组合模式——java实现

问题描述：

用透明组合模式实现教材中的“文件夹浏览”这个例子。

类图：

java代码：

//AbstractFile.java
package shiyan10;

public abstract class AbstractFile 
{
    public abstract void add(AbstractFile element);
    public abstract void remove(AbstractFile element);
    public abstract void display();
}
//ImageFile.java
package shiyan10;

public class ImageFile extends AbstractFile
{
    private String fileName;
    public ImageFile(String filename)
    {
        this.fileName=new String();
        this.fileName=filename;
    }
    public void add(AbstractFile element)
    {
        System.out.println("add ImageFile");
    }
    public void remove(AbstractFile element)
    {
        System.out.println("remove ImageFile");
    }
    public void display()
    {
        System.out.print(fileName);
        System.out.println(" ImageFile");
    }
}
//TextFile.java
package shiyan10;

public class TextFile extends AbstractFile
{
    private String fileName;
    public TextFile(String filename)
    {
        this.fileName=new String();
        this.fileName=filename;
    }
    public void add(AbstractFile element)
    {
        System.out.println("add TextFile");
    }
    public void remove(AbstractFile element)
    {
        System.out.println("remove TextFile");
    }
    public void display()
    {
        System.out.print(fileName);
        System.out.println(" TextFile");
    }
}
//VideoFile.java
package shiyan10;

public class VideoFile extends AbstractFile
{
    private String fileName;
    public VideoFile(String filename)
    {
        this.fileName=new String();
        this.fileName=filename;
    }
    public void add(AbstractFile element)
    {
        System.out.println("add VideoFile");
    }
    public void remove(AbstractFile element)
    {
        System.out.println("remove VideoFile");
    }
    public void display()
    {
        System.out.print(fileName);
        System.out.println(" VideoFile");
    }
}
//Folder.java
package shiyan10;
import java.util.*;

public class Folder extends AbstractFile
{
    private String fileName;
    private ArrayList<AbstractFile> fileList=new ArrayList();
    public Folder(String filename)
    {
        this.fileName=new String();
        this.fileName=filename;
    }
    public void add(AbstractFile element)
    {
        fileList.add(element);
        System.out.println("add Folder");
    }
    public void remove(AbstractFile element)
    {
        fileList.remove(element);
        System.out.println("remove Folder");
    }
    public void display()
    {
        System.out.println(fileName);
        for(Object object:fileList)
        {
            ((AbstractFile)object).display();
        }
        System.out.println("****Folder display****");
    }
}
//Client.java
package shiyan10;
public class Client 
{
    public static void main(String a[])
    {
        AbstractFile obj1,obj2,obj3,obj4;
        Folder plate1,plate2,plate3;
        obj1=new ImageFile("a.jpg");
        obj2=new TextFile("b.txt");
        plate1=new Folder("Image_Text");
        plate1.add(obj1);
        plate1.add(obj2);
        
        obj3=new VideoFile("c.mp4");
        plate2=new Folder("Image_Video");
        plate2.add(obj1);
        plate2.add(obj3);
        
        obj4=new ImageFile("d.jpg");
        plate3=new Folder("Image_Text_Video_Folder");
        plate3.add(plate1);
        plate3.add(plate2);
        plate3.add(obj4);
        
        plate3.display();
        
    }
}

运行结果：