JAVA设计模式之【装饰者模式】

装饰模式

    对新房进行装修并没有改变房屋的本质，但它可以让房子变得更漂亮、更温馨、更实用。
    在软件设计中，对已有对象（新房）的功能进行扩展（装修）。
    把通用功能封装在装饰器中，用到的地方进行调用。
    装饰模式是一种用于替代继承的技术，使用对象之间的关联关系取代类之间的继承关系。引入装饰类，扩充新功能。
    角色
        抽象构件
        具体构件
        抽象装饰类
        具体装饰类

案例一，窗体装饰

1.组件类

package Decorator; // 装饰者模式

/**
 * Created by Jiqing on 2016/10/13.
 */
abstract class Component {
    public abstract void display();
}

2.组件装饰者

package Decorator;

/**
 * Created by Jiqing on 2016/10/13.
 */
public class ComponentDecorator extends Component{
    private Component component; // 维持对抽象构件类型对象的引用
    public ComponentDecorator(Component component){
        this.component = component;
    }

    public void display() {
        component.display();
    }

}

3.继承类ListBox

package Decorator;

/**
 * Created by Jiqing on 2016/10/13.
 */
public class ListBox extends Component{
    public void display() {
        System.out.println("显示列表框！");
    }
}

4.继承类TextBox

package Decorator;

/**
 * Created by Jiqing on 2016/10/13.
 */
public class TextBox extends Component{
    public void display() {
        System.out.println("显示文本框！");
    }
}

5.继承类Window

package Decorator;

/**
 * Created by Jiqing on 2016/10/13.
 */
public class Window extends Component{
    public void display() {
        System.out.println("显示窗体！");
    }
}

6.黑框装饰者

package Decorator;

/**
 * Created by Jiqing on 2016/10/14.
 */
public class BlackBoarderDecorator extends ComponentDecorator{
    public BlackBoarderDecorator(Component component) {
        super(component);
    }

    public void display() {
        this.setBlackBoarder();
        super.display();
    }

    public void setBlackBoarder() {
        System.out.println("为构件增加黑色边框！");

    }
}

7.滚动条装饰者

package Decorator;

/**
 * Created by Jiqing on 2016/10/14.
 */
public class ScrollBarDecorator extends ComponentDecorator{
    public ScrollBarDecorator (Component component) {
        super(component); // 调用父类构造函数
    }

    public void display() {
        this.setScrollBar();
        super.display();
    }

    public void setScrollBar() {
        System.out.println("为构件增加滚动条！");
    }
}

8.客户端调用

package Decorator; // 装饰者模式

/**
 * Created by Jiqing on 2016/10/14.
 */
public class Client {
    public static void main(String args[]) {
        Component component,componentSB,componentBB;
        component = new Window();
        componentSB = new ScrollBarDecorator(component);
        componentSB.display();
        System.out.println("--------------------");
        componentBB = new BlackBoarderDecorator(componentSB);
        componentBB.display();
    }
}

执行结果

为构件增加滚动条！
显示窗体！
--------------------
为构件增加黑色边框！
为构件增加滚动条！
显示窗体！

　案例二，密文装饰

1.密文接口

package Decorator.sample2;

/**
 * Created by Jiqing on 2016/10/14.
 */
public interface Cipher // 密文接口
{
    public String encrypt(String plainText);
}

2.密文装饰者

package Decorator.sample2;

/**
 * Created by Jiqing on 2016/10/14.
 */
public class CipherDecorator implements Cipher{
    private Cipher cipher;
    public CipherDecorator(Cipher cipher) {
        this.cipher = cipher;
    }

    public String encrypt(String plainText) {
        return cipher.encrypt(plainText);
    }
}

3.密文接口实现类

package Decorator.sample2;

/**
 * Created by Jiqing on 2016/10/14.
 */
public final class SimpleCipher implements Cipher // 简单密文继承密文
{
    public String encrypt(String plainText)
    {
        String str="";
        for(int i=0;i<plainText.length();i++)
        {
            char c=plainText.charAt(i);
            if(c>='a'&&c<='z')
            {
                c+=6;
                if(c>'z') c-=26;
                if(c<'a') c+=26;
            }
            if(c>='A'&&c<='Z')
            {
                c+=6;
                if(c>'Z') c-=26;
                if(c<'A') c+=26;
            }
            str+=c;
        }
        return str;
    }
}

4.复杂加密装饰者

package Decorator.sample2;

/**
 * Created by Jiqing on 2016/10/14.
 */
public class ComplexCipher extends CipherDecorator // 复杂密文
{
    public ComplexCipher(Cipher cipher)
    {
        super(cipher);
    }

    public String encrypt(String plainText)
    {
        String result=super.encrypt(plainText);
        result= this.reverse(result);
        return result;
    }

    public String reverse(String text)
    {
        String str="";
        for(int i=text.length();i>0;i--)
        {
            str+=text.substring(i-1,i);
        }
        return str;
    }
}

5.先进加密装饰者

package Decorator.sample2;

/**
 * Created by Jiqing on 2016/10/14.
 */
public class AdvancedCipher extends CipherDecorator{
    public AdvancedCipher(Cipher cipher) {
        super(cipher);
    }

    public String encrypt(String plainText) { // 加密处理
        String result=super.encrypt(plainText);
        result=mod(result);
        return result;
    }

    public String mod(String text)
    {
        String str="";
        for(int i=0;i<text.length();i++)
        {
            String c=String.valueOf(text.charAt(i)%6);
            str+=c;
        }
        return str;
    }
}

6.客户端

package Decorator.sample2;

/**
 * Created by Jiqing on 2016/10/14.
 */
public class Client {
    public static void main(String args[])
    {
        String password="Jiqing9006";  //明文
        String cpassword;       //密文
        Cipher sc,ac,cc;

        sc=new SimpleCipher();
        cpassword=sc.encrypt(password);
        System.out.println(cpassword);
        System.out.println("---------------------");

        cc=new ComplexCipher(sc);
        cpassword=cc.encrypt(password);
        System.out.println(cpassword);
        System.out.println("---------------------");

        ac=new AdvancedCipher(cc);
        cpassword=ac.encrypt(password);
        System.out.println(cpassword);
        System.out.println("---------------------");
    }
}

执行结果

Powotm9006
---------------------
6009mtowoP
---------------------
0003123532
---------------------