Java设计模式 - 装饰模式
装饰模式在不链接其结构的情况下向现有对象添加新功能。
它是一种结构型模式，因为它充当现有类的包装器。
装饰模式创建一个装饰器类来包装原始类并提供其他功能。
例子
interface Printer {
void print();
}
class PaperPrinter implements Printer {
@Override
public void print() {
System.out.println("Paper Printer");
}
}
class PlasticPrinter implements Printer {
@Override
public void print() {
System.out.println("Plastic Printer");
}
}
abstract class PrinterDecorator implements Printer {
protected Printer decoratedPrinter;
public PrinterDecorator(Printer d){
this.decoratedPrinter = d;
}
public void print(){
decoratedPrinter.print();
}
}
class Printer3D extends PrinterDecorator {
public Printer3D(Printer decoratedShape) {
super(decoratedShape);
}
@Override
public void print() {
System.out.println("3D.");
decoratedPrinter.print();
}
}
public class Main {
public static void main(String[] args) {
Printer plasticPrinter = new PlasticPrinter();
Printer plastic3DPrinter = new Printer3D(new PlasticPrinter());
Printer paper3DPrinter = new Printer3D(new PaperPrinter());
plasticPrinter.print();
plastic3DPrinter.print();
paper3DPrinter.print();
}
}
上面的代码生成以下结果。
Plastic Printer
3D.
Plastic Printer
3D.
Paper Printer