Proxy pattern

Proxy는 대리인이라는 뜻으로, 뭔가를 대신해서 처리하는 것

Proxy Class를 통해서 대신 전달하는 형태로 설계되며, 실제 Client는 Proxy로 부터 결과를 받는다.

Cache의 기능으로도 활용이 가능하다.

SOLID중에서 개방폐쇄 원칙(OCP)과 의존 역전 원칙(DIP)를 따른다.

 

 

package com.company.design.proxy;

public interface IBrowser {
    HTML show();
}

package com.company.design.proxy;

public class HTML {

    private String url;

    public HTML(String url){
        this.url = url;
    }
}

package com.company.design.proxy;

public class Browser implements IBrowser{

    private String url;

    public Browser(String url){
        this.url = url;
    }

    @Override
    public HTML show() {
        System.out.println("browser loading html from : " + url);
        return new HTML(url);
    }
}

package com.company.design.proxy;

public class BrowserProxy implements IBrowser{

    private String url;
    private HTML html;

    public BrowserProxy(String url){
        this.url = url;
    }

    @Override
    public HTML show() {

        if (html == null){
            this.html = new HTML(url);
            System.out.println("BrowserProxy loading html from : " + url);
        }
        System.out.println("BrowserProxy use cache html : " + url);
        return html;
    }
}

package com.company.design.aop;

import com.company.design.proxy.HTML;
import com.company.design.proxy.IBrowser;

public class AopBrowser implements IBrowser {

    private String url;
    private HTML html;
    private Runnable before;
    private Runnable after;

    public AopBrowser(String url, Runnable before, Runnable after){
        this.url = url;
        this.before = before;
        this.after = after;
    }

    @Override
    public HTML show() {
        before.run();
        if (html == null){
            this.html = new HTML(url);
            System.out.println("AopBrowser html loading from : " + url);
            try {
                Thread.sleep(1500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        after.run();
        System.out.println("AopBrowser html cache : " + url);
        return null;
    }
}

package com.company.design;

import com.company.design.adapter.*;
import com.company.design.aop.AopBrowser;
import com.company.design.proxy.Browser;
import com.company.design.proxy.BrowserProxy;
import com.company.design.proxy.IBrowser;
import com.company.design.singleton.Aclazz;
import com.company.design.singleton.Bclazz;
import com.company.design.singleton.SocketClient;

import java.util.concurrent.atomic.AtomicLong;

public class Main {


    public static void main(String[] args) {

        IBrowser browser = new BrowserProxy("www.naver.com");
        browser.show();
        browser.show();
        browser.show();
        browser.show();

        AtomicLong start = new AtomicLong();
        AtomicLong end = new AtomicLong();

        IBrowser aopBrowser = new AopBrowser("www.naver.com",
                () -> {
                    System.out.println("before");
                    start.set(System.currentTimeMillis());
                },
                () -> {
                    long now = System.currentTimeMillis();
                    end.set(now - start.get());
                }
                );

        aopBrowser.show();
        System.out.println("loading time : " + end.get());

        aopBrowser.show();
        System.out.println("loading time : " + end.get());
    }

}