设计模式之状态模式浅析

   

/** *  * 状态模式： *   允许对象在内部状态改变时改变他的行为，对象看起来好像修改了他的类 *    * 封装基于状态的行为，并将行为委托到当前状态  * 通过把状态封装进一个类，把以后要做的事情局部化了 *  * 策略模式和状态模式有相同的类图，但是彼此的意图不同 *  * State接口定义了一个所有具体状态的共同接口 * Context是一个类，他可以拥有一些内部状态   糖果机就是Context *    * 示例 *   糖果机模型 *    5个状态：没有5块钱状态、有5块钱状态、赢家模式状态、出售糖果状态  、糖果售罄状态 *    4个动作：投5块钱、退5块钱、按钮售出按钮、售出糖果 *     *  * @author Administrator * */

状态接口 封装行为

package com.undergrowth.state;/** *  * 状态模式： *   允许对象在内部状态改变时改变他的行为，对象看起来好像修改了他的类 *    * 封装基于状态的行为，并将行为委托到当前状态  * 通过把状态封装进一个类，把以后要做的事情局部化了 *  * 策略模式和状态模式有相同的类图，但是彼此的意图不同 *  * State接口定义了一个所有具体状态的共同接口 * Context是一个类，他可以拥有一些内部状态   糖果机就是Context *    * 示例 *   糖果机模型 *    5个状态：没有5块钱状态、有5块钱状态、赢家模式状态、出售糖果状态  、糖果售罄状态 *    4个动作：投5块钱、退5块钱、按钮售出按钮、售出糖果 *     *  * @author Administrator * */public interface State {public void insertCoins();public void coinsHopper();public void pressSold();public void soldCandy();}

没有5块钱状态

package com.undergrowth.state;/** * 没有5块钱的状态 * @author Administrator * */public class NoMoneyState implements State {GumballMachine gumballMachine;public NoMoneyState(GumballMachine gumballMachine) {super();this.gumballMachine = gumballMachine;}@Overridepublic void insertCoins() {// TODO Auto-generated method stubSystem.out.println("你投了5块钱");gumballMachine.setState(gumballMachine.getHasMoneyState());}@Overridepublic void coinsHopper() {// TODO Auto-generated method stubSystem.out.println("你没有投钱，甭想退钱");}@Overridepublic void pressSold() {// TODO Auto-generated method stubSystem.out.println("你没有投钱，甭想买糖果");}@Overridepublic void soldCandy() {// TODO Auto-generated method stubSystem.out.println("你没有投钱，甭想买糖果");}}

有5块钱状态

package com.undergrowth.state;import java.util.Random;public class HasMoneyState implements State {GumballMachine gumballMachine;// 记录是够进入玩家模式Random randomWinner = new Random(System.currentTimeMillis());public HasMoneyState(GumballMachine gumballMachine) {// TODO Auto-generated constructor stubthis.gumballMachine = gumballMachine;}@Overridepublic void insertCoins() {// TODO Auto-generated method stubSystem.out.println("已经投过币了，不要在投币了");}@Overridepublic void coinsHopper() {// TODO Auto-generated method stubSystem.out.println("退币成功");gumballMachine.setState(gumballMachine.getNoMoneyState());}@Overridepublic void pressSold() {// TODO Auto-generated method stubSystem.out.println("你按下售出糖果按钮，即将售出糖果");int winner = randomWinner.nextInt(10);//十分之一机会 进入赢家模式if (winner == 0 && gumballMachine.getCount() > 1) {gumballMachine.setState(gumballMachine.getWinnerState());} else {gumballMachine.setState(gumballMachine.getSoldState());}}@Overridepublic void soldCandy() {// TODO Auto-generated method stubSystem.out.println("你没有操作，甭想售出糖果");}}

售出糖果状态

package com.undergrowth.state;public class SoldState implements State {GumballMachine gumballMachine;public SoldState(GumballMachine gumballMachine) {// TODO Auto-generated constructor stubthis.gumballMachine=gumballMachine;}@Overridepublic void insertCoins() {// TODO Auto-generated method stubSystem.out.println("正在售出糖果，不要投币");}@Overridepublic void coinsHopper() {// TODO Auto-generated method stubSystem.out.println("正在售出糖果，不要退币");}@Overridepublic void pressSold() {// TODO Auto-generated method stubSystem.out.println("正在售出糖果，不要再按下售出按钮了");}@Overridepublic void soldCandy() {// TODO Auto-generated method stubgumballMachine.releaseCandy();if(gumballMachine.getCount()>0){gumballMachine.setState(gumballMachine.getNoMoneyState());}else {System.out.println("没有糖果了，进入糖果售罄状态");gumballMachine.setState(gumballMachine.getSoldOutState());}}}

