#软件设计模式#桥接模式#小黑的学习笔记

bridge pattren: 个人简单理解

        当出现两个角色，且它们之间存在一定的制约关系，纬度高的角色含有对维度低角色的引用，这个引用就相当于桥梁。这样避免了它们之间出现继承关系，使得纬度低的角色不用继承或实现纬度高的角色，这样一来两个类都可以独立的变化而不受到影响。当纬度高的角色需要通过纬度低的角色实现某种业务时，就可以通过桥梁来访问即可，举个栗子：如图：战区司令部对军队有指挥权，战区司令部含有类型为军队的属性，相当于有了兵权，打仗时直接调就行。而战区司令部又包括中部战区，东部战区，西部战区等，添加的时候直接实现战区司令部接口就行，同时军队又分海军，空军，陆军，甚至可以细分为军，师，旅，团，营，连也只需要实现军队接口就行。这样他们都可以各自独立的变化，实现解耦合，灵活度更高。后期添加个特种兵直接实现军队接口，而不用和战区司令部有联系。

(下面的可以不用看了)实验报告：

将桥接模式的教材P93例子自动茶水销售机做修改。由两个维度扩展到三个维度

在已有TeaSize ,TeaKind.上再加一个维度TeaType，实现加糖维度，比如加红糖或黑糖.

 修改后：

teaSize:

public interface TeaSize {
   public abstract float getPrice();

}
//中杯
public class MediumCup implements TeaSize{
   //含有对TeaKind 和TeaType的引用
   private TeaKind tk;
   private TeaType tt;

   public MediumCup(TeaKind tKind,TeaType tType){
   	  tk = tKind;
      tt=tType ;
   }
   public float getPrice(){
      float teaPrice = tk.price()+tt.addSugar();
      return teaPrice;
   }
}
//大杯
public class SuperCup implements TeaSize{
//含有对TeaKind 和TeaType的引用
   private TeaKind tk;
   private TeaType tt ;
   public SuperCup(TeaKind tKind,TeaType tType){
	  tk = tKind;
      tt = tType ;
   }

   public float getPrice(){
      float teaPrice = 1.5f * tk.price()+tt.addSugar();
      return teaPrice;
   }
}

TeaKind: 

public interface TeaKind {
   public abstract float price();
}

//绿茶
public class GreenTea implements TeaKind{
   private final float PRICE = 2.0f;
   public float price(){
      return PRICE;
   }
}
//红茶
public class RedTea implements TeaKind{

   private final float PRICE = 3.0f;

   public float price(){
      return PRICE;
   }
}

 加糖：

public interface TeaType {
    public abstract float addSugar();
}
//不加糖
public class NoSugar implements TeaType {
    private final float PRICE = 0.0f;
    @Override
    public float addSugar() {
        return PRICE;
    }
}
//红糖
public class redSugar implements TeaType{
    private final float PRICE=0.5f;
    @Override
    public float addSugar() {
        return PRICE ;
    }
}
//黑糖
public class blackSugar implements TeaType{
    private final float PRICE=0.7f ;
    @Override
    public float addSugar() {
        return PRICE;
    }
}

GUI :

//GUI
public class ClientTeaGUI extends JFrame {
    public static final String FINDPRICE = "Find Price";
    public static final String EXIT = "Exit";
    public static final String SUPERCUP = "Super Cup";
    public static final String MEDIUMCUP = "Medium Cup";
    public static final String REDTEA = "Red Tea";
    public static final String GREENTEA = "Green Tea";
    public static final String REDSUGAR = "Red Sugar";
    public static final String BLACKTEA = "Black Sugar";
    public static final String NOSUGAR ="No Sugar" ;

    private JLabel lblCupSize, lblTeaKind,lblTeaType, lblTeaPrice, lblChosenTeaPrice;
    private JComboBox cmbCupSize, cmbTeaKind,cmbTeaType;
    private JButton findBtn, exitButton;

    public ClientTeaGUI() {
        super(" Bridge Pattern: Tea Seller Machine ");

        cmbCupSize = new JComboBox();
        cmbCupSize.addItem(SUPERCUP);
        cmbCupSize.addItem(MEDIUMCUP);

        cmbTeaKind = new JComboBox();
        cmbTeaKind.addItem(REDTEA);
        cmbTeaKind.addItem(GREENTEA);

        cmbTeaType=new JComboBox() ;
        cmbTeaType.addItem(BLACKTEA);
        cmbTeaType.addItem(REDSUGAR);
        cmbTeaType.addItem(NOSUGAR);

        lblCupSize = new JLabel("Choose Cup Size");
        lblTeaKind = new JLabel("Choose Tea Kind");
        lblTeaType = new JLabel("Choose To Add Sugar");
        lblTeaPrice = new JLabel("Tea Price:");
        lblChosenTeaPrice = new JLabel("Tea Price will be shown here");

