设计模式NO.3

设计模式NO.3

本次博客内容为第三次设计模式的练习。根据老师的要求完成下列题目：

题目1

某商品管理系统的商品名称存储在一个字符串数组中，现需要自定义一个双向迭代器（MyIterator）实现对该商品名称数组的双向（向前和向后）遍历。使用Iterator模式来设计。

类图设计如下：



代码实现如下：

a.Iterator接口

public interface Iterator {
	public boolean hasNext();
	public boolean hasFront();
	public String next();
	public String front();
	public void setPositionOrder();
	public void setPositionReverse();

}

b.具体Iterator类

public class MyIterator implements Iterator{

	private Aggregate m_agg;
	private int current;
	private int size;

	public MyIterator(Aggregate m_agg)
	{
		current=0;
		size = m_agg.getLength();
		this.m_agg=m_agg;
	}
	@Override
	public boolean hasNext() {
		if(current<size)
			return true;

		else
			return false;
	}

	@Override
	public boolean hasFront() {
		if(current>=0)
			return true;
		else
			return false;
	}
	@Override
	public String next() {

		return m_agg.getName(current++);
	}
	@Override
	public String front() {

		return m_agg.getName(current--);
	}

	@Override
	public void setPositionOrder() {
		current = 0;

	}
	@Override
	public void setPositionReverse() {
		current = size-1;

	}

}

c.Aggregate接口

public interface Aggregate {
	public Iterator CreateIterator();
	public int getLength();
	public String getName(int position);
	public void addName(String name);

}

d.具体物品类

public class GoodList implements Aggregate{
	private String names[];
	private int num;

	public GoodList(int MaxNum)
	{
		num=0;
		this.names = new String[MaxNum];
	}
	public int getLength()
	{
		return num;
	}
	public String getName(int position)
	{
			return names[position];
	}
	public void addName(String name)
	{
		names[num++]=name;
	}

	@Override
	public Iterator CreateIterator() {
		return new MyIterator(this);
	}

}

e.测试代码

public class client {
	public static void main(String[] args) {
		Aggregate agg = new GoodList(100);
		agg.addName("洗手液");
		agg.addName("洗衣液");
		agg.addName("牙膏");
		agg.addName("洗发露");
		Iterator it = agg.CreateIterator();

		Orderview(it);
		ReverseView(it);
	}
	private static void Orderview(Iterator it)
	{
		it.setPositionOrder();
		while(it.hasNext())
			System.out.println(it.next());
	}
	private static void ReverseView(Iterator it)
	{
		it.setPositionReverse();
		while(it.hasFront())
			System.out.println(it.front());
	}

}

题目2

某公司欲开发一个基于Windows平台的公告板系统，系统提供主菜单（Menu）其中有菜单项（MenuItem）。通过Menu类的addMenuItem()方法增加菜单项。菜单项的打开方法是click(）,每个菜单项包含一个抽象命令类，具体命令类包括OpenCommand()、CreateCommand()、EditCommand()等，命令类具有一个execute()方法，用于调用公告板系统界面类（BoardScreen()）的open()、create()、edit()）等方法。使用Command模式来设计。

类图设计如下：



代码实现如下：

a.抽象命令类

public abstract class Command {
	protected BoardScreen bs;

	public Command(BoardScreen bs)
	{
		this.bs = bs;
	}
	public abstract void execute();

}

b.CreateCommand类

public class CreateCommand extends Command{

	public CreateCommand(BoardScreen bs) {
		super(bs);

	}

	@Override
	public void execute() {
		bs.create();

	}

}

c.OpenCommand类

public class OpenCommand extends Command{

	public OpenCommand(BoardScreen bs) {
		super(bs);
	}

	@Override
	public void execute() {
		bs.open();
	}

}

d.EditCommand类

public class EditCommand extends Command{

	public EditCommand(BoardScreen bs) {
		super(bs);
	}

	@Override
	public void execute() {
		bs.edit();

	}

}

e.BoardScreen类

public class BoardScreen {

	public void open()
	{
		System.out.println("BoardScreen is opening!");
	}
	public void create()
	{
		System.out.println("BoardScreen is creating!");
	}

	public void edit()
	{
		System.out.println("BoardScreen is editing!");
	}
}

f.Menu类

public class Menu {

	private ArrayList<MenuItem> items = new ArrayList<MenuItem>();

	public void addItem(MenuItem item)
	{
		items.add(item);
	}

	public void clickItem(int index)
	{
		items.get(index).click();
	}

}

g.MenuItem类

public class MenuItem {
	private Command com;

	public MenuItem(Command com)
	{
		this.com=com;
	}
	public void click()
	{
		com.execute();
	}

}

h.测试类

public class client {
	public static void main(String[] args) {
		BoardScreen bs = new BoardScreen();
		Menu menus = new Menu();

		Command command = new CreateCommand(bs);
		menus.addItem(new MenuItem(command));

		command = new OpenCommand(bs);
		menus.addItem(new MenuItem(command));

		command = new EditCommand(bs);
		menus.addItem(new MenuItem(command));

		menus.clickItem(0);//BoardScreen is creating!
		menus.clickItem(1);//BoardScreen is opening!
		menus.clickItem(2);//BoardScreen is editing!
	}

