大话设计模式-外观模式

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需求
实现股民炒股。
实现
级别1

public class Stock1  
{  
    public void sell()  
    {  
        System.out.println("股票1卖出");  
    }  
    public void buy()  
    {  
        System.out.println("股票1买入");  
    }  
}

public class Stock2  
{  
    public void sell()  
    {  
        System.out.println("股票2卖出");  
    }  
    public void buy()  
    {  
        System.out.println("股票2买入");  
    }  
}  

public class Stock3  
{  
    public void sell()  
    {  
        System.out.println("股票3卖出");  
    }  
    public void buy()  
    {  
        System.out.println("股票3买入");  
    }  
}  

public class Realty1  
{  
    public void sell()  
    {  
        System.out.println("房地产1卖出");  
    }  
    public void buy()  
    {  
        System.out.println("房地产1买入");  
    }  
} 

public class NationalDebt1  
{  
    public void sell()  
    {  
        System.out.println("国债1卖出");  
    }  
    public void buy()  
    {  
        System.out.println("国债1买入");  
    }  
} 

public class Main  
{  
    public static void main(String[] args)  
    {  
        Stock1 gu1 = new Stock1();  
        Stock2 gu2 = new Stock2();  
        Stock3 gu3 = new Stock3();  
        NationalDebt1 nd1 = new NationalDebt1();  
        Realty1 rt1 = new Realty1();  
        gu1.buy();  
        gu2.buy();  
        gu3.buy();  
        nd1.buy();  
        rt1.buy();  
        gu1.sell();  
        gu2.sell();  
        gu3.sell();  
        nd1.sell();  
        rt1.sell();  
    }  
}  

这样的代码，用户需要了解股票、国债、房产情况，需要参与这些项目的具体买和卖。耦合性很高。
级别2

public class Fund  
{  
    Stock1          gu1;  
    Stock2          gu2;  
    Stock3          gu3;  
    NationalDebt1   nd1;  
    Realty1         rt1;  
    public Fund()  
    {  
        gu1 = new Stock1();  
        gu2 = new Stock2();  
        gu3 = new Stock3();  
        nd1 = new NationalDebt1();  
        rt1 = new Realty1();  
    }  
    public void buyFund() 
    {  
        gu1.buy();  
        gu2.buy();  
        gu3.buy();  
        nd1.buy();  
        rt1.buy();  
    }  
    public void sellFund()  
    {  
        gu1.sell();  
        gu2.sell();  
        gu3.sell();  
        nd1.sell();  
        rt1.sell();  
    }  
}  

public class Main  
{  
    public static void main(String[] args)  
    {  
        Fund jijin = new Fund();  
        jijin.buyFund();  
        jijin.sellFund();  
    }  
}  

外观模式，为子系统中的一组接口提供一个一致的界面，此模式定义了一个高层接口，这个接口使得这一子系统更加容易使用。

//四个子系统的类  
public class SubSystemOne  
{  
    public void methodOne()  
    {  
        System.out.println("子系统方法1");  
    }  
}  
public class SubSystemTwo  
{  
    public void methodTwo()  
    {  
        System.out.println("子系统方法2");  
    }  
}  
public class SubSystemThree  
{  
    public void methodThree()  
    {  
        System.out.println("子系统方法3");  
    }  
}  
public class SubSystemFour  
{  
    public void methodFour()  
    {  
        System.out.println("子系统方法4");  
    }  
}  
//外观类  
public class Facade  
{  
    SubSystemOne    one;  
    SubSystemTwo    two;  
    SubSystemThree  three;  
    SubSystemFour   four;  
    public Facade()  
    {  
        one = new SubSystemOne();  
        two = new SubSystemTwo();  
        three = new SubSystemThree();  
        four = new SubSystemFour();  
    }  
    public void methodA()  
    {  
        System.out.println("方法组A");  
        one.methodOne();  
        two.methodTwo();  
        four.methodFour();  
    }  
    public void methodB()  
    {  
        System.out.println("方法组B");  
        two.methodTwo();  
        three.methodThree();  
    }  
}  
//客户端代码  
public class Main  
{  
    public static void main(String[] args)  
    {  
        Facade facade = new Facade();   
        facade.methodA();  
        facade.methodB();  
    }  
}