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构建基于MVC+Observer模式的、艺术性的移动开发框架（KJAVA版）(二)

news 来源：原创 2024/9/22 17:22:05

构建基于MVC+Observer模式的、艺术性的移动开发框架（KJAVA版）(二)

Author: 孙东风

Date:03/12/2007

在上一讲中,我们利用MVC+Observer模式设计了移动开发框架。那么,这一节里我们会以一个"媒体播放"为具体实例来实现这个框架。

首先,可以利用UML建模工具进行如下类的设计:

这个类图对应上节我们所讲解的框架设计。

以下是根据这个类图进行的具体coding:

import javax.microedition.lcdui.Graphics;

public class Controls {

boolean isActive = false;

public Controls()
{

}

public void draw(Graphics g)
{

}
}

/**
*
* @author jerry.sun
* @date 2007-11-29 下午12:43:09
*/

public class MediaPlayerControl implements MediaPlayerObserver{

public MediaPlayerView m_view;
public MediaPlayerModel m_model;

public MediaPlayerControl()
{
m_view = new MediaPlayerView();
m_model = new MediaPlayerModel(this);
}

public void SreenUpDate()
{
m_view.CanvasStatusChange();
}
}

/**
*
* @author jerry.sun
* @date 2007-11-29 下午12:40:31
*/

public class MediaPlayerModel implements Runnable{

public MediaPlayerControl m_control;
Queue tempEventsQueue;

public MediaPlayerModel(MediaPlayerControl control)
{
m_control = control;
tempEventsQueue = MediaPlayerView.eventsQueue;
}

public void parseEventsQueue()
{
Object event = tempEventsQueue.get();
int eventID = 0; //event.id;

switch(eventID)
{
case 0:
break;
case 1:
break;
case 2:
break;
default:
break;
}

m_control.SreenUpDate();
}

public void run() {
// TODO Auto-generated method stub
parseEventsQueue();
}

}

/**
*
* @author jerry.sun
* @date 2007-11-29 下午12:43:34
*/

public interface MediaPlayerObserver {

public void SreenUpDate();
}

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Graphics;

/**
*
* @author jerry.sun
* @date 2007-11-29 下午12:43:43
*/

public class MediaPlayerView extends Canvas implements Runnable{

static Queue controlsQueue;

static Queue eventsQueue;

public MediaPlayerView()
{
controlsQueue = new Queue();

if(!initControlsQueue())
System.out.println("Maybe the ControlsQueue is full!");
}

public boolean initControlsQueue()
{
return controlsQueue.put(new Controls())
&&controlsQueue.put(new Controls());
//continue...
}

protected void CanvasStatusChange()
{

}

protected void paint(Graphics g) {
// TODO Auto-generated method stub

for(int i = 0;i < controlsQueue.length();i++)
{
Controls tempCon = (Controls)controlsQueue.get();
if(tempCon != null&& tempCon.isActive)
{
tempCon.draw(g);
}else
{
System.out.println("The "+tempCon+" is not activity!");
}
}

}

public void run() {
// TODO Auto-generated method stub

}
}

/**
*
* @author jerry.sun
* @date 2007-11-29 下午12:43:57
*/

public class Queue {
/** 队列的最大长度 */
public static final int MAX_SIZE = 32;
private Object queueArr[] = null;

private int queueHeadId = 0;
private int queueTailId = 0;
private int queueLength = 0;

/** 初始化 */
private void init() {
queueHeadId = 0;
queueTailId = 0;
queueArr = new Object[MAX_SIZE];
for ( int ii = 0; ii < queueArr.length; ii ++) {
queueArr[ii] = null;
}
}

/** 取下一个节点的下标 */
private static int nextID(int id) {
return ( id + 1 ) % MAX_SIZE;
}

/** 取前一个节点的下标 */
private static int preId(int id) {
return ( id + MAX_SIZE - 1) % MAX_SIZE;
}

/** 添加一个 obj 到队列,如果队列满，返回false,正常返回true */
public synchronized boolean put(Object obj) {
if ( isFull() )
return false;
queueArr[queueTailId] = obj;
queueTailId = nextID(queueTailId);
queueLength ++;
return true;
}

/**
* 队列中取出一个 obj,如果队列空，返回 null
* 取出的obj弹出队列
*/
public synchronized Object get() {
if ( isEmpty())
return null;

Object obj = queueArr[queueHeadId];
queueHeadId = nextID(queueHeadId);
queueLength --;
return obj;
}

/**
* 队列中取出一个 obj,如果队列空，返回 null
* 取出的obj不弹出队列
*/
public synchronized Object getWithoutPop()
{
if ( isEmpty())
return null;

Object obj = queueArr[queueHeadId];
return obj;
}

/**
* 当前队列中Obj个数
*/
public int length() {
return queueLength;
}

/**
* 是否队列已经满了
*/
public boolean isFull() {
return queueLength == queueArr.length;
}

/**
* 是否队列是空队列
*/
public boolean isEmpty() {
return queueLength == 0;
}

/** Creates a new instance of Queue */
public Queue() {
init();
}

}