java/w10/AbstractCrawlerStrategy.java

package strategy;

import model.Paper;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public abstract class AbstractCrawlerStrategy implements CrawlerStrategy {
    protected Random random = new Random();
    
    @Override
    public List<Paper> crawl(String url, int count) throws Exception {
        List<Paper> papers = new ArrayList<>();
        papers.addAll(fetchPapers(url, count));
        return papers;
    }
    
    protected abstract List<Paper> fetchPapers(String url, int count) throws Exception;
    
    protected void addDelay(int minMs, int maxMs) {
        try {
            int delay = minMs + random.nextInt(maxMs - minMs + 1);
            Thread.sleep(delay);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }
}