composite模式及其在jsf中的应用

shape.java:
public interface shape {
public void draw();
}
compositeshape.java:
[code]public class compositeshape implements shape {
private vector comshape = new vector();
public void add(shape shape) {
comshape.add(shape);
}
public void draw() {
for( int i = 0; i < comshape.size(); i ++ ) {
shape shape = (shape) comshape.elementat(i);
shape.draw();
}
}
}

package com.interf;
public abstract class equipment {
private string name;
private double netprice;
private double discountprice;
public equipment(string name) {
this.name = name;
}
public abstract double netprice();
public abstract double discountprice();
}

package implequip;
import com.interf.equipment;
public class disk extends equipment {
public disk(string name) {
super(name);
// todo auto-generated constructor stub
}
//定义disk实价为1
public double netprice() {
return 1.;
}
//定义了disk折扣价格是0.5 对折。
public double discountprice() {
return .5;
}
}

package implequip;
import java.util.arraylist;
import java.util.iterator;
import java.util.list;
import java.util.nosuchelementexception;
import com.interf.equipment;
public class compositeequipment extends equipment {
private int i=0;
// 定义一个vector 用来存放'儿子'
private list equipment = new arraylist();
public compositeequipment(string name) {
super(name);
// todo auto-generated constructor stub
}
public boolean add(equipment equipment) {
this.equipment.add(equipment);
return true;
}
public double netprice() {
double netprice=0.;
iterator iter=equipment.iterator();
while(iter.hasnext())
netprice+=((equipment)iter.next()).netprice();
return netprice;
}
public double discountprice() {
double discountprice=0.;
iterator iter=equipment.iterator();
while(iter.hasnext())
discountprice+=((equipment)iter.next()).discountprice();
return discountprice;
}
// 注意这里，这里就提供用于访问自己组合体内的部件方法。
// 上面disk 之所以没有，是因为disk是个单独(primitive)的元素.
public iterator iter() {
return equipment.iterator() ;
}
// 重载iterator方法
public boolean hasnext() { return i<equipment.size(); }
// 重载iterator方法
public object next(){
if(hasnext())
return equipment.get(i++);
else
throw new nosuchelementexception();
}
}

上面compositeequipment继承了equipment,同时为自己里面的对象们提供了外部访问的方法,重载了iterator,iterator是java的collection的一个接口，是iterator模式的实现.
我们再看看compositeequipment的两个具体类:盘盒chassis和箱子cabinet，箱子里面可以放很多东西，如底板，电源盒，硬盘盒等；盘盒里面可以放一些小设备，如硬盘软驱等。无疑这两个都是属于组合体性质的。

cabinet.java:
package implequip;
public class cabinet extends compositeequipment {
public cabinet(string name) {
super(name);
// todo auto-generated constructor stub
}
public double netprice() {
return 1.+super.netprice();
}
public double discountprice() {
return .5+super.discountprice();
}
}

package implequip;
public class chassis extends compositeequipment {
public chassis(string name) {
super(name);
// todo auto-generated constructor stub
}
public double netprice() {
return 1.+super.netprice();
}
public double discountprice() {
return .5+super.discountprice();
}
}

package test;
import implequip.cabinet;
import implequip.chassis;
import implequip.disk;
public class compositetest {
/**
* @param args
*/
public static void main(string[] args) {
// todo auto-generated method stub
cabinet cabinet=new cabinet("tower");
chassis chassis=new chassis("pc chassis");
// 将pc chassis装到tower中 (将盘盒装到箱子里)
cabinet.add(chassis);
// 将一个10gb的硬盘装到 pc chassis (将硬盘装到盘盒里)
chassis.add(new disk("10 gb"));
// 调用 netprice()方法;
system.out.println("netprice="+cabinet.netprice());
system.out.println("discountprice="+cabinet.discountprice());
}
}