composite-----设计模式

最新推荐文章于 2025-08-10 08:32:47 发布

原创最新推荐文章于 2025-08-10 08:32:47 发布 · 405 阅读

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文章标签：

#设计模式 #string #file #class #user

本文探讨了复合设计模式如何在文件系统中实现对文件夹与文件的一视同仁处理，通过Java代码实例展示了如何创建抽象类Entry，继承自它实现File和Directory类，并在add方法中实现了递归添加功能。

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1.对容器与内容一视同仁。

举例来说在文件系统中，既有文件夹又有文件，Composite设计模式将把文件夹与文件一视同仁，对其的处理没有差别。

2示例：

package com.cn;

import java.util.Iterator;
import java.util.Vector;

abstract class Entry {
	public abstract String getName();
	public abstract int getSize();
	public Entry add(Entry entry) throws FileTreatmentException {
		throw new FileTreatmentException();
	}
	public void printList() {
		printList("");
	}
	protected abstract void printList(String prefix);
	public String toString() {
		return getName() + "(" + getSize() + ")";
	}
}



class File extends Entry {
	String name;
	int size;
	public File(String name, int size) {
		this.name = name;
		this.size = size;
	}
	public String getName() {
		return name;
	}
	public int getSize() {
		return size;
	}
	protected void printList(String prefix) {
		System.out.println(prefix + "/" + this);
	}
}


class Directory extends Entry {
	private String name;
	private Vector<Entry> directory = new Vector<Entry>();
	public Directory(String name) {
		this.name = name;
	}
	public String getName() {
		return name;
	}
	public int getSize() {
		int size = 0;
		Iterator<Entry> it = directory.iterator();
		while(it.hasNext()) {
			Entry entry = (Entry)it.next();
			size += entry.getSize();
		}
		return size;
	}
	public Entry add(Entry entry) {
		directory.add(entry);
		return this;
	}
	protected void printList(String prefix) {
		System.out.println(prefix + "/" + this);
		Iterator<Entry> it = directory.iterator();
		while(it.hasNext()) {
			Entry entry = (Entry)it.next();
			entry.printList(prefix + "/" + name); 
		}
	}
}


class FileTreatmentException extends RuntimeException {
	private static final long serialVersionUID = 1L;
	public FileTreatmentException() {
		
	}
	public FileTreatmentException(String msg) {
		super(msg);
	}
	
}

public class Main {
	public static void main(String[] args) {
		try {
			System.out.println("Making root entries...");
			Directory rootdir = new Directory("root");
			Directory bindir = new Directory("bin");
			Directory tmpdir = new Directory("tmp");
			Directory usrdir = new Directory("usr");
			
			rootdir.add(bindir);
			rootdir.add(tmpdir);
			rootdir.add(usrdir);
			bindir.add(new File("vi",10000));
			bindir.add(new File("latex",20000));
			rootdir.printList();
			
			System.out.println("");
			System.out.println("Making user entries..");
			Directory yuki = new Directory("yuki");
			Directory hanakko = new Directory("{hanako");
			Directory tomura = new Directory("tomura");
			usrdir.add(yuki);
			usrdir.add(hanakko);
			usrdir.add(tomura);
			
			yuki.add(new File("diary.html",100));
			yuki.add(new File("Composite.java",300));
			hanakko.add(new File("memo.tex",400));
			tomura.add(new File("game.doc",400));
			rootdir.printList();
			Entry file = new File("dd",200).add(tomura);
			tomura.add(file);
			
			
		} catch (FileTreatmentException e) {
			e.printStackTrace();
		}
	}
}

File 与 Directory 都继承Entry类，他们都有

public abstract String getName();

public abstract int getSize();

public Entry add(Entry entry) ；

这几个方法。

在子类中在提供有差别的处理。