        //Create the open button
        findBtn = new JButton(FINDPRICE);
        findBtn.setMnemonic(KeyEvent.VK_V);
        exitButton = new JButton(EXIT);
        exitButton.setMnemonic(KeyEvent.VK_X);
        ButtonListener objButtonListener = new ButtonListener();

        findBtn.addActionListener(objButtonListener);
        exitButton.addActionListener(new ButtonListener());

        JPanel buttonPanel = new JPanel();
        buttonPanel.add(findBtn);
        buttonPanel.add(exitButton);

        JPanel UIPanel = new JPanel();

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

        UIPanel.add(lblCupSize);
        UIPanel.add(cmbCupSize);

        UIPanel.add(lblTeaKind);
        UIPanel.add(cmbTeaKind);

        UIPanel.add(lblTeaType) ;
        UIPanel.add(cmbTeaType) ;

        UIPanel.add(lblTeaPrice);
        UIPanel.add(lblChosenTeaPrice);
        UIPanel.add(buttonPanel);

        gbc.insets.top = 5;
        gbc.insets.bottom = 5;
        gbc.insets.left = 5;
        gbc.insets.right = 10;
        gbc.anchor = GridBagConstraints.WEST;

        gbc.gridx = 0;
        gbc.gridy = 0;

        gridbag.setConstraints(lblCupSize, gbc);
        gbc.gridx = 1;
        gbc.gridy = 0;
        gridbag.setConstraints(cmbCupSize, gbc);
        gbc.gridx = 0;
        gbc.gridy = 1;


        gridbag.setConstraints(lblTeaKind, gbc);
        gbc.gridx = 1;
        gbc.gridy = 1;
        gridbag.setConstraints(cmbTeaKind, gbc);
        gbc.gridx = 0;
        gbc.gridy = 2;


        gridbag.setConstraints(lblTeaPrice, gbc);
        gbc.gridx = 1;
        gbc.gridy = 2;
        gridbag.setConstraints(lblChosenTeaPrice, gbc);

        gbc.insets.left = 2;
        gbc.insets.right = 2;
        gbc.insets.top = 40;

        gbc.gridx = 1;
        gbc.gridy = 5;
        gridbag.setConstraints(buttonPanel, gbc);

        Container contentPane = getContentPane();
        contentPane.add(UIPanel, BorderLayout.CENTER);

        try {

            UIManager.setLookAndFeel(new WindowsLookAndFeel());
            SwingUtilities.updateComponentTreeUI(
                    ClientTeaGUI.this);
        } catch (Exception ex) {
//            System.out.println(ex);
            throw new RuntimeException(ex);
        }
    }

    public static void main(String[] args) {
        JFrame frame = new ClientTeaGUI();
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        frame.setSize(1080, 500);
        frame.setVisible(true);
    }

    public String getTeaSize() {
        return (String) cmbCupSize.getSelectedItem();
    }

    public String getTeaKind() {
        return (String) cmbTeaKind.getSelectedItem();
    }

    public String getTeaType() {
        return (String) cmbTeaType.getSelectedItem();
    }


    class ButtonListener implements ActionListener {

        TeaKind tKind;
        TeaSize tSize;
        TeaType tType;

        public void actionPerformed(ActionEvent e) {
            if (e.getActionCommand().equals(EXIT)) {
                System.exit(1);
            }
            if (e.getActionCommand().equals(FINDPRICE)) {

                String size = getTeaSize();
                String kind = getTeaKind();
                String Type = getTeaType();

                //Create a customer object
                if (kind.compareTo(GREENTEA) == 0)
                    tKind = new GreenTea();
                if (kind.compareTo(REDTEA) == 0)
                    tKind = new RedTea();

                if (size.compareTo(SUPERCUP) == 0)
                    tSize = new SuperCup(tKind,tType);
                if (size.compareTo(MEDIUMCUP) == 0)
                    tSize = new MediumCup(tKind,tType);

                if(Type.compareTo(REDSUGAR)==0)
                    tType =new redSugar();
                if(Type.compareTo(BLACKTEA)==0)
                    tType =new blackSugar();
                if(Type.compareTo(NOSUGAR)==0)
                    tType =new NoSugar();


                float price = tSize.getPrice();

                lblChosenTeaPrice.setText("" + price + "  dollars");
            }
        }
    }
}

输入输出:

 

类图:

 时序图: