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
}
}
