设计模式之装饰模式

定义:动态地给一个对象添加一些额外的职责，就增加功能来说,装饰模式比生成子类更为灵活。层层包装，增强功能。

在装饰模式中的各个角色有：

　　（1）抽象构件（Component）角色：给出一个抽象接口，以规范准备接收附加责任的对象。
　　（2）具体构件（Concrete Component）角色：定义一个将要接收附加责任的类。
　　（3）装饰（Decorator）角色：持有一个构件（Component）对象的实例，并实现一个与抽象构件接口一致的接口。
　　（4）具体装饰（Concrete Decorator）角色：负责给构件对象添加上附加的责任。

“`
public abstract class Girl {
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String description = “no particular”;
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public String getDescription(){
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return description;
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}
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}
AmericanGirl.java

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public class AmericanGirl extends Girl {
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public AmericanGirl() {
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description = “+American”;
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}
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}
EuropeanGirl.java

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public class EuropeanGirl extends Girl {
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public EuropeanGirl(){
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description = “+European”;
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}
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}
GirlDecorator.java

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public abstract class GirlDecorator extends Girl {
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public abstract String getDescription();
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}
Science.java

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public class Science extends GirlDecorator {
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private Girl girl;
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public Science(Girl girl){
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this.girl = girl;
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}
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@Override
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public String getDescription() {
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return this.girl.getDescription() + “+Like Science”;
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}
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public void caltulateStuff() {
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System.out.println(“scientific calculation!”);
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}
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}
Art.java

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public class Art extends GirlDecorator {
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private Girl girl;
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public Art(Girl girl){
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this.girl = girl;
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}
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@Override
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public String getDescription() {
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return this.girl.getDescription() + “+Like Art”;
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}
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public void draw() {
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System.out.println(“draw pictures!”);
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}
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}
Main.java

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public class Main {
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public static void main(String[] args) {
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//普通美国女孩
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Girl g1 = new AmericanGirl();
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System.out.println(g1.getDescription());
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//喜欢科学的
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Science g2 = new Science(g1);
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System.out.println(g2.getDescription());
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//喜欢艺术的
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Art g3 = new Art(g2);
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System.out.println(g3.getDescription());
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}
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}

/scienceGirl->artGirl->girl-> new ChinaGirl(); /

“public class DecoratorPattern {

public static void main(String[] args) {
    // TODO 自动生成的方法存根
    Girl girl = new ChinaGirl();
    System.out.println(girl.getDescription()); //China girl的getDescription


    GirlDecoator artGirl = new Art(girl);
    System.out.println(artGirl.getDescription());


    GirlDecoator scienceGirl = new Science(artGirl);
    System.out.println(scienceGirl.getDescription());

    /*scienceGirl->artGirl->girl-> new ChinaGirl(); */

}

}