[UML] 物件導向分析與設計

介紹

今天花了點時間看了物件導向分析與設計，看了前四章的感覺是，這本書花了很多時間在指導我們如何分析客戶的需求，如何寫出良好的 user cases ，當然對於程式的封裝也有稍微提及。
不過今天要介紹的是UML圖




UML

         

             是系統分析以及設計的重要產物，也是實作以及測試的依據。

下面這張圖是 head first 物件導向分析與設計裡面的一個 sample，
使用者希望能有一個 Remote 能夠在按下按鈕的時候， DogDoor 會打開/關閉，
然後也希望家裡的狗 Bark 的時候， DogDoor 可以 Recognize 是自己家的狗然後開門。

上圖中  Remote -> DogDoor 之間的數字  1 代表著  

Remote has 1 個 DogDoor

相同的  BarkRecognizer also has 1個 DogDoor

DogDoor has n 個 Bark  而DogDoor 可以在 allowedBarks的屬性裡儲存任意數量的Bark

看完了UML圖以及解釋之後接下來就是實作部分

Sample Code

Bark.java

  
public class Bark {

 /**
  * @param args
  */
 private String sound;
 public Bark(String sound)
 {
  this.sound = sound;
 }
 public String getSound()
 {
  return sound;
 }
 public boolean equals(Bark bark)
 {
  if(bark.getSound().equals(this.sound))
   return true;
  return false;
 }
} 

BarkRecognizer.java

public class BarkRecognizer {

 /**
  * @param args
  */
 private DogDoor door;
 public BarkRecognizer(DogDoor door)
 {
  this.door = door;
 }
 public void recognize(Bark bark)
 {
  java.util.List<Bark> allowedBarks = door.getAllowedBarks();
  for (Bark allowedBark : allowedBarks) {
   if(bark.equals(allowedBark))
   {
    door.Open();
    return;
   }
  }
  System.out.println("Door is not Open");
 }
}

DogDoor.java

public class DogDoor {

 /**
  * @param args
  */
 private List<Bark> allowedBarks = new ArrayList<Bark>();   
 private boolean Open=false;
 public void Open()
 {
  System.out.println("Door Open");
  final Timer timer = new Timer();
  timer.schedule(new TimerTask(){

   @Override
   public void run() {
    // TODO Auto-generated method stub
    Close();
    timer.cancel();
   }
   
  },5000);
 }
 public void Close()
 {
  System.out.println("Door Close");
 }
 public boolean IsOpen()
 {
  return Open; 
 }
 public void addAllowedBark(Bark bark)
 {
  allowedBarks.add(bark);
 }
 public List<Bark> getAllowedBarks()
 {
  return allowedBarks;
 }
}

Remote.java

public class Remote {

 /**
  * @param args
  */
 private DogDoor door;
 public Remote(DogDoor door)
 {
  this.door = door;
 }
 public void pressButton()
 {
  if(door.IsOpen())
   door.Close();
  door.Open();
 }
}

接著拿出head first 裡面所提供的測試檔案


Test

 public static void main(String[] args) {
  // TODO Auto-generated method stub
  DogDoor door = new DogDoor();
  door.addAllowedBark(new Bark("rowlf"));
  door.addAllowedBark(new Bark("rooowlf"));
  door.addAllowedBark(new Bark("rawlf"));
  door.addAllowedBark(new Bark("woof"));
  BarkRecognizer recognizer = new BarkRecognizer(door);
  Remote remote = new Remote(door);
  
  System.out.println("Bruce starts barking.");
  recognizer.recognize(new Bark("rowlf"));
  
  System.out.println("Bruce has gone outside...");
  
  try{
   Thread.currentThread().sleep(6000);
  }catch(InterruptedException ex)
  {
   
  }
  
  System.out.println("Bruce's all done...");
  System.out.println("but he's stuck outside...");
  
  Bark smallDogBark = new Bark("open the door");
  System.out.println("A small dog starts barking.");
  recognizer.recognize(smallDogBark);
  
  System.out.println("Bruce starts barking");
  recognizer.recognize(new Bark("rowlf"));
  System.out.println("Bruce's Back inside");
  
 }

Result

Bruce starts barking.
Door Open
Bruce has gone outside...
Door Close
Bruce's all done...
but he's stuck outside...
A small dog starts barking.
Door is not Open
Bruce starts barking
Door Open
Bruce's Back inside

Door Close



結論

這次展示了如何從UML 到程式的coding
UML就有點像是蓋房子之前的藍圖，
有了藍圖就可以降低user想蓋巴黎鐵塔結果developer卻蓋出金字塔的問題。
我想這對user 來說應該也算是一大福音吧 XD