一，组合模式详解
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概念
将对象以树形结构组织起来，以达成“部分-整体”的层次结构，使得客户端对单个对象和组合对象的使用具有一致性
树的结构-->组合设计模式
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使用场景
(1)需要表示一个对象整体或部分层次
(2)让客户能忽略不同对象的层次变化
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UML
- 代码示例
public abstract class Component {
private String name;
public Component(String name) {
this.name = name;
}
public abstract void doSomeThing();
public abstract void addChild(Component component);
public abstract void removeChild(Component component);
public abstract Component getChild(int position);
}
public class Composite extends Component {
private List<Component> mFileList;
public Composite(String name) {
super(name);
mFileList = new ArrayList<>();
}
@Override
public void doSomeThing() {
if (null != mFileList) {
for (Component c : mFileList) {
c.doSomeThing();
}
}
}
@Override
public void addChild(Component component) {
mFileList.add(component);
}
@Override
public void removeChild(Component component) {
mFileList.remove(component);
}
@Override
public Component getChild(int index) {
return mFileList.get(index);
}
}
public class Leaf extends Component {
public Leaf(String name) {
super(name);
}
@Override
public void doSomeThing() {
}
@Override
public void addChild(Component component) {
throw new UnsupportedOperationException();
}
@Override
public void removeChild(Component component) {
throw new UnsupportedOperationException();
}
@Override
public Component getChild(int position) {
throw new UnsupportedOperationException();
}
}
Composite root = new Composite("root");
Composite branch1 = new Composite("branch1");
Composite branch2 = new Composite("branch2");
Composite branch3 = new Composite("branch3");
Leaf leaf1 = new Leaf("leaf1");
Leaf leaf2 = new Leaf("leaf2");
Leaf leaf3 = new Leaf("leaf3");
branch1.addChild(leaf1);
branch3.addChild(leaf2);
branch3.addChild(leaf3);
root.addChild(branch1);
root.addChild(branch2);
root.addChild(branch3);
root.doSomeThing();
