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。
1 package com.xingoo.composite.safe;
2
3 import java.util.ArrayList;
4 import java.util.List;
5
6 interface Component{
7 Composite getCmposite();
8 void sampleComposite();
9 }
10
11 class Leaf implements Component{
12
13 public Composite getCmposite() {
14 return null;
15 }
16
17 public void sampleComposite() {
18 System.out.println("Leaf operation");
19 }
20
21 }
22
23 class Composite implements Component{
24
25 private List<Component> list = new ArrayList();
26
27 public void add(Component component){
28 list.add(component);
29 }
30
31 public void remove(Component component){
32 list.remove(component);
33 }
34
35 public Composite getCmposite() {
36 return this;
37 }
38
39 public void sampleComposite() {
40 System.out.println("Composite operation");
41 for(Component com : list){
42 com.sampleComposite();
43 }
44 }
45
46 }
47 public class Client {
48 public static void main(String[] args) {
49 Component leaf1 = new Leaf();
50 Component leaf2 = new Leaf();
51 Component composite = new Composite();
52 composite.getCmposite().add(leaf1);
53 composite.getCmposite().add(leaf2);
54 composite.getCmposite().sampleComposite();
55 }
56 }执行结果
代码语言：javascript复制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。
1 package com.xingoo.composite.transparent;
2
3 import java.util.ArrayList;
4 import java.util.List;
5
6 interface Component{
7 public void SampleOperation();
8 public void add(Component component);
9 public void remove(Component component);
10 public Component getComponent();
11 }
12
13 class Leaf implements Component{
14 public void SampleOperation() {
15 System.out.println("leaf operation!");
16 }
17
18 public void add(Component component) {
19
20 }
21
22 public void remove(Component component) {
23
24 }
25
26 public Component getComponent(){
27 return this;
28 }
29 }
30
31 class Composite implements Component{
32
33 private List<Component> list = new ArrayList();
34
35 public void SampleOperation() {
36 System.out.println("composite operation!");
37 for(Component com : list){
38 com.getComponent().SampleOperation();
39 }
40 }
41
42 public void add(Component component) {
43 list.add(component);
44 }
45
46 public void remove(Component component) {
47 list.remove(component);
48 }
49
50 public Component getComponent(){
51 return this;
52 }
53 }
54 public class Client {
55 public static void main(String[] args) {
56 Component leaf1 = new Leaf();
57 Component leaf2 = new Leaf();
58 Component leaf3 = new Leaf();
59 Component composite1 = new Composite();
60 Component composite = new Composite();
61
62 composite1.add(leaf3);
63
64 composite.getComponent().add(leaf1);
65 composite.getComponent().add(leaf2);
66 composite.getComponent().add(composite1);
67
68 composite.getComponent().SampleOperation();
69 }
70 }本例中的结构层次
执行结果
代码语言：javascript复制composite operation!
leaf operation!
leaf operation!
composite operation!
leaf operation!