赢家模式状态

package com.undergrowth.state;public class WinnerState implements State {GumballMachine gumballMachine;public WinnerState(GumballMachine gumballMachine) {// TODO Auto-generated constructor stubthis.gumballMachine=gumballMachine;}@Overridepublic void insertCoins() {// TODO Auto-generated method stubSystem.out.println("正在售出糖果，不要投币");}@Overridepublic void coinsHopper() {// TODO Auto-generated method stubSystem.out.println("正在售出糖果，不要退币");}@Overridepublic void pressSold() {// TODO Auto-generated method stubSystem.out.println("正在售出糖果，不要再按下售出按钮了");}@Overridepublic void soldCandy() {// TODO Auto-generated method stubSystem.out.println("你进入了赢家模式，会获得两个糖果");gumballMachine.releaseCandy();if(gumballMachine.getCount()==0){System.out.println("没有糖果了，进入糖果售罄状态");gumballMachine.setState(gumballMachine.getSoldOutState());}else {gumballMachine.releaseCandy();if(gumballMachine.getCount()>0){gumballMachine.setState(gumballMachine.getNoMoneyState());}else {System.out.println("没有糖果了，进入糖果售罄状态");gumballMachine.setState(gumballMachine.getSoldOutState());}}}}

糖果售完状态

package com.undergrowth.state;public class SoldOutState implements State {GumballMachine gumballMachine;public SoldOutState(GumballMachine gumballMachine) {// TODO Auto-generated constructor stubthis.gumballMachine=gumballMachine;}@Overridepublic void insertCoins() {// TODO Auto-generated method stubSystem.out.println("没有糖果了，不要投币");}@Overridepublic void coinsHopper() {// TODO Auto-generated method stubSystem.out.println("没有糖果了，不要退币");}@Overridepublic void pressSold() {// TODO Auto-generated method stubSystem.out.println("没有糖果了，不要按下售出按钮");}@Overridepublic void soldCandy() {// TODO Auto-generated method stubSystem.out.println("没有糖果了");}}

糖果机 拥有一系列的状态  同时拥有当前状态

package com.undergrowth.state;/** * 糖果机器 *  * @author Administrator *  */public class GumballMachine {//状态切换在这5个状态之间State noMoneyState;State hasMoneyState;State soldState;State soldOutState;State winnerState;// 当前状态State state;//糖果剩余数int count;public GumballMachine(int numCandy) {noMoneyState = new NoMoneyState(this);hasMoneyState = new HasMoneyState(this);winnerState = new WinnerState(this);soldState = new SoldState(this);soldOutState = new SoldOutState(this);this.count = numCandy;if (numCandy > 0) {state = noMoneyState;}}public void insertCoins(){state.insertCoins();}public void coinsHopper(){state.coinsHopper();}public void pressSold(){state.pressSold();state.soldCandy();}void releaseCandy(){if(count!=0){System.out.println("你获得一个糖果");count=count-1;}}public State getNoMoneyState() {return noMoneyState;}public State getHasMoneyState() {return hasMoneyState;}public State getSoldState() {return soldState;}public State getSoldOutState() {return soldOutState;}public State getWinnerState() {return winnerState;}public State getState() {return state;}public int getCount() {return count;}public void setState(State state) {this.state = state;}@Overridepublic String toString() {return "GumballMachine [state=" + state + ", count=" + count + "]";}}

测试

package com.undergrowth.state.test;import static org.junit.Assert.*;import org.junit.Test;import com.undergrowth.state.GumballMachine;public class GumballMachineTest {@Testpublic void test() {GumballMachine gumball=new GumballMachine(10);System.out.println(gumball);gumball.insertCoins();gumball.pressSold();System.out.println(gumball);gumball.insertCoins();gumball.pressSold();System.out.println(gumball);gumball.coinsHopper();gumball.insertCoins();System.out.println(gumball);gumball.coinsHopper();System.out.println(gumball);gumball.insertCoins();gumball.pressSold();System.out.println(gumball);gumball.insertCoins();gumball.pressSold();gumball.insertCoins();gumball.pressSold();gumball.insertCoins();gumball.pressSold();System.out.println(gumball);}}

输出结果

GumballMachine [state=com.undergrowth.state.NoMoneyState@328c40, count=10]你投了5块钱你按下售出糖果按钮，即将售出糖果你获得一个糖果GumballMachine [state=com.undergrowth.state.NoMoneyState@328c40, count=9]你投了5块钱你按下售出糖果按钮，即将售出糖果你进入了赢家模式，会获得两个糖果你获得一个糖果你获得一个糖果GumballMachine [state=com.undergrowth.state.NoMoneyState@328c40, count=7]你没有投钱，甭想退钱你投了5块钱GumballMachine [state=com.undergrowth.state.HasMoneyState@95ef17, count=7]退币成功GumballMachine [state=com.undergrowth.state.NoMoneyState@328c40, count=7]你投了5块钱你按下售出糖果按钮，即将售出糖果你获得一个糖果GumballMachine [state=com.undergrowth.state.NoMoneyState@328c40, count=6]你投了5块钱你按下售出糖果按钮，即将售出糖果你获得一个糖果你投了5块钱你按下售出糖果按钮，即将售出糖果你获得一个糖果你投了5块钱你按下售出糖果按钮，即将售出糖果你获得一个糖果GumballMachine [state=com.undergrowth.state.NoMoneyState@328c40, count=3]

   状态模式：封装基于状态的行为，并将行为委托给当前状态