组合模式（Composite Pattern）属于结构型模式。组合模式又叫作部分整体模式，它是一种将对象组合成树状层次结构的模式，用来表示整体-部分的关系，使用户对单个对象和组合对象具有一致的访问性。组合模式有透明方式和安全方式两种实现方式
业务代码
//抽象节点
public abstract class Component {
abstract void add(Component component);
abstract void remove(Component component);
abstract Component getChild(int i);
abstract void operation();
}
//叶子节点
class Leaf extends Component{
private String name;
public Leaf(String name) {
this.name = name;
}
@Override
void add(Component component) {}
@Override
void remove(Component component) {}
@Override
Component getChild(int i) {
return null;
}
@Override
void operation() {
System.out.print(name);
}
}
//树枝节点
class Composite extends Component{
private ArrayList<Component> children = new ArrayList<>();
@Override
void add(Component component) {
children.add(component);
}
@Override
void remove(Component component) {
children.remove(component);
}
@Override
Component getChild(int i) {
return children.get(i);
}
@Override
void operation() {
children.forEach(Component::operation);
}
}客户端
public class Client {
public static void main(String[] args) {
Component level1 = new Composite();
level1.add(new Leaf("1"));
level1.add(new Leaf("2"));
Component level2 = new Composite();
level2.add(new Leaf("2.1"));
level1.add(level2);
level1.operation();
}
}
