軟體設計樣式#Composite

Composite Pattern

複合模式-我們在真實世界可以將東西的數量簡單分為複數和單數，在程式同樣道理，我們設計時可以將元件(Component)或是物件(Object)是分為複數和單數。設計模式是將單數個體和負數的個體可以同時用一個介面(Interface)做規格，來完成加入元件、取得元件和刪除元件的動作。

架構圖:











例子:
 我們做檔案的上傳程式，它可以做單筆或是多筆上傳，

FileCommonComponent.java

//Componentpublic abstract class FileCommonComponent {

 // define attribute private String fileName ;
 private long   fileSize ;

 //constractor public FileCommonComponent()
 { }

 public FileCommonComponent(String filename, long filesize)
 {
  this.fileName = filename ;
  this.fileSize = filesize ;
 }

 // abstract method public abstract void  getFileComponentSize() ;

}

Filecomponent .java

//component
public class Filecomponent extends FileCommonComponent{

 private String fileName ;
 private long fileSize ;

 public Filecomponent(String filename , long filesize) {
  // TODO Auto-generated constructor stub
  super(filename, filesize) ;
  this.fileName = filename ;
  this.fileSize = filesize ;

 }

 ///method
    public void getFileComponentSize()
    {
     StringBuffer strbuffer = new StringBuffer() ;
     strbuffer.append("檔案名稱"+this.fileName+",檔案大小:"+this.fileSize);
     System.out.println(strbuffer.toString())  ;
    }
}

FileComposites.java 

public class FileComposites extends FileCommonComponent{

 Vector fileVect = new Vector() ;
 Filecomponent component ;

    public FileComposites()
    {
     super() ;
    }

    //method    public void addFileComponent(FileCommonComponent component)
    {
     fileVect.add(component) ;
   
    }

    public Filecomponent getFileComponentSize(int location)
    {
     Filecomponent component = (Filecomponent)fileVect.elementAt(location) ;
     return component ;
    }
   
    public void getFileComponentSize()
    {
     Enumeration<FileCommonComponent> e = this.fileVect.elements() ;
   
     while(e.hasMoreElements())
     {
      FileCommonComponent f = e.nextElement() ;
      f.getFileComponentSize();
     }

    } 
}

TestComposite.java

 public class TestComposite {

 public static void main(String[] args)
 {
   FileCommonComponent component = new Filecomponent("test.txt",(long) 1000.5f);
   FileCommonComponent component2 = new Filecomponent("test2.txt",(long) 1000.5f);
 
   FileComposites composites = new FileComposites() ;

   composites.addFileComponent(component);
  composites.addFileComponent(component2);
  composites.getFileComponentSize() ;

  }
}