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技術社區[雲棲]
【設計模式】【代理模式，大圖片加載】
/**
* Description:
* <br/>網站: <a href="https://www.crazyit.org">瘋狂Java聯盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public interface Image
{
void show();
}
/**
* Description:
* <br/>網站: <a href="https://www.crazyit.org">瘋狂Java聯盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
//使用該BigImage模擬一個很大圖片
public class BigImage implements Image
{
public BigImage()
{
try
{
//程序暫停3s模式模擬係統開銷
Thread.sleep(3000);
System.out.println("圖片裝載成功...");
}
catch (InterruptedException ex)
{
ex.printStackTrace();
}
}
//實現Image裏的show()方法
public void show()
{
System.out.println("繪製實際的大圖片");
}
}
/**
* Description:
* <br/>網站: <a href="https://www.crazyit.org">瘋狂Java聯盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public class ImageProxy implements Image
{
//組合一個image實例，作為被代理的對象
private Image image;
//使用抽象實體來初始化代理對象
public ImageProxy(Image image)
{
this.image = image;
}
/**
* 重寫Image接口的show()方法
* 該方法用於控製對被代理對象的訪問，
* 並根據需要負責創建和刪除被代理對象
*/
public void show()
{
//隻有當真正需要調用image的show方法時才創建被代理對象
if (image == null)
{
image = new BigImage();
}
image.show();
}
}
/**
* Description:
* <br/>網站: <a href="https://www.crazyit.org">瘋狂Java聯盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public class BigImageTest
{
public static void main(String[] args)
{
long start = System.currentTimeMillis();
//程序返回一個Image對象，該對象隻是BigImage的代理對象
Image image = new ImageProxy(null);
System.out.println("係統得到Image對象的時間開銷:" +
(System.currentTimeMillis() - start));
//隻有當實際調用image代理的show()方法時，程序才會真正創建被代理對象。
image.show();
}
}
最後更新：2017-04-04 07:03:38