sizes //Pack frames that have useful preferred size info, e.g. from their layout if (packFrame) { this.pack(); } else { this.validate(); } //Center the window Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); Dimension frameSize = this.getSize(); if (frameSize.height > screenSize.height) { frameSize.height = screenSize.height; } if (frameSize.width > screenSize.width) { frameSize.width = screenSize.width; } this.setSize(600,300); // 使視窗居中 this.setLocationRelativeTo(null); contentPane = (JPanel) this.getContentPane(); contentPane.setLayout(borderLayout1); this.getContentPane().setBackground(SystemColor.controlLtHighlight); this.setTitle("Spheres: volume and surface area"); } //Overridden so we can exit when window is closed protected void processWindowEvent(WindowEvent e) { super.processWindowEvent(e); if (e.getID() == WindowEvent.WINDOW_CLOSING) { System.exit(0); } } }