JavaMe開發：也說MVC設計模式(1)

【更新】本文將適時做出更新，所以現在不是終稿，如有不當之處，敬請指出。

【問題描述】介紹設計模式的文章和書很多，但只有使用時，才能理解設計模式的妙處。接上一篇《JavaMe連載(2)-低級界面繪圖之菜單》，本文一則對UIController作出解釋，一則將自己理解的MVC設計模式，結合實例，與大家交流學習。

【理論】什麼是MVC？

MVC就是模型(model)、視圖(vIEw)和控制(control)。什麼是模型呢？本例中，模型就是對數據使用時的封裝。視圖很容易理解，那就是顯示內容的具體表示。控制呢？有很多人對視圖和控制分不清。在本例中，控制包含視圖控制器以及方法的封裝。

【實例】

1、先看工程結構，如圖1所示。

圖1 工程結構

工程中將用戶數據單獨封裝，作為model。供控制器和視圖調用。將顯示頁面單獨封裝，作為視圖。將視圖控制器UIController和常用方法封裝為util。UIController就是控制。

2、UML圖(後續更新時補充)

先看代碼，再分析工作機理

【代碼清單】

MainMidlet.Java

package com.token.midlet;  
 
import Java.io.IOException;  
 
import Javax.microedition.lcdui.*;  
import Javax.microedition.midlet.MIDlet;  
import Javax.microedition.midlet.MIDletStateChangeException;  
import com.token.util.UIController;  
 
public class MainMidlet extends MIDlet {  
      
    private Display display;  
    private static UIController controller;  
    public MainMidlet() {  
        // TODO Auto-generated constructor stub  
        super();  
        display=Display.getDisplay(this);  
          
    }  
 
    /* (non-Javadoc)  
     * @see Javax.microedition.midlet.MIDlet#pauseApp()  
     */ 
    protected void startApp() throws MIDletStateChangeException {  
        controller=new UIController(this);  
        try {  
            controller.init();  
        } catch (IOException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
        }//初始化RecordStore  
    }  
 
    /* (non-Javadoc)  
     * @see Javax.microedition.midlet.MIDlet#pauseApp()  
     */ 
    protected void pauseApp() {  
        this.notifyPaused();  
    }  
 
    /* (non-Javadoc)  
     * @see Javax.microedition.midlet.MIDlet#destroyApp(boolean)  
     */ 
    protected void destroyApp(boolean arg0) throws MIDletStateChangeException {  
        controller=null;  
          
    }  
      
    public void setCurrent(Displayable disp){  
        display.setCurrent(disp);  
    }  
      
    public void setCurrent(Alert alert, Displayable disp){  
        display.setCurrent(alert, disp);  
    }  
    public Displayable getCurrent(){  
        return display.getCurrent();  
    }  
      
    public void exit(boolean arg0){  
        try{  
            destroyApp(arg0);  
            notifyDestroyed();  
        }catch(MIDletStateChangeException e){  
            //  
        }  
    }  
 
}  

模型(Model)

UserDataItem.Java

package com.token.model;  
 
import com.token.util.StringDealMethod;  
 
public class UserDataItem {  
    private int id;  
    public String name = null;  
    public String passwd = null;  
 
    public UserDataItem(String name,String passwd)  
    {  
        this.name = name;  
        this.passwd = passwd;     
    }  
      
    public UserDataItem(int id,byte[] data){  
        this.id=id;  
        String temp=new String(data);  
        String temp_sub[] = StringDealMethod.split(temp, ",");  
        this.name = temp_sub[0];  
        this.passwd = temp_sub[1];  
    }  
      
    public int getId(){  
        return id;  
    }  
      
    public void setId(int id){  
        this.id=id;  
    }  
      
    public String getName(){  
        return name;  
    }  
      
    public void setName(String name){  
        this.name = name;  
    }  
      
    public String getPasswd(){  
        return passwd;  
    }  
      
    public void setPasswd(String passwd){  
        this.passwd = passwd;  
    }  
      
    public byte[] getBytes(){  
        String temp=null;  
          
        if(name==null||passwd==null){  
            return null;  
        }else{  
            temp=name+","+passwd;  
        }  
          
        return temp.getBytes();  
    }  
}  

控制(control)

