代碼：
public class Invoice {
public void printInvoice(){
System.out.println("This is the content of the invoice!");
}
}
class Decorator extends Invoice{
protected Invoice ticket;
public Decorator(Invoice t){
ticket = t;
}
public void printInvoice() {
if (ticket!=null){
ticket.printInvoice();
}
}
}
class HeadDecorator extends Decorator {
public HeadDecorator(Invoice t){
super(t);
}
public void printInvoice(){
System.out.println("This is the header of invoice!");
super.printInvoice();
}
}
class FootDecorator extends Decorator {
public FootDecorator(Invoice t){
super(t);
}
public void printInvoice(){
super.printInvoice();
System.out.println("This is the footnote of the invoice!");
}
}
class test {
public static void main(String[] args){
Invoice t = new Invoice();
Invoice ticket;
ticket = new HeadDecorator(new FootDecorator(t));
ticket.printInvoice();
System.out.println("-------------");
ticket = new HeadDecorator(new FootDecorator(null));
ticket.printInvoice();
}
}
輸出：
This is the header of invoice!
This is the content of the invoice!
This is the footnote of the invoice!
-------------
This is the header of invoice!
This is the footnote of the invoice!
想問下super的呼叫方法是怎么呼叫的，只呼叫一次嗎？
uj5u.com熱心網友回復：
看著挺惡心的。。 debug走一遍就明白了。。第一次輸出的時候，實際型別是header，ticket屬性型別是foot，第二次實際型別是foot，ticket屬性型別是Invoice。。所以順序是 header-->content-->invoice
"-------------"后邊沒細看，思路是一樣的。
uj5u.com熱心網友回復：
兩種方式，1. super調2. 父類定義一個抽象方法，子類去實作
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標籤：Java EE
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