代理模式的UML类图与实现源码

以下是一个代理模式的UML图：

源码：Image接口

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public interface Image { void show();}

?BigImage类

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public class BigImage implements Image {public BigImage(){try {//系统延时3秒用来模拟调用大图片时有系统延时Thread.sleep(3000);System.out.println("Image Successfully loaded.");} catch (InterruptedException e) {// TODO: handle exceptione.printStackTrace();}}public void show() {System.out.println("Draw Real Image");}}

?ImageProxy类

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public class ImageProxy implements Image {private Image image;public ImageProxy(Image image){this.image=image;}public void show() {if(image==null){image=new BigImage();}image.show();}}

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BigImageTest类(客户端)

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public class BigImageTest {public static void main(String[] args) {System.out.println("使用代理");               //null,确保每次调用show方法需要示例化BigImageImage image=new ImageProxy(null);System.out.println("开始显示图片");image.show();System.out.println("***************************************");System.out.println("没使用代理");Image image2=new BigImage();image2.show();}}

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