图解设计模式-Strategy模式-白红宇

图解设计模式-Strategy模式

阅读量：6634 次

发布时间：2019-06-25

本文共 3534 字，大约阅读时间需要 11 分钟。

Strategy（算法）模式可以整体的替换算法的实现部分。

重点说明：

使用委托这种弱关联关系可以很方便的整体替换算法。

角色:

Strategy策略：该角色负责决定实现策略所需要的接口api。

ConcreteStrategy具体策略：该角色负责实现Strategy角色接口api。即负责实现具体的策略。

Context上下文：负责使用Strategy角色，Context角色保存了ConcreteStrategy角色的实例，并使用ConcreteStrategy角色去实现需求。

代码：

public class Hand {    public static final int GUU = 0;    public static final int CHO = 1;    public static final int PAA = 2;    public static final Hand[] hand = {            new Hand(GUU),            new Hand(CHO),            new Hand(PAA),    };    private int handValue;    private Hand(int handValue) {        this.handValue = handValue;    }    private static final String[] name = {      "石头","剪刀","布"    };    public static Hand getHand(int handValue) {        return hand[handValue];    }    public boolean isStrongerThan(Hand h){        return fight(h)== 1;    }    public boolean isWeakerThan(Hand h) {        return fight(h)== -1;    }    private int fight(Hand h) {        if(this==h){            return 0;        }else if((this.handValue+1)%3==h.handValue) {            return 1;        }else{         return -1;        }    }}

public interface Strategy {    public abstract Hand nextHand();    public abstract void study(boolean win);}

public class ProbStrategy implements Strategy {    private Random random;    private int preHandValue = 0;    private int currentHandValue =0;    private int[][] histroy = {            {
     1,1,1},            {
     1,1,1},            {
     1,1,1}    };    public ProbStrategy(int seed) {        this.random = new Random(seed);    }    private int getSum(int hv) {        int sum = 0;        for(int i=0;i<3;i++) {            sum +=histroy[hv][i];        }        return sum;    }    @Override    public Hand nextHand() {        int bet = random.nextInt(getSum(currentHandValue));        int handvalue = 0;        if(bet

public class WinningStrategy implements Strategy {    private Random random;    private  boolean won =false;    private Hand preHand;    public WinningStrategy(int seed) {        this.random = new Random(seed);    }    @Override    public Hand nextHand() {        if(!won) {            preHand = Hand.getHand(random.nextInt(3));        }        return preHand;    }    @Override    public void study(boolean win) {        won = win;    }}

public class Main {    public static void main(String[] args){        int seed0=1;        int seed1=2;        Play play1 = new Play("王五",new WinningStrategy(seed0));        Play play2 = new Play("王五",new ProbStrategy(seed1));        for(int i=0;i<1000;i++) {            Hand hand1 = play1.nextHand();            Hand hand2 = play2.nextHand();            if(hand1.isStrongerThan(hand2)) {                System.out.println("winner is "+play1);                play1.win();                play2.lose();            }else if(hand2.isStrongerThan(hand1)) {                System.out.println("winner is "+play2);                play2.win();                play1.lose();            }else {                System.out.println("even... ");                play2.even();                play1.even();            }        }    }}

执行结果：

winner is [王五:0 ganmes,0 win, 0 lose ]

even...

winner is [王五:3 ganmes,1 win, 0 lose ]

even...

winner is [王五:7 ganmes,2 win, 0 lose ]

winner is [王五:8 ganmes,3 win, 0 lose ]

winner is [王五:9 ganmes,0 win, 4 lose ]

winner is [王五:10 ganmes,4 win, 1 lose ]

winner is [王五:11 ganmes,1 win, 5 lose ]

winner is [王五:12 ganmes,5 win, 2 lose ]

winner is [王五:13 ganmes,2 win, 6 lose ]