Composite_Pattern-优快云博客

本文链接：https://blog.youkuaiyun.com/GZHarryAnonymous/article/details/82834285

本文深入探讨了软件设计中的组合模式，通过实例代码展示了如何构建树形结构来表示部分整体层次结构，使得客户能够一致地使用单个对象和组合对象。文章解释了透明模式和安全模式的区别，并提供了实际应用案例。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

package composite_pattern;

public abstract class Component {
protected String name;

public Component(String name) {
this.name = name;
}

public abstract void add(Component c);

public abstract void remove(Component c);

public abstract void display(int depth);

public abstract void setStructure(char tag, int depth);
}

package composite_pattern;

import java.util.ArrayList;

public class Composite extends Component {
private ArrayList<Component> children = new ArrayList<Component>();

public Composite(String name) {
super(name);
}

@Override
public void add(Component c) {
children.add(c);
}

@Override
public void remove(Component c) {
children.remove(c);
}

@Override
public void setStructure(char tag, int depth) {
for (int i = 0; i < depth; i++) {
System.out.print(tag);
}
}

@Override
public void display(int depth) {
setStructure('-', depth);
System.out.println(name);
for (Component c : children) {
c.display(depth + 2);
}
}
}

package composite_pattern;

public class Leaf extends Component {
public Leaf(String name) {
super(name);
}

@Override
public void add(Component c) {
System.out.println("Can not add to a leaf.");
}

@Override
public void remove(Component c) {
System.out.println("Can not remove from a leaf.");
}

@Override
public void setStructure(char tag, int depth) {
for (int i = 0; i < depth; i++) {
System.out.print(tag);
}
}

@Override
public void display(int depth) {
setStructure('-', depth);
System.out.println(name);
}
}

package composite_pattern;

public class Main {
public static void main(String args[]) {
Composite root = new Composite("root");
root.add(new Leaf("Leaf A"));
root.add(new Leaf("Leaf B"));

Composite comp = new Composite("Composite X");
comp.add(new Leaf("Leaf XA"));
comp.add(new Leaf("Leaf XB"));

root.add(comp);

Composite comp2 = new Composite("Composite XY");
comp2.add(new Leaf("Leaf XYA"));
comp2.add(new Leaf("Leaf XYB"));

comp.add(comp2);

root.add(new Leaf("Leaf C"));

Leaf leaf = new Leaf("Leaf D");
root.add(leaf);
root.remove(leaf);
root.display(1);
}
}
/*
* The composite_pattern is just like the structure of "Tree". The Component is
* the abstraction of Leaf and Composite. The Composite can own its children but
* the Leaf not.This is the "transparent mode".
* But there is a question:why do we implement the methods of "add" and "remove" if
* we actually don't need it in "Leaf" ?It's ridiculous!But on the other hand,it does
* make the client more convenient so that they can omit the step of distinguishing
* whether the current node is the leaf or not.
* when we remove the method of "add" and "remove" in the Component,it is called
* the "safe mode".How to choose them?It depends on the specific situation.
*
*/