Talk:Proxy pattern

proxy

Isn't the Firewall proxy the same as Protection proxy? no91.186.200.21 12:51, 11 November 2007 (UTC)

ProxyImage code is overengineered

import java.util.*;
 
class RealImage {
    private String filename;
    private Image image;
 
    public RealImage(String filename) { this.filename = filename; }
    public void displayImage() {
        if (image == null) {
            loadImageFromDisk(); // load only on demand
        }
        // Display image code here.
    }

    private void loadImageFromDisk() {
        // Potentially expensive operation
        // ...
        // initializes image object
        System.out.println("Loading   "+filename);
    }
}
 
class ProxyExample {
    public static void main(String[] args) {
        RealImage image1 = new RealImage("HiRes_10MB_Photo1") );
        RealImage image2 = new RealImage("HiRes_10MB_Photo2") );

        image1.displayImage(); // loading necessary
        image2.displayImage(); // loading necessary
        image2.displayImage(); // no loading necessary; already done
        // the third image will never be loaded - time saved!
    }
}

The proxy pattern isn't needed at all!!! Diegofd (talk) 16:11, 16 May 2008 (UTC)

Copyright violation?

This edit seems a copyright violation from http://userpages.umbc.edu/~tarr/dp/lectures/Proxy.pdf (4/4/2004; 69 KB) the date of pdf is set before the edit Lusum (talk) 11:23, 11 June 2008 (UTC)

Mistake in example?

Current version:

class ProxyImage implements Image {
    private String filename;
    private Image image;
 
    public ProxyImage(String filename) { this.filename = filename; }
    public void displayImage() {
        if (image == null) {
            image = new RealImage(filename); // load only on demand
        }
        image.displayImage();
    }
}

Can interfaces such as "Image" be used as types?

Would this (still) be correct?

class ProxyImage implements Image {
    private String filename;
    private RealImage image;
 
    public ProxyImage(String filename) { this.filename = filename; }
    public void displayImage() {
        if (image == null) {
            image = new RealImage(filename); // load only on demand
        }
        image.displayImage();
    }
}

Notice the difference between private Image image; and private RealImage image;.

Thanks, Abdull under IP --134.91.225.10 (talk) 16:24, 18 September 2008 (UTC)