Java的代理模式例子

(1).  創建一個接口, 要代理的類和 代理類都將繼承它

package stone;
public interface Image {
    public void show();
}

 

(2). 創建要被代理的類:

package stone;
public class BigImage implements Image {
    public BigImage() {
        try {
            Thread.sleep(3000);                      // 模擬大圖片要用長時間來加載
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("loading big image ");
    }
    public void show() {
        System.out.println("show image");
    }
}

 

(3). 創建代理類

package stone;
public class TestProxy {
    public static void main(String[] args) {
        long start= System.currentTimeMillis();
        Image image= new ImageProxy(null);
        System.out.println("Load time:"+String.valueOf(System.currentTimeMillis()-start));
        image.show();
        System.out.println("Show time:"+String.valueOf(System.currentTimeMillis()-start));
    }
}

 

(4). 運行測試類,測試代理模式:

package stone;
public class TestProxy {
    public static void main(String[] args) {
        long start= System.currentTimeMillis();
        Image image= new ImageProxy(null);
        System.out.println("Load time:"+String.valueOf(System.currentTimeMillis()-start));
        image.show();
        System.out.println("Show time:"+String.valueOf(System.currentTimeMillis()-start));
    }
}

 

測試結果:

Load time:0
loading big image
show image
Show time:3000