UIController.Java

package com.token.util;  
 
import Java.io.IOException;  
 
import Javax.microedition.lcdui.*;  
 
import com.token.midlet.MainMidlet;  
import com.token.model.*;  
import com.token.vIEw.*;  
//import com.token.vIEw.components.Color;  
 
public class UIController {  
 
    private MainMidlet midlet;  
      
    private TokenDataRecord tokenRecord;  
      
    private WelcomeScreen welcomeScreen;  
    private UserRegist reg;   
    private ActiveScreen activeScreen;  
    private MainScreen mainScreen;  
    private GenPasswd gen;  
    private CheckScreen check;  
    private ViewToken vIEwToken;  
    private UserManage manage;  
    private ShowHelp help;  
    private UserAuth auth;  
    private PopUpTextBox textBox;  
      
    int id = 1;  
      
    public UIController(MainMidlet midlet)  
    {  
        this.midlet = midlet;  
          
        tokenRecord = new TokenDataRecord();  
    }  
      
    public void init() throws IOException{  
          
        try {  
            SplashScreen splashScreen = new SplashScreen();  
            setCurrent(splashScreen);  
            Thread.sleep(1000);  
              
            Configure.configureColor();  
            initObject();     
              
            //tokenRecord.db_deleteAllRecord();  
            if(tokenRecord.db_getRecord(1)==null)  
            {  
                //System.out.println("add");  
                ChaosMethods method = new ChaosMethods();  
                TokenDataItem tokenItem = new TokenDataItem(1,(method.ChaosInitCode()+",false").getBytes());  
                id=tokenRecord.db_addRecord(tokenItem);  
            }  
              
            //System.out.println(id);  
            TokenDataItem tokenItem1 = tokenRecord.db_getRecord(id);  
            //System.out.println(tokenItem1.token+","+tokenItem1.isActive);  
              
            if(tokenItem1.getStatus().equals("false"))  
            {  
                this.handleEvent(UIController.EventID.EVENT_NEXT_WELCOME_SCREEN,null);  
            }else 
            {  
                String flag = "0";  
                Object [] args = {flag,""};  
                this.handleEvent(UIController.EventID.EVENT_MAIN_SCREEN,args);  
            }  
        } catch (InterruptedException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
        }  
          
    }  
      
    private void initObject()  
    {  
        welcomeScreen = new WelcomeScreen(this);  
        reg= new UserRegist(this);  
        activeScreen = new ActiveScreen(this);  
        ...  
        textBox = new PopUpTextBox(this,"輸入文本","", 1000, TextFIEld.ANY);  
    }  
      
    //getMethod  
    public void setCurrent(Displayable disp){  
        midlet.setCurrent(disp);  
    }  
    public void setCurrent(Alert alert, Displayable disp){  
        midlet.setCurrent(alert, disp);  
    }  
      
    //定義事件ID內部類  
    public static class EventID{  
        private EventID(){  
        }  
          
        public static final byte EVENT_EXIT = 0;//退出  
        public static final byte EVENT_NEXT_WELCOME_SCREEN = 1;//歡迎界面  
        public static final byte EVENT_NEXT_USER_REGIST_SCREEN = 2;//用戶注冊  
        public static final byte EVENT_USER_REGIST_EDIT = 3;//用戶注冊編輯  
        public static final byte EVENT_USER_REGIST_EDIT_BACK = 4;//用戶注冊編輯返回  
        public static final byte EVENT_NEXT_ACTIVE_SCREEN = 5;  
       //...  
    }  
      
    //事件處理  
    public void handleEvent( int eventID, Object[] args)  
    {  
        switch (eventID)  
        {     
            case EventID.EVENT_EXIT:  
            {  
                midlet.exit(false);  
                break;  
            }  
            case EventID.EVENT_NEXT_WELCOME_SCREEN:  
            {  
                    welcomeScreen.show();  
                midlet.setCurrent(welcomeScreen);  
                break;  
            }  
            case EventID.EVENT_NEXT_USER_REGIST_SCREEN:  
            case EventID.EVENT_USER_REGIST_EDIT_BACK:  
            {  
                reg.show(args);  
                Thread thread = new Thread(reg);  
                thread.start();  
                midlet.setCurrent(reg);  
                break;  
            }  
            case EventID.EVENT_USER_REGIST_EDIT:  
            {  
                textBox.init(args);  
                midlet.setCurrent(textBox);  
                break;  
            }  
            case EventID.EVENT_NEXT_ACTIVE_SCREEN:  
            {  
                activeScreen.show(args);  
                Thread thread = new Thread(activeScreen);  
                thread.start();  
                midlet.setCurrent(activeScreen);  
                break;  
            }  
            //...  
            default:  
                break;  
        }  
    }  
}