前言：【模式总览】——————————by xingoo
模式意图
使对象组合成树形的结构。使用户对单个对象和组合对象的使用具有一致性。
应用场景
1 表示对象的 部分-整体 层次结构
2 忽略组合对象与单个对象的不同，统一的使用组合结构中的所有对象。
模式结构
【安全的组合模式】
这种组合模式，叶子节点，也就是单个对象不具有对象的控制功能。仅仅有简单的业务操作。
package com.xingoo.composite.safe; import java.util.ArrayList;
import java.util.List; interface Component{
Composite getCmposite();
void sampleComposite();
} class Leaf implements Component{ public Composite getCmposite() {
return null;
} public void sampleComposite() {
System.out.println("Leaf operation");
} } class Composite implements Component{ private List<Component> list = new ArrayList(); public void add(Component component){
list.add(component);
} public void remove(Component component){
list.remove(component);
} public Composite getCmposite() {
return this;
} public void sampleComposite() {
System.out.println("Composite operation");
for(Component com : list){
com.sampleComposite();
}
} }
public class Client {
public static void main(String[] args) {
Component leaf1 = new Leaf();
Component leaf2 = new Leaf();
Component composite = new Composite();
composite.getCmposite().add(leaf1);
composite.getCmposite().add(leaf2);
composite.getCmposite().sampleComposite();
}
}
执行结果
Composite operation
Leaf operation
Leaf operation
【透明的组合模式】
这种组合模式，叶子节点与组合对象具有相同的方法，外表看来毫无差异。不过叶子节点的处理方法默认为空。忽略叶子节点，与组合对象的差异性。
package com.xingoo.composite.transparent; import java.util.ArrayList;
import java.util.List; interface Component{
public void SampleOperation();
public void add(Component component);
public void remove(Component component);
public Component getComponent();
} class Leaf implements Component{
public void SampleOperation() {
System.out.println("leaf operation!");
} public void add(Component component) { } public void remove(Component component) { } public Component getComponent(){
return this;
}
} class Composite implements Component{ private List<Component> list = new ArrayList(); public void SampleOperation() {
System.out.println("composite operation!");
for(Component com : list){
com.getComponent().SampleOperation();
}
} public void add(Component component) {
list.add(component);
} public void remove(Component component) {
list.remove(component);
} public Component getComponent(){
return this;
}
}
public class Client {
public static void main(String[] args) {
Component leaf1 = new Leaf();
Component leaf2 = new Leaf();
Component leaf3 = new Leaf();
Component composite1 = new Composite();
Component composite = new Composite(); composite1.add(leaf3); composite.getComponent().add(leaf1);
composite.getComponent().add(leaf2);
composite.getComponent().add(composite1); composite.getComponent().SampleOperation();
}
}
本例中的结构层次
执行结果
composite operation!
leaf operation!
leaf operation!
composite operation!
leaf operation!