}

题目3

某论坛系统欲增加一个虚拟聊天室，允许论坛会员通过该聊天室进行信息交流，普通会员（CommonMember）可以给其他会员发送文本信息，钻石会员（DiamondMember）可以给其他会员发送文本和图片信息。该聊天室可以对不雅字符进行过滤，如“TMD”等字符，还可以对发送图片大小进行控制。使用Mediator模式来设计。

类图设计如下：



代码设计如下：

a.抽象Member类

public abstract class Member {
	protected ChatRoom cr;
	protected String name;

	public Member(String name)
	{
		this.name = name;
	}

	public abstract void setChatRoom(ChatRoom cr);
	public abstract void sendPic(String pic);
	public abstract void sendText(String text);
}

b.抽象聊天室类

public abstract class ChatRoom {
	public abstract void sendPic(String pic);
	public abstract void sendText(String text);

}

c.CommonMember类

public class CommonMember extends Member{

	public CommonMember(String name) {
		super(name);
	}

	@Override
	public void setChatRoom(ChatRoom cr) {
		this.cr=cr;

	}

	@Override
	public void sendPic(String pic) {
		System.out.println("only DiamonMember can send picture!" );

	}

	@Override
	public void sendText(String text) {
		System.out.print("CommonMember ["+name+"] says: ");
		cr.sendText(text);

	}

}

d.DiamondMember类

public class DiamondMember extends Member{

	public DiamondMember(String name) {
		super(name);
	}

	@Override
	public void setChatRoom(ChatRoom cr) {
		this.cr=cr;

	}

	@Override
	public void sendPic(String pic) {
		System.out.print("DiamondMember ["+name+"] send a picture: ");
		cr.sendPic(pic);

	}

	@Override
	public void sendText(String text) {
		System.out.print("DiamondMember ["+name+"] says: ");
		cr.sendText(text);
	}

}

e.RealChatRoom具体类

public class RealChatRoom extends ChatRoom{

	@Override
	public void sendPic(String pic) {
		if(PicCheck(pic))
		{
			System.out.println(pic);
		}
		else
			System.out.println("the size of picture is too large");

	}

	@Override
	public void sendText(String text) {
		System.out.println(TextFilter(text));

	}

	private boolean PicCheck(String Pic)
	{
		if(Pic.length()>9)
			return false;
		else
			return true;
	}

	private String TextFilter(String text)
	{
		return text.replaceAll("[Tt][Mm][Dd]", "***");
	}

}

f.测试类

public class client {
	public static void main(String[] args) {
		ChatRoom cr = new RealChatRoom();

		Member m1 = new CommonMember("Jack");
		Member m2 = new DiamondMember("Will");

		m1.setChatRoom(cr);
		m2.setChatRoom(cr);

		m1.sendText("tmd,NTMD,blablabla....");//CommonMember [Jack] says: ***,N***,blablabla....
		m1.sendPic("gogogogogogogogog");//only DiamonMember can send picture!

		m2.sendText("tmd,NTMD,blablabla....");//DiamondMember [Will] says: ***,N***,blablabla....
		m2.sendPic("good");//DiamondMember [Will] send a picture: good
		m2.sendPic("goodgoodgoodgoodgoodgood");//DiamondMember [Will] send a picture: the size of picture is too large
	}

}

题目4

设计一个网上书店，对系统中所有的计算机类图书（ComputerBook）每本都有10%的折扣，语言类图书（LanguageBook）每本都有2元的折扣，小说类图书（NovelBook）每100元有15元的折扣。使用Strategy模式来设计。

类图设计如下：



代码设计如下：

a.抽象Discount类

public abstract class Discount {

	public abstract double discount(double price);
}

b.ComputerDiscount类

public class ComputerDiscount extends Discount{

	@Override
	public double discount(double price) {
		return price*0.9;
	}

}

c.LanguageDiscount类

public class LanguageDiscount extends Discount{

	@Override
	public double discount(double price) {
		return price-2;
	}

}

d.NovelDiscount类

public class NovelDiscount extends Discount{

	@Override
	public double discount(double price) {
		return price-(price/100)*15;
	}
}

e.Book类

public class Book {
	private double price;
	private Discount dis;
	public Book(Discount dis)
	{
		this.dis=dis;
	}

	public void setDiscount(Discount dis)
	{
		this.dis=dis;
	}
	public void setPrice(double price)
	{
		this.price = price;
	}
	public double getPrice()
	{
		return dis.discount(price);
	}
}

f.测试类

public class client {
	public static void main(String[] args) {
		Book computer = new Book(new ComputerDiscount());
		computer.setPrice(100.0);

		Book language = new Book(new LanguageDiscount());
		language.setPrice(100.0);

		Book novel = new Book(new NovelDiscount());
		novel.setPrice(100.0);

		System.out.println(computer.getPrice());//90.0
		System.out.println(language.getPrice());//98.0
		System.out.println(novel.getPrice());//85.0

	